DIGEST No. 39, SEPT EMBER, 1964

PRINTED BY HE DGES A BELL. LTO .. MARYBOROU GH, VIC •

AUSTRALIA AVIATIO N SAF E TY DIG E ST

No. 39 SEPTEMBER, 1964

Prepared in the Air Safety Investigation Branch, Depa rtment of Civil Avia tion, Commonwealth of A ustrali a

Contents

L anding on Wet Runways

Is Your Lighter Safe ? 3

Another Fata l Missed Approach - 4

Take Your Wheels with You ! 7 We are fortunate that our Australian climate has aquapla ning becomes possible for varying tyre pres­ False Positi on R eports - Twice ! 8 made our airports almost immune from the hazards sures and the following table sets out the tyre pres­ of ice and snow which aircraft so frequently sures a nd the approximate critical aquaplaning Not Clear - 9 encounter on northern hemisphere runways during speeds for the aircraft types used in domestic opera­ winter months. Unfortunately however, this im­ tions in Australia. It will be noticed that the critical Lightning and Aircraft 10 munity does not extend to the conditions in which speeds a re greater in the case of aircraft with high aquapla ning ca n occur. The dangers common to pressure tyres. It is also evident that high landing The Missing Link - 17 wet ruriway o perations and those on ice or snow speeds tend to promote aquaplaning and it is there­ are loss of bra king effect and reduced controllability fore particularly important to a void excessive touch­ Confused in a Coma nche 18 of the aircraft. If a nything, aquaplaning is a greater down speeds when landing on wet runways. The menace than ice and snow in this regard. Sus­ table also illustrates that aquaplaning can occur F ailure Forestalled 20 ceptibility to aquaplaning has been accentuated in during the ground run that follows a n abandoned recent yea rs by th~ characteristics of modern aircraft take-off. O verseas Accidents in Brief 21 types. Aeroplane Type Tyre Pressure Approx. When an aircraft is moving on a wet runway, ps.i. critical An Augmentor Tube H azard 23 the water lying on the surface acts as a lubricant (Main Wheels) aquaplaning speed-(knots) Li ght aircraft line the tarmac at to reduce the friction between the runway surface Perth at the start of a 500 mile Pitot Static Icing - 24 and the aircraft tyres. It also produces a build-up Lockheed Electra ...... 130 103 ra ll y held in Western Australia recently. of pressure beneath the tyres, so decreasing the load Douglas DC6B ...... 106 93 Out of Fuel ! 27 transmitted by the tyres to the surface of the run­ Viscount 800 Series ...... 101 91 - Photograph by courtesy A ir BP way and reducing the friction available for brak­ Viscount 700 Series ... . . 87 84 My Thoughts fo r a Safe Flight 28 ing. As the speed increases, the pressure build-up Convair 440 ...... 72 76 under the tyres also increases. If there is a suf­ Douglas DC4 ...... 72 76 ficient depth of water on the runway surface, the Fokker Friendship ... . 75 78 stage will be reached where the load on the wheels Douglas DC3 ...... 48 63 is equalled by the water pressure being developed Bristol Freighter ...... 60 70 Except for that material which is indicated to be extracted / re m or based 011 another publication, in which case the authority of the originator should be sought, the malerial contained herein may be freely reproduced in p11blica1ions intended prim arily under the tyres and total aquaplaning occurs. The DeHavilland Dove ...... 46 61 for circulation in the A vimi on Industry. A II other p11blicatio 11 , whether by the printed word, radio, or television, m ust hm•e graph in Fig. l shows the speeds at which total Piaggio 166 ...... 48 63 the prior approval of the Department of Civil A viatio11. SEPTEMBER, 1964 tribute to the establislunent of aquaplaning con­ 20 0 same speed as the aircraft is moving, and so the about 70 to 80 per cent. of the maximum brake ditions. A fi rm touch-down should therefore be I/ ~lip ratio is zero. Conversely, when maximum brak­ force coefficient theoretically available at the ~ 18 0 made when landing on a wet runway as this will z: ing stops the wheels rotating altogether, the slip optimum slip ratio, they are far more effective than Literally drive the wheels through the film of water d160 / ratio is 100 per cent. The graph shows that the braking which is directly controlled by the pilot. en v to make positive contact with the runway surface ~ maximum brake force coefficient is obtained at a Because of this, it is important that these anti-skid ~14 0 itself. 0.. / slip ratio of between 10 and 20 per cent. In modern devices be used for landings on wet runways to ~12'" - It is important to realize that even when there aircraft, anti-skid devices are installed to take ad­ obtain the highest brake force coefficient possible ...... is no actual aquaplaning, the braking fo rce avail­ vantage of this fact by ensuring that the wheels in the prevailing conditions. g; 1010 v able to an aircraft is substantially reduced by the will not lock despite the application of maximum en As has already been mentioned, the risk of ~8 0 v lubricating effect of the water on a wet runway. braking by the pilot. Although the most efficient cc aquaplaning is not necessarily confined to landings 0.. T his braking fo rce is technically known as the anti skid devices in use are only able to achieve ..... 60 v in the wet. It could occur to an aircraft which has ~ brake force coefficient, and the graph in F ig. 2 to abandon a take-off in heavy rain. Remote as > .,v shows the variation in the maximum obtainable I- 40 this possibility may seem, it would be unwise to / brake force coeffi cient over a range of speeds for 1007. TYPICAL VAR IAT I ON / completely overlook the potential consequences of 20 both wet and dry runways. It will be noticed that OF BRAKE FORCE ~ w w 100 1ro 140 WITH SLIP aquaplaning during such an operation. AqUAPLANING SPEED IN KNOTS the brake force coefficients are high on a dry run­ way and decrease as the speed rises. On wet sur­ POSSIBLE AQUA PLANING SPEEDS FOR TYRES In considering the problem of aquaplaning faces however, the brake force coeffi cients are not generally, it is worth remembering that once rain FIG. 1 has ceased to fall in quantity, it is usually only a matter of minutes before a runway drains sufficiently to preclude the possibility of aquaplaning. There Tn addition to the speed of the aircraft on the run­ 0 20 40 60 80 100 are probably times when it is worth delaying a way and the pressure of its tyres, the other impor­ SLI P RAT IO PERCENT take-off or landing for a short time to a void a potentiall y dangerous situation. tant factor affecting aquaplaning is the depth of ...... FIG. 3 water lying on the runway. A depth of only one­ C....3t­ ~:z: 1--~-+-~~t--~-t-~...... ,..-~-t-~---t ~---i C> ...... eighth of an inch of water is usually sufficient to in­ ...... C....3 duce aquaplaning and smooth or worn tyres can ...... ~ ::!:; aquaplane in as little as one-tenth of an inch. Con­

2 AVIATION SAFETY DIGEST S EPTEMBER , 1964 3 ' Fatal Missed Approach

could have contributed to the ac­ hours, and this is assumed to be a IL became clear during the in­ When the pilot of a Cessna 172 attempted to carry out a missed approach at an agricultural cident. It was determined that the measure of his actual experience. vestigation that the weather condi­ airstrip near Lithgow, N.S.W., the aircraft stalled and crashed. The pilot sustained fatal injuries ai rcraft was loaded within its speci­ It was learned. however, that he had tions which prevailed at the time and the passenger was seriously injured. fied limits. At the same time fostered the impression at Banks­ were closely related to the cause of however, it was found that three town Airport that he was a Com­ the accident. There was no doubt 14 pound cartons of spark plugs mercial Pilot of some 3000 hours concerning the accuracy of the fore­ had been carried in the luggage experience. In fact, on one occasion cast given to the pilot and this, to­ The aircraft had been hired by lention of returning directly to and high ground beyond the end of locker of the aircraft without having he had even stated this in writing gether with actual observations of the pilot for the purpose of making Bankstown but, when the main the strip and had started to raise been secured against movement and to the operators of a flying school the weather by witnesses, showed a trip from Baokstown to Orange, western railway li ne was intercepted the flaps gradually when the stall that they had been hurled from the at Bankstown. The owners of the that the aircraft had indeed reached N.S.W., in company with a business a few minutes later, he elected to warning began to blow continuously. locker into the cabin when the air­ aircraft in which the accident oc­ a point where it was impossible to associate. Before departing, the foll ow the railway. Several miles Even so, while still turning to the craft crashed, and one was found to curred had hired it to the pilot on continue VFR. By this time, how­ pilot called at the Briefing Office at further on, an agricultural airstrip left, the aircraft climbed very slug­ have burst open. It is not known the strength of this claim, being ever, the low cloud and rain had in­ Bankstown Airport to obtain a was sighted and the pi lot decided to gishly over the rising ground and the whether the head injuries sustained satisfied that he would be quite creased to the stage where a safe weather forecast. Discussing the attempt a landing. highway towards the crest of the by the pilot were the result of his capable of safely assessing the mar­ return flight to Bankstown was also weather likely to be encountered li ill. As it approached the power having been struck by the cartons. ginal weather that the flight was ex­ very doubtful and so the pilot was along the route, the Briefing Officer The agricultural strip concerned is line and some trees near the top of In any case, the pilot did not pected to encounter. Had they virtually committed to a precaution­ pointed out that already that day, situated very close to the Great the rise at a height of only about properly restrain the load as is re­ known the pilot's actual recorded ary landing. Although he did not two other aircraft had abandoned Western Highway on mountainous thirty feet, it stalled. The port quired by Air Navigation Order experience, it is very probable that indicate his intentions to the passen­ attempts to fly over the ranges be­ terrain 4000 feet above sea level. It wi ng struck the ground and the air­ 20.16.2.1.2. and thus did not comply they would not have authorized the ger when the aircraft intercepted cause of low cloud, and he strongly is 2000 feet long and has an upward craft crashed on its back and slid with Air Navigation Regulations flight. The circumstances of this the railway, it seems that the pilot advised the pilot not to attempt the gradient of approximately three de­ inverted for several yards before 227(6) and 227(7). accident underline the necessity for turned and followed it simply be­ flight. Nevertheless, the pilot stated gress ( l :20) towards a tree-covered colliding with logs lying on the The pilot held a Private Pilot flying schools and other aircraft cause he had no alternative in the that he would "give it a go". He hill which rises almost 100 ft. above ground at the base of the trees. The Licence endorsed for Cessna 172 air­ operators to examine the log books existing conditions. The agricultur­ declined to submit a flight plan or the upper end of the strip. Looking impact fl ung the tail high into the craft. His recorded flying exper­ of pilots before authorizing "in al airstrip was evidently the fi rst nominate a SARTIME and the air­ up the strip from the approach end, air against the power line and it slid ience was slightly less than 260 command" flights. likely landing place the pilot saw craft took off for Orange at 1320 the terrain on the left falls away several feet along the wires before amid the rugged mountain terrain, hours. slightly then slopes gently up to­ crashing back to the ground. The and he grasped at the opportunity wards a lightly timbered hill of aircraft finally came to rest upside it offered. The flight was uneventful until roughly the same height as the upper down 45 feet from the point of first N The fact that the aircraft overshot the aircraft began to approach the end of the strip. The highway and impact and approximately 600 feet during the approach to land on the higher sections of the Great Divid­ a power line cross thi s hill before from the airstrip. strip is not at all surprising when ing Range some minutes after turn ing to pass immediately above the circumstances are considered. The accident was witnessed by the passing abeam of Katoomba. Cloud the end of the strip. To the right In the fi rst place, the pilot's total occupants of two cars that were cD then forced the pilot to descend of the strip, the ground also falls OsuPER experience was limited, and was travelling on the section of highway DUMP un til the aircraft was flying low over away slightly at first but then rises spread over a period of some twelve adjacent to the scene of the crash. the mountainous terrain and the steeply into a heavily timbered spur. years. During the year preceding the The witnesses hurried to the scene passenger suggested that they should accident he had flown only 22 hours. and were responsible for extinguish­ turn back. By making several Because the cloud base in the Secondly, his experience on the air­ ing a small fi re which had broken northerly diversions from his in­ vicinity of the strip was no more craft type amounted to only 17 out in the engine compartment of tended track however, the pilot was than 300 feet, the pilot had to com­ hours. It has been found that in­ the aircraft when the fuel fil ter r able to continue the flight in a mence his approach to land from a GRADI ENT experienced pilots often misjudge shattered and splashed fuel on to general north-westerly direction for left base leg made at low level. DOWN an approach when they enter a cir­ the hot exhaust system. They also another fifteen minutes or so until Landing flap was used but the air­ cuit area at an unfamiliar height, arranged for an ambulance to be the aircraft was approximately due craft overshot, and after traversing and so the third factor against the called, assisted in extricating the oc­ west of Lithgow. Further VFR half the length of the strip was still chances of a successful precaution­ cupants from the wreckage, and ob­ flight westwards then became im­ several feet above the ground. At .. ary landing was the necessity for tained the services of a doctor. possible and the pilot was forced to this point the pilot abandoned the making the circuit at a low alti­ turn the aircraft on to a reciprocal landing and opened the throttle to A detailed examination of the tude. Finally there was the airstrip heading. He maintained this in make another circuit. He com­ aircraft wreckage was made but itself. Such characteristics as its misty light rain and poor visibility menced a turn to the left almost there was no evidence to suggest slope and the proximity of obstruc­ ROAD fo r several minutes with the in- immediately to avoid the power li ne that any pre-crash defect or failure tions might well have been con-

4 A VI A TIO N S AF ET Y D I GEST S E PTEM BER, 1 964 s fusing to the pilot, particularly in wo uld have had to climb 75 feet the smallest of margins but it could the state of mental stress to which before reaching the hill to clear the not gain the additional 15 feet he would have undoubtedly been obstructions. Calculations indicate necessary to clear the trees and subjected at the time. that at an altitude of 4000 feet it power line a little further up the As a result of the overshoot, the is doubtful if a Cessna 172 could hill. The pilot realized that the air­ aircraft was still nearly ten feet achieve the gradient of climb craft was going to collide with the above the ground when it was ap­ this would have demanded, even at trees and he attempted to tighten proximately half way up the airstrip. the optimum airspeed and flap the turn to the left to avoid them, Even so, it is very probable that settings. On this occasion however, but the airspeed of the aircraft was so dangerously low that the increase the aircraft could have been brought the performance of the aircraft was in the rate of turn induced a stall to a standstill in the remaining severely handicapped by the circum­ and the aircraft crashed. length if the pilot had persisted with stances in which it had been placed. the landing. Even if this could not The fact that the stall warning had lt is apparent that the acciden t have been achieved, the conse­ started blowing almost as soon as stemmed from the pilot's attempt quences of over-running the end of the missed approach was com­ to carry out a missed approach pro­ the strip would have been fa r less menced, shows that the airspeed was cedure which was beyond the per­ Take Your Wheels serious than those of attempting an­ very low. As well as this, the flaps formance of hi s aircraft. The weath­ other circuit. An experienced pilot bad been lowered to at least 30 er conditions existing at the time, with YOU! would probably have appreciated and probably 40 degrees, and the together with the lack of experience this fact, and made the best of the resulting drag would have seriously displayed by the pilot firstly in per­ landing in the space that remained. hindered the aircraft's performance. sisting with the flight into adverse The aircraft, once it had turned, Once the pilot had opened the weather, and then in misjudging his would also have had a tail wind throttle and committed himself to approach to land, were contributing acting on it and although light, this a missed approach, his only possible factors. would have had some effect in de­ "Where can I locate my wheel?" So wrote the split pin. To make his aircraft more comfortable on course was to commence a turn to creasing the gradient of climb. Last­ It was fortunate in the circum­ pilot of a light aeroplane in reply to an enquiry from the ground, this pilot had previously replaced the the left. It was obviously impossible ly, the effect of the turn itself would stances that the site of the accident this Department asking if a wheel found on a South solid-tyred wheel with a pneumatic one, but it was for the aircraft to clear the hill have detracted still further from the was so close to a busy highway Australian country aerodrome had fallen from his his practice to carry the original tyre and fork directly beyond the end of the air­ climb performance of the aircraft where assistance was readily avail­ aircraft. Incredible as this story may sound, it is assembly as a spare. On this occasion, the pneumatic strip and yet higher terrain lay to at its low airspeed. able, especially as the aircraft was true! tail wheel had been punctured after landing so it the right. The only flight path thus endangered by fire. Although there was removed by raising the tail of the aircraft, un­ lay towards a bill which, although The cumulative effect of these was no legal requirement for this When the Senior Groundsman of the aerodrome doing the castle nut and pulling out the pivot bolt. much lower than the others, was still factors thus reduced the perform­ pilot to have availed himself of the was making his regular inspection of the movement The spare assembly was then substituted and the nut as high as the upper end of the strip ance to the point where it was utter­ Department's Search and Rescue area, be discovered what appeared to be a tail wheel replaced and tightened but, because the split pin with trees and a power line located ly impossible for the aircraft to out­ facilities, the frequent failure of and fork from an Auster aircraft. It was learned had been lost in the grass, the nut was left unlocked. m;ar its crest. climb the obstructions on the rising some pilots to make use of this that only one light aeroplane had landed at the The pilot's fi rst inkling that anything was amiss ground ahead. It missed the tops self protection service continues to aerodrome during the preceding two days and so This meant that from the com­ .:as when he land ed back at his home after a flight mencement of its turn, the aircraft · of the trees lining the highway by surprise us. the Department immediately wrote to the owner/ pilot to see if he could shed any light on the mystery. from the aerodrome concerned. The nut apparently The pilot replied, confessing his embarrassment at worked loose while the aircraft was taxying on de­ the situation but at the same time admitting his parture and the assembly probably fell off during the ERRATUM relief that the tail wheel had been fo un'd ! His take-off run. No damage was done to the aircraft when it landed as the leaf spring to which the tail In the article " The Bird Problem", published letter went on to explain how the predicament had in the June issue of the Digest, the names of . occurred . wheel assembly had been attached, acted as a tail Dr. Gerard van Tets and Dr. H. J. Frith were skid. incorrectly spelt. Most Auster variants are fitted with a solid As the pilot pointed out in his letter, he has learn­ We apologize for this error. rubber-tyred tail wheel as standard equipment. The ed that nuts will not stay on without being locked. tail wheel is mounted in a swivelling fork which He hopes someone else might benefit from his ex­ castors on a pivot bolt retained by a castle nut and perience!

6 AVIATION SAFE TY DIGEST SEPTEMBER, 1 964 7 Lransmitted the circuit area report on the basis that last light. Nevertheless the flight appeared to pro­ he had identified himself in the general area of ceed normally, and punctually on the E TA Kal­ the co-ordinates given to him as the site of his goorlie received a report "Circuit area --, finished destination. Some forty minutes later, when he fo r the day, Goodnight". had still not located the actual camp site, he had F ifteen minutes later, a trunk line call was received tried to call Kalgoorlie but his transmission was in Kalgoorl ie from the Postmaster of the township not heard, presumably because of prevailing atmos­ concerned, advising that an aircraft was circling pheric condilions. Still confident that he could the town in darkness and that vehicles were being locate his destination, he had continued searching organised to form a fl are path on the airstri p. Kal­ and making communication checks until hi s calls goorlie then tried unsuccessfully to contact the air­ were finally heard by Perth, but by this time his fuel craft and the Uncertainity Phase was introduced. A was so low that he could neither fly on to the second trunk call a few minutes later reported that correct location nor divert to an alternative aero­ the aircraft had landed safely, and the Uncertainty drome. Although it was established that the flight Phase was then cancelled. had been well planned and the pilot was not to blame for the error in the position of the drilling The pilot's explanation on this occasion was that site, his decision to pass a circuit area report and adverse winds had retarded the aircraft's progress cancel SAR before positively identifying his in­ and that he had given his circuit area call when tended landing point was extremely poor airman­ he had sighted the lights of the town . At this time ship. His subsequent action in remaining in the he was in fact fifteen minutes from his destination. area without radio contact until his fuel was almost Quite obviously the pilot chose to jeopardise the exhausted was similarly inept and was the source safety of hi s aircraft and his three passengers by of much effort and expense on the part of those relying on someone to notice his arrival and arrange responsible for Search and Rescue action. It may a fl are path when, by merely advising Kalgoorlie of not be entirely inappropriate that the date on an amended ETA, he could have ensured that which this flight commenced was 1st April ! all concerned were alerted to the emergency and that all possible facilities would be available to One could be pardoned for concluding that this facil itate a landing in the dark. As it transpired, pilot had learned a valuable lesson and that his it was fortuitous that the Postmaster of this very False Position Reports -Twice! future judgment would be qualified by his humiliat­ small settlement noticed the aircraft and was able ing but educational experience. Regrettably, some to take the correct action to assist the landing. six weeks later this same pilot committed the same error, under different but perhaps even more This pilot was lucky. Although he had chosen to The old adage "once bitten, twice shy", probably applies more truly to the flying fraternity hazardous circumstances. This time he was flying stubbornly disregard the warning of his own earlier than it does to any other group in our community. Indeed, the more prudent ones among us from an oil drilling site to a small township situated experience, he suffered only the indignity of having don't wait to be "bitten" ourselves, but rather try to learn something from the mistakes of others. just under 200 miles to the north-east. The flight the error of his ways pointed out to him in a more departed late in the afternoon and according to direct manner. The history of aviation is studded the flight details passed by radio to Kalgoorlie, the with cases of pilots who have not been nearly so ETA at the destination was only one minute before fortunate. H owever, there are exceptions to every rule, and pilot requesting them to urgently check the map a few pilots not only disregard the warnings con­ co-ordinates for the position of the drilling site tained in accident and incident reports brought as he was still airborne and fuel was running low. to their notice, but even refuse to be cautioned by The owners of the aircraft were contacted for this the results of their own foolhardiness. Having got information and it was then found that the co­ NOT CLE AR away with it once, they evidently believe that fortune ordinates which they had previously given to the will smile on them next time they decide to take pilot were 120 miles south of the true position. By After the crew of a Viscount had completed the "be fore take off' check list and reported "Ready" at Sydney a similar chance. One example of this form of that time the aircraft's remaining endurance was A irport, the tower advised the aircraft to " Line up behind the light aircraft on final" . This was read by both Russian Roulette came to light earlier this year in only thirty minutes and after transmitting the pilots as "Line up - light aircraft on final", which implied to them that after lining up, a take-off clearance Western Australia. Urgency call, "Pan Pan Pan", the pilot advised would follow and the light aircraft would then be cleared to land. that he was heading for a dry salt lake to make a A privately owned light aircraft departed from landing. Twenty minutes later he reported he had As the Viscount entered the runway, the First Officer pointed out a Cessna 172 on final approach, and at Kalgoorlie early one morning for an oil drilling landed the aircraft safely on a track at the edge the same time the tower called "Negative line up . ... ". However, the warnings were too late and the Cessna site located in desolate and almost uninhabited coun­ of the lake. A search aircraft was sent out to was forced to make a missed approach. try more than three hundred miles to the north­ .. establish the actual position of the landing, and east. Atmospheric conditions rendered H /F com­ The incident serves as a reminder that all tower instructions must be clearly understood, and that it is still arrangements were made for a police ground party munication difficult but contact was maintained prudent for pilots to make a visual check to ensure that the runway is in fact clear. We in turn will try to see to carry fuel supplies 160 miles overland to the with Kalgoorlie until the pilot reported "Circuit that our own phraseologies do not contribute to such situations. In this instance, a more appropriate instruc­ site. The aircraft was flown out the next day. Area --, cancel SAR". Two and a half hours tion would probably have been "Cessna on final , - lin e up behind that aircraft". later, Perth heard a weak transmission from the When interviewed, the pilot stated that he had :SEPTEMBER, 1964 9 8 AVIATION SAFETY DIGEST LIGHTNING AND AIRCRAFT

Lightning and its effect on aircraft operations has long· been one of the "mystic" sciences to most members of the aviation industry. Recently however, the Lockheed Aircraft Corporation devoted an enfu·e issue of their Field Service Digest to one of the most informative condensations of this subject that we have yet seen. We aJ'e grateful to the Lockheed Corporation for their permission to reproduce most of this study in our Aviation Safety Digest. Part One A Basis for Discussion The study is divided into three primary parts: Part I - A Basis for Discussion. By A. W. TURNER, Part II - Further Thoughts and Considerations. Lockheed Flight Test Division Engineer Appendix -The Origin of Lightning and its Global Aspects. We have reproduced Part I in this article and it is our intention to include Part II in the next issue. · A little over two hundred years ago on a showery string ended in an insulating silk ribbon.) Struck with The appendix is quite a lengthy study of the theory of lightning and because of spring day in a small French town near Paris, an old this promising appearance, he immediately present­ its size and because we believe its detailed technical content would have a limited soldier named Coiffier neared the climax of a beauti­ ed his knuckle to the key (hung on the string) and - appeal, we do not propose to reproduce it. Nevertheless, to those who are interested fully simple but dangerous experiment suggested by let the reader judge of the exquisite pleasure he must in the whys and wherefores of lightning, we highly recommend a reading of this the American, Benjamin Franklin. With the rumb­ have felt at that moment - the discovery was com­ Appendix. It has been written by the Editor of the Lockheed Service Digest and its ling of thunder in his ears, Coiffier gingerly brought plete. He perceived a very evident electric spark .. . scope is best described in the words of his introduction: a grounded conductor closer to an iron rod, insulated This happened in June, 1752, a month after the elec­ from the earth and reaching upward 40 feet toward tricians in France had verified the same theory, but "This rather large Appendix to the article is felt to be justified because of the black cloud overhead. The old man's heart must before he had heard of anything they had done." the almost universal ig,norance of many persons on the subject of lightning. No have skipped a beat as the first electric spark crack­ offence is meant here, for the writer was, until rece,ntly, well established in this led across the gap. He rushed to bring the village Thus almost simultaneously on both sides of the group. Now, as much as he has learned about lightning is written into this priest to witness this proof that clouds containing Atlantic, the most significant single discovery as to extensive supplement. lightning, as Franklin had predicted, did carry elec­ the nature of lightning (that it is electrical) was tricity and that this electricity could be brought to made. Shortly thereafter, his further efforts led "The story of light.ning encroaches on so many highly specialized areas of earth with conductors. Franklin to conclude that, " ... . the clouds of basic sciences that it is perhaps not surprising that experts on the subject are so thundergusts are most commonly in a negative state few. However, this is not the only problem: scientific facts and theories to Coiffier's employers, scientists D'Alibard, de Lor, of electricity, but sometimes in a positive state - the explain them are being discovered and formulated from day to dcty - the picture and Buffon, soon repeated the experiment themselves latter, I believe is rare." is f orever changing. It is only in the last 20 years or so that the mechanism of and quickly spread the word throughout Europe of lightning came to be understood. And it is only in very rece,nt years that its Franklin's genius and of the success of his plan. The importance of his work in increasing man's significance and its connection with a.n almost closed circuit involving the earth's understanding of his environment is expressed by Meanwhile, in Athercia, Franklin, impatient with Dr. B. J. Mason, Professor of Cloud Physics at the surface, the ionosphere, and the thundercloud was appreciated. Specialists in delays in construction of his own similar experiment­ University of London in his recent book entitled, environmental electricity, so-called, now endeavour to link this vast circuit with al rig, conceived the even simpler scheme of bring­ "Clouds, Rain and Rainmaking": "This statement of others involving solar radiation and the newly-discovered Van Alle.n belts above, ing the cloud's charge to earth along the string of a Franklin's remained the only direct and reliable in­ and the interJial current gene1·ated by the earth's liquid core below. high-flying kite. His friend and contemporary, the formation on the subject for 170 years and even English scientist Joseph Priestley, tells of the historic today, we would wish to modify it only to the ex­ "However, we had to stop somewhere. We have chosen some simplified event ... tent of replacing clouds by bases of clouds." versions of some well-established theories in order to describe lightning. It is cwknowledged that these theories are possibly already outmoded by events, but "Preparing, therefore, a large silk handkerchief and we rest on our own theory - that any theory that helps an explanatio,n is a NATURE AND CAUSE OF two cross-sticks of a proper length on which to ex­ LIGHTNING good one". tend it, he took the opportunity of the first approach­ If you are interested in the theoretical aspects of the subject, we strongly advise ing thunderstorm ... The kite being raised, a con­ Although there hasn't been another Benjamin siderable time elapsed before there was any appear­ Franklin, the two centuries since his work ended you to obtain a copy of the Lockheed Field Service Digest No. 34, March, 1964. ance of it being electrified .. . at length, just as he have not been devoid of accomplishment. In fact, in Although it is unlikely that the Department will be able to satisfy all demands, we was beginning to despair of his contrivance, he ob­ the last 50 years we have seen a great resurgence of will try to assist by making two additional reproductions of the Appendix available served some loose threads of the hempen string to interest and progress in the sciences of meteorology at each of our Regional Offices so that a copy may be obtained on short term loan. stand erect and to avoid one another, just as if they and electricity which, through the use of airplanes, had been suspended on a common conductor. (The high-speed cameras, and a wide variety of electrical 10 SEPTEMBER , 1964 SE PT EMBER , 1964 11 and divides as it encounters vague "walls" of higher from the nose and wing tip similar to those discov­ resistance in the atmosphere. As this leader carries ered by Schonland growing from the ground in the the cloud's charge nearer and nearer to the ground cloud-to-ground stroke sequence. A picture taken a (or other electrical charge center), it violently accel­ split second earlier, just before the flash, would have erates ionization in the air surrounding adjacent shown another streamer, somewhat longer than those regions of low potential in the earth, to the point that luminous ribbons, similar to the stepped leader, From the nose and wing tip, emanating ' from the Figure 1 grow from the ground toward the cloud. These are propeller that was struck. commonly referred to as positive streamers. One of these streamers eventually contacts the oncoming Schonland states that three strokes per bolt is Artificial Lightning Dis­ stepped leader and a conductive path is established average, but it is not uncommon for as many as 14 charge to Metal Model between the two charge centres. This preliminary successive strokes to occur along the path established of Constellation process usually takes only some few thousandths of by a stepped leader. (It is the multiple flash process a second. which creates the impression of flickering which we have all noticed in large electrical storms). In fact by study of this phenomenon, Schonland has theo­ When the ionized (conductive) path is completed, rized that since the most frequently observed time there is a tremendous surge of electrons down the between such flashes is 3/100 of a second and the path, creating the brilliant flash and explosive sound we associate with the lightning bolt. This rush of most frequent velocity of the stepped leaders is 130 electrons quickly drains the charge from one portion miles a second, the average distance between ceJJs of the cloud, at which time a new stepped leader within a thundercloud is 0.03 x 130 = 3.9 miles. may grow from another nearby charge area in the cloud to this suddenly depleted area and, if the Although data gathered from cloud research indi­ original ionized path is still intact, another surge of cates that there is considerable variation in this electrons will occur. distance between charge centres, it is significant to aviation to note that it is always expressed in miles and not feet or thousands of feet - vast dimensions Figure 1 shows a stroke, produced artificially at indeed compared to even the largest aircraft. It is the Lightning and Transients Research Institute, to a recognized of course that aircraft do not normaJJy fl y metal model of a Constellation. This photograph is inside thunderclouds. However, the above dimensions included to show the positive streamers emanating do set the scale, and we might add that aircraft

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AVERAGE t' - DISTANCE - WITH IN CLOUD and electronic instruments has added more and more tionary high-speed camera invented by the English­ to the understanding of the nature and causes of man Sir Charles Boys, Schonland and his associates lightning.* found that a lightning stroke from cloud to ground F igure 2 is not simply one great spark of electricity leaping Perhaps the most significant single discovery in suddenly across the gap between two separated this period was made by Dr. B. F. J. Scbonland of charge centres, but instead consists of a complex se­ Typical Distances Between South Africa. Using an improved version of a revolu- quence of events. This sequence is described and il­ Thundercloud Charge lustrated in some detail in the Appendix to this Centers article, but a few brief words on the subject at this point are appropriate. *Regarding the nature of lightning, most research has necessarily been concentrated on strokes between clouds­ and-ground. Most of the findings in this article are there­ Photographs show that the first visible evidence fore concerned with this "type?' of lightning even though of activity is in the form of a "stepped leader," a most strikes to aircraft involve strokes between cloud faintly luminous trail of ionized gas which rea<:hes centers. However it has been established that the mech­ anism in all types of lightning strikes to aircraft follow downward from the cloud in distinct spurts (or steps) the ~ame general rules. about 150 feet in length. The leader twists, turns,

12 AVIATION SAFETY DIGEST SEPTEMBER, 1964 13 frequently intercept lightning strokes between dif­ when compared with turbulence and icing, which are ferent clouds where the intervening distance between the primary dangers from thunderstorms. Although charge centres far exceeds Schonland's estimate for lightning can cause damage of varying degrees to charge-centre distribution within a single cloud. aircraft, it is only rarely of a serious nature. This statement is supported by statistics recently released Probably the next most significant area of study of by the U.S. Air Force which indicate that, during the lightning has been the development of theories, from five-year period from January 1959 through Decem­ experimental work carried on by hundreds of scien­ ber 1963, there was only one major Air Force acci­ Figure 3 tists all over the world, regarding the basic process dent in which lightning was believed to be the prim­ whereby the electrostatic charges in thunderstorms ary cause. are built up and separated from each other. There Why Does Light­ have been perhaps two dozen prominent theories pro­ The record for commercial aviation is even more ning Strike posed to explain this phenomenon, based on a variety impressive. As far as we are aware, lightning bas yet Aircraft? of contributing causes such as the selective charg­ to be pinpointed as the primary cause in the destruc­ ing of droplets, freezing of droplets, shattering of tion of an all-metal airplane, but there have certainly drops, and many others. Laboratory experiments been two accidents in which the cause has so far not have proved that the processes described by many been established, and which could have involved of these theories can build up charges, but no theory lightning. Even allowing for these two cases as bas been accepted as adequate to explain the distri­ "possibles", the risk from lightning is undoubtedly •. there have been bution and build-up rates of charges known to exist at a level far below risks which are commonly ac­ repol'ts of strikes in thunderstorms. This, then, is still a very active field cepted as part of normal everyday living. very near but of meteorological research and is receiving the atten­ not actually to, tion of many research scientists. An Area Requiringj More Research. It has long been aircraft in flight. the practice in aviation circles, however, to explore ' avenues which could possibly lead to safer flight. There are certain similarities in the two aforemen­ PROBLEMS RELATIVE TO AIRCRAFT tioned accidents: As well as their possible connection with lightning, both of them seem to have also Of more immediate interest to the manufacturers involved integral fuel tank explosions, but the exact and operators of aircraft is the research work which mechanism of ignition has not been explained in has been done studying the relationships of aircraft either case. It should perhaps be emphasized that the to atmospheric electrical phenomena. These phen­ aircraft concerned were of different type and manu­ omena include such things as precipitation or "P" facture, and both of them conformed to or exceeded static (radio interference caused by the leaking off the established requirements for lightning protection. . . opinion most of charges accumulated by the aircraft from friction commonly held and/or passage through a charged region in the Considerable work has already been done towards in authoritative atmosphere); St. Elmo's fire (a visible corona caused determining what conditions are required within circles is that by accelerated charge leakage, indicative of high tanks containing various types of fuels to produce airplanes which charge gradients often portending a lightning stroke); combustible mixtures. However, this problem is so fly near thunder­ and the lightning strokes themselves. All of these complicated by the practical considerations of air storms will be phenomena may be encountered under similar con­ flows through the tanks, fuel sloshing and misting, struck only if ditions and often together. "P" static and St. Elmo's fuel weathering, etc., that it is apparent that much they happen to fire, however, are not necessarily accompanied by more research is needed if we are to expect designers pass near the lightning. to reduce the probability of the existence of combus­ natural stroke tible vapours within fuel tanks. As things stand path at the time Precipitation Static is very annoying and, by interfer­ now, we must assume that under some flight condi­ of its occurrence. ence with proper functioning of electronic devices, tions any tank containing any type of aviation fuel it can cause serious navigation and communication will contain explosive vapors and/or mists. This difficulties. This form of electrical interference in­ brings us to the question, "How do the combustible creases with airplane size and speed, and it is only vapors, when they occur, become ignited?" because of progress in detailed design of static dis­ chargers that these effects have now been reduced to There is still a very serious doubt as to whether an acceptable level. or not lightning could have produced the ignition of the vapors in the tanks known to have exploded in St. Elmo's Fire, as a visible evidence of electrical dis­ the two accidents mentioned above. The result of charge at a tolerably slow rate, is not a problem, thousands of lightning strikes to aircraft with­ does not cause any form of damage, and in fact out serious damage, leads to considerable scepticism serves in a positive sense as a warning that the that such newspaper headlines as "Airliner Struck by be advanced relating the two events. These facts airstream, perhaps lightning struck the vents, ignited environment is electrified, and lightning may pos­ Lightning - Explodes" are anything more than alone should demand the most thorough-going in­ the vapors, and the flame then propagated into the sibly occur. sensationalism. However, it has been established that vestigation possible. tank. However, in neither of the above accidents was the two events, lightning and the accident, occurred there found the common pit marking of a lightning LIGHTNING STRIKES These are generally consid­ more or less simultaneously in both accidents, and One thought which comes to mind is that, since strike in the vicinity of the vents, at least not close ered more of a nuisance than a hazard, particularly it is also true that reasonably plausible theories can the fuel tank vents are carrying vapors out into the enough to be within the zone which could contain

14 AVIATION SAFETY DIGEST SEPTEMBER , 1964 15 flammable mixtures. Also, it has been found that Nevertheless, there is no shortage of theories to CONCLUSION In a study made some time ago, KLM Royal only in climb does the vapor flow out of the vent in justify the proposition that airplanes induce strokes Dutch Airlines tabulated the strokes to each type sufficient quantity to support combustion, and, if the to occur that would not have occurred had the air­ Statistics of strokes to aircraft can be interpreted of aircraft in their fleet, then concl uded that: "These airplane is climbing, the flame almost certainly craft not been present. This poses a conundrum to indicate - or at least to hint - that aircraft may figures have no further meaning. They do not mean would not propagate into the tube against the out­ closely akin to "Which-came-first-the-chicken-or-the induce lightning strokes, but it is far from being flowing stream of vapors. egg?", and is almost as ancient. Some of these alter­ generally accepted as fact. There is also data that a certain type of aircraft is more prone to light­ native theories are discussed below and others in Part tending to refute this in that there have been reports ning strokes than any other type of aircraft. It only However, in recognition of the fact that fuel Two of this article; it should perhaps be mentioned of strokes very near, but not actually to, aircraft in means that there is a different system of operation vents - because of their function - inherently that many of the more plausible ones have been flight. of the planes, consequently, we have to be prepared seem to offer a possible source of ignition to light­ exhaustively investigated or will be investigated in for lightning damage if we operate planes on short the future in the interest of leaving no stone unturned. ning strikes, Lockheed recently participated in a study The opinion most commonly held in authoritative ru ns like the CV-240 at the moment." of the distribution of fuel/air vapors in the vicinity circles is that airplanes which fly near thunderstorms of vent exits. The new knowledge produced by this The most prevalent theory is that the airplane, will be struck only if they happen to pass near the program provides all designers and operators infor­ being a better conductor than the surrounding air, natural stroke path at the time of its occurrence. The problem then boils down to this: We must mation with regard to the zones in the vicinity of effectively shortens the distance between charge cen­ either stay away from lightning areas or we must vent exits which should be protected from ignition ters and thus triggers the discharge (stroke). Messrs. If we must operate aircraft in, or in the vicinity of, do what we can to minimize the damage that could sources. The study also suggests some possible areas M. M. Newman and J. D. Robb, of Lightning and thunderstorms, then we must expect that they will be possibly result from lightning strikes. On some com­ for the development of design improvements. Transients Research Institute, have this to say in a eligible for a strike throughout the period of time mercial flights, and quite frequently on some types of recent report on the matter: "Little can be done in spent in critical areas. Such areas may be defined as Another possibility is that under certain circum­ the immediate vicinity of an aircraft to control being in the vicinity of thunderstorms and at about military missions, the first alternative is out of the stances, explained later in this article, a lightning whether or not it is struck by lightning as the aircraft the freezing altitude. This aspect is discussed fu rther question and, whether we like it or not we are forced bolt could be swept beyond the extremities of the which is relatively small, can have little effect in in Part Two of this article. to accept the second. airplane onto such components as inspection covers determining the overall stroke path, which may ex­ for fuel gauges or filler caips. These may conform tend several miles." in every respect to present day standards of bonding, but there may not be sufficient conductivity between Another popular theory is that the airplane be­ the component and the primary structure to carry a comes charged either by friction or by passage direct lightning stroke. The installation design may through a charged region in the atmosphere, ap­ be such that the primary high-current paths produce proaches another charge center, and when it is close sparking inside the fuel tank. ~nough, either induces a stroke to itself or discharges itself to the cloud center. However, the charge which Other possible sources of ignition which require the aircraft is capable of carrying is so small com­ THE MIS SI NG LINK further study include such items as induced currents pared with that of the cloud that this could scarcely in conductors within the tank spaces, and direct pene­ be considered an important factor. About the most tration of tanks or tubes containing combustible that can be said for this theory is that the airplane's vapors. Some of these possibilities are presently care­ charge might conceivably be useful to an already With the approach of summer, some charter and aerial work operators will be preparing to resume fully considered in design but more research is re­ existing stepped leader, exploring the vicinity for banner towing operations over selected areas near our popular beaches and holiday resorts. It is timely quired to assure the adequacy of today's practices avenues of low resistance enroute to another destina­ to recall that last summer a potentially dangerous incident occurred when a banner was involuntarily and standards. Also, methods of predicting areas on tion. Newman and Robb say, "It should be noted the airplane which are susceptible to lightning must that all discharges which cause damage to an aircraft dropped while being towed by a light aircraft in the vicinity of Sydney. be more precisely defined. are lightning strokes which terminate not on the air­ craft but on the ground or on another cloud. So­ Banner towing operations are not permitted to take place directly over densely populated areas and The National Aeronautics and Space Administra­ called static discharges or general friction potentials one purpose of this restriction is to minimize the hazard, to persons or property on the ground, which which may be present on an aircraft from friction tion (NASA) has recognized the urgency of stepping could result from a banner breaking loose. Even so, a falling banner could still be a significant hazard to up this research and we can expect answers to many charging are not capable of damaging even thin air­ of these questions as a result. craft aluminium." third parties even over the lightly populated areas traversed between pick up point and beach display areas. It is not hard, for example, to imagine the possible dire consequences of a banner suddenly falling Another theory, which is being actively investi­ gated at present, is that the airplane leaves a trail of across a busy highway. On the occasion mentioned there was no resultant injury or damage to persons WHY DOES LIGHTNING STRIKE AffiCRAFT? ionized particles behind as it passes from one charge or property on the ground - but there easily could have been and, on the material side, there could have toward another. This trail of ions, slightly more con­ been a consequential liability for substantial civil damages. This is a question which to date has not been an­ ductive than the surrounding atmosphere, is theorized swered to everyone's complete satisfaction. The most to effectively shorten the distance between the charge The equipment, in this instance, comprised a length of manilla rope attached to the aircraft by a credible answer is that the airplane is struck only centers and thus trigger a discharge. This theory pro­ when it happens to be in, or very near (within ap­ vides a qualitative scheme of proper scale (a con­ releasable catch and terminating in a trailing hook, which in turn, engaged a loop of nylon rope attached prox. one wing span of), the natural path of a light­ ductor of sufficient length) but it is questionable that to the banner itself. The banner was lost when the manilla rope broke at a point just forward of the ning bolt. such a trail can, in fact, be sustained more than a trailing hook. few feet behind the aircraft. It is also significant that Most scientists agree that this answer is, in fact, strokes to the engine exhaust regions, which are quite satisfactory and could reasonably account for theorized to be the principal sources of ionized gases, The incident points to the need for careful inspection, before each operation, to ensure that towing all cases of aircraft lightning strikes where sufficient are rare compared to strokes to airplane noses, wing equipment and tow lines have suffered no damage or deterioration and are adequate for the task data exists and that have so far been investigated. tips, and empennages. demanded of them. Don't wait to find out the expensive way.

16 AVIATION SAFETY DIGEST SEPTEMBER , 1964 17 During a private flight from Nbill At this stage the aircraft's posi­ disadvantages, if not actual dan­ to Moorabbin, the pilot of a PA 24 tion had been uncertain for some gers, of a steep spiral descent in became lost and flew almost 95 mil­ thirty minutes and the pilot now close proximity to clouds, the high es off track before bis position was reported he was lost. Melbourne rate of turn used would probably finally determined. Operations immediately declared have toppled the gryo and disturbed the Uncertainty Phase on the air­ the compass to the extept that an Departing from Nhill at 0900 craft and set about trying to locate accurate heading, indication would hours, the flight proceeded un­ its position from the pilot's des­ not be immediately available when eventfully until after passing Stawell cription of the landscape. This was level flight was resumed. Visibility and beginning a descent to avoid an made more difficult when radio was hazy beneath the cloud and extensive layer of cloud. To steepen communication deteriorated and there was little outside the aircraft the descent the pilot made two des­ messages had to be relayed by other to indicate it was not on its previous cending orbits, the second at up aircraft in the area. Meanwhile the beading. The pilot then mistook to 60 degrees of bank and levelled pilot had descended to 1000 feet Trawalla on the Ballarat-Ararat se­ out below the cloud at 2,500 feet above the terrain to avoid turbu­ tion of the railway for Clunes and on what he believed to be his lence beneath the cloud and after this both consolidated his belief that original heading. being forced to divert to the west he was on track, and provided evi­ to clear a range of hills, resumed dence for rationalizing the non­ Clunes, midway along the rail­ appearance of Ballarat and the way between Ballarat and Mary­ what he thought was a southerly unexpected sighting of the first lake. borough was next check point, es­ heading. On reaching the coast In assuming that the map was timated at 1000 hours, and when at some minutes later, he turned and flew eastwards and after another wrong, the pilot of course fell into 0959 the aircraft passed over a the age-old error of inexperienced small town on a railway line, it was fifteen minutes, reported over a lighthouse. The aircraft was in­ navigators. Since no fault could assumed to be Clunes. From here, subsequently be found with the air­ Ballarat should have been visible structed to orbit while Melbourne Operations attempted to identify craft compass, it is not entirely clear about ten miles to starboard and why the pilot did not discern the although the pilot was a little con­ the lighthouse and from the pilot's description, one of the air traffic error in his heading after emerging cerned when it could not be seen, from the turns. The pilot believed he he attributed it to the haze which controllers on duty recognized it as the Cape Otway light. An air­ had resumed his original heading was restricting visibility beneath the but stated later he was puzzled by cloud. He was also unable to flash telephone call to the lighthouse confirmed the aircraft was circling the consistent error of 40 degrees in recognize a lake which now ap­ the headings flown while following peared on his port side but con­ there and Melbourne then instruct­ ed the pilot to proceed to Moorab­ the coast to Cape Otway and thence cluded that it could have been form­ to Geelong. It therefore seems pos­ ed since his three year old map was bin via the coast and Geelong. When over Geelong about 30 sible that the pilot had been main­ published. In any event, he reason­ taining track on the directional ed he must still be very close to his minutes later however, the pilot be­ came doubtful whether he could gyro and did not notice its setting intended track and that he should was disturbed during the steep soon sight Port Phillip Bay. still reach Moorabbin with the re­ quired reserves and decided to land turns. Visibility then seemed to be better at Grovedale. The Uncertainty The poor visibility also played a to starboard and the pilot turned Phase was cancelled when he tele­ significant part in this incident. The in this direction, expecting that it phoned Melbourne Operations from pilot was unable to recognise any Cape U l\•"c ,~' .,1' I would help him pin-point his Grovedale. landmarks through the haze ahead I position. He flew this heading for but conditions looked clearer to I some few minutes and then sighted starboard. He turned in that direc­ I a broad expanse of water in the ANALYSIS tion, thinking this would take him I distance. Assuming this to be Port It is evident that the pilot's lack in the general direction of Ballarat. I Phillip Bay, he al tered the heading Instead of approaching familiar I of experience was a contributing to intersect what he thought was factor in this incident. He had held landmarks however, the aircraft was the light aircraft lane of entry be­ a Private Pilot Licence for less than now moving further away, and the tween the Melbourne and the two years and had logged only about chances of pin-pointing a position Laverton - Point Cook Control 150 flying hours. were becoming accordingly less. Zones. As he approached however, It has been found that when in­ LEGEND it became clear it was not Port His navigational difficulties experienced pilots encounter map­ Phillip Bay but a large lake that obviously began with the descent to re~";. ng difficulties they sometimes was entirely unknown to him. avoid the cloud. Apart from the I.end to fly where they think their I VICTOR I PROPOSED TRACK TASMA~ S EPTE M BER , 1 964 19 I I APPROXIMATE TRACK I FLOWN I. I I 1 I track lies rather than rigidly adhere COMMENT: 4. Mentally plan ahead of your flight plan, looking well ahead to a compass heading, and this This incident bears out several and to either side of your tendency may have lead the pilot rules which experience has shown OVERSEAS ACCIDEN'fS IN BRIEF track for those features which further astray once he had un­ to be vital to accurate VFR navi­ your map tells you must be wittingly turned from the track he gation: knew. The fact that no changes of present. Know where you are In the June issiw of ou1· Digest, we published sevenil b'rief swnniaries of cifrcraft ciccidents heading were logged and he was I. Prepare an accurate flight plan on the map all the time. which had occurred in other parts of the world, Space limitations prevent the description of a later uncertain of some of the head­ making use of the meteoro­ la1·ge nnmber of overseas accidents in detail, but there is no doiibt that many contain valuable ings flown again suggests that his logical information service 5. Constantly check your direc­ lessons that can be applied to operations in Aiistralia. We now present a further selection of attention to the compass was in­ which is provided fo r your as­ tional gyro against compass summaries cincl it is intended that these will become ci regula1' fecitm·e of the Aviation S nfety adequate. Thus, when he first sistance and safety. heading. Remember to allow Digest. caught sight of Lake Corangamite, for deviation and that you he had no hesitation in assuming it 2. Prepare your maps accurately must fly accurately to obtain was Port Phillip Bay. marking the track to be flown. an accurate heading indication ing with the undercarriage retract­ Th e problem has been co ncern­ Drift lines and markings of from your compass. Collision During The aircraft's position had been distance/time intervals be­ ed. The crew could not sub­ ing the Department for some time uncertain for half an hour by the tween obvious pin-points are Approach sequently recall if they had used and an Air Navigation Order is time the pilot called for assistance an advantage. Study your H you follow these rules you the "before landing" check list. now being issued requiring that (C.A.B.) and the task demanded of the route before commencing your should not get lost, but if during a After fl ying a conventional traffic on certain aircraft types, the audible w a rning w ill operat e not Search and Rescue Organization flight. flight you do become unsure of your pattern at an uncontrolled airport, was a formidable one. Poor com­ position, keep to your flight plan a Cessna 210 turned on to final DC-8 only when the throttles are re­ munication with the aircraft made 3. Fly to your flight plan accur­ until you can positively identify a approach and collided with a tarded to the norma l land ing it even worse. It was fortuitous that ately, making alterations to pin-point. H your .flight plan has Cessna 172 making a straight-in While approaching for an en approach position, but also when one of the officers on duty knew headings and time intervals as been accurately calculated and you approach. The propeller of the 210 route landing in the course of a the wing flaps a re ext ended the Cape Otway area and was able required, but only upon con­ have flown accurate headings and struck the rear fuselage of the 172 scheduled passenger flight, the beyond the a pproach / cl imb con­ to identify the lighthouse from the clusive evidence obtained air speeds, you should not be far severing the tail assembly. The crew of a DC-8 completed the figuration if the undercarriage is pilot's description. through accurate map reading. from track. 172 crashed to the ground out of "before landing" check list as far not down and locked. control, killing the pilot, but the as the "gear extension and check" 210 was able to continue to a safe item. The aircraft was being flown landing. Although the pilots could by the co-pilot from the right hand :Faulty Maintenance have seen each other's aircraft while seat and at this stage the crew's establishing their final approaches, attention was diverted to other Control Cables Reversed they did not do so. However, had traffic in the circuit. Forgetting the After a Cessna 150 had taken Failure Forestalled the pilot of the 172 conformed to underc_arriage, the crew continued off and climbed to about 100 feet, the aerodrome traffic pattern, it the approach. The warning horn While taxying out for take-off at a capital city airport, the captain of a Viscount noticed a slight it banked sharply to port, the nose would have given him ample time sounded as power was reduced vibration similar to but somewhat less than what is usually felt when the brakes are applied towards the dropped and the aircraft crashed to see 'the other aircraft already just before touch down and the end of a landing run. The vibration was present despite the fact that the brakes were off, so the captain to the ground. The pilot was in the circuit and make a safe undercarriage was immediately decided to conduct a further check by turning and taxying back towards the terminal. It then became seriously injured and the au craft approach to land behind it. selected "down", but it had only evident that the port main wheels were dragging, although only slightly as little asymmetric power was destroyed. Investigation of the (C.A.B.) begun to extend before the aircraft required to compensate for it. The aircraft returned to the tarmac for the wheels to be checked by the settled on to the runway and slid wreckage showed that the aileron maintenance staff. to a stop on the bottom of the cables were installed in the reverse :Forgotten fuselage. sense. A 100 hourly inspection had When inspected, it was found that the port outer wheel was excessively hot but there was no sign (C. A .8.) been performed on the aircraft -of smoke or obvious damage. After it had been removed however, it was found that the wheel bear­ Undercarriages before the accident and the main­ ings had disintegrated and parts of the brake assembly had been damaged. Comment tenance personnel responsible stated that they had found the aileron Lockheed Electra These two accidents, particular­ cables crossed and had corrected In his report on the incident, the captain emphasized that the warning symptoms which led him to ly that involving the DC8, amp ly them. However, as there was no m ake the additional taxying check were very slight indeed and that at no time did he suspect anything Preparing for a landing at the illustrate the Department's view evidence of any aileron malfunction more serious than a binding brake. The pre-flight inspection of the wheel assemblies had revealed no end of a night flight, the Electra that on modern turbo-prop and before the inspection, it was con­ evidence of the bearing failure and practically no drag was felt while taxying out to the end of the run­ crew completed the "descent" check turbo-jet aircraft, undercarriage cluded that improper maintenance way in use. Had the taxying distance been less, as would have been the case if another runway were list and reduced power. The land­ w arning systems actuated by being used, it is most likely that the bearing disintegration would have escaped detection. A complete ing gear warning horn sounded and inspection had been responsible throttle movement a lone do not fo r the accident. failure might have then occurred either during the take-off or the subsequent landing. as the throttles were retarded but provide sufficient warning of an (C.A.B.) it was silenced for the descent. The " unsafe to land " underca rriage By recognising an abnormal condition at an early stage, the captain avoided what could have be­ crew then became engrossed in their position. As in the case of the Comment come a serious hazard. respective duties and the captain DCB , the w arning comes far too In A ustralia, all work perform­ continued the approach and land- lat e for a ny remedia l action. ed on the flying control syst em of AVIATION SAFETY DIGEST 2 0 SEPT EM BER , 1 964 21 -1- an aircraft must be subjected to Nothing was found to suggest aircraft to cartwheel. Both pilots Ailernn Controls Severed two independent inspections before any engine or control failure had and five of the 43 occupants were f'.. the aircraft is cleared for flight. occurred before the aircraft broke fatally inj ured in the crash and While engaged on an extensive ANO 105.1.0.2.8 sets out the De­ up, but an inspection of the cabin subsequent fire. It was determined cross-country flight, the pilot of a partment's requirements in this re­ heating system disclosed a three­ that the accident was caused by a Cessna 310 was warned of severe gard. This accident emphasises q uarter inch hole had burned again the extreme importance of loss of control in turbulence frontal conditions and thunder­ applying these dual inspections through the exhaust muffler wall associated with a severe thunder­ storms across his intended route. with meticulous care. into the heater muff. There were storm. Despite this the flight was con­ also several other breaks in the (C.A.B.) tinued and the aircraft later crashed exhaust muffler around the spot in the area oE frontal activity. welds. Post mortem examination of Fatal Stall After Take-Off the pilot's body revealed a carbon Friendship Stalls on Final Examination of the wreckage Soon after becoming airborne on monoxide saturation sufficient to cause unconsciousness at an altitude Approach showed the aircraft had struck the a take-off for a trans-Atlantic ferry ground in a flat attitude with a of 7,500 feet. A line squall passed over a con­ flight, a Piper Twin Comanche very high vertical speed and little (C.A.B.) trolled airport just as a Fokker F27 climbed rapidly and assumed an forward motion. Both tailplane increasingly steep nose-up attitude. was making a final approach to surfaces had failed in upward bend­ It then stalled, and with very little land at the conclusion of a schedul­ ing and the outboard portions had forward speed, fell heavily to the Accidents in ed flight. After crossing the run­ ground in a level attitude. Both way threshold, the aircraft encoun­ separated in flight. The investiga­ occupants were killed on impact. Turbulence tered severe gusts and visibility was tion found that manipulation of reduced to almost zero. The air­ the controls could not fail the tail­ Fatal Take-Off Temporary long range fuel tanks craft stalled and dropped heavily on plane of a 310 without first failing the wings and it was concluded that had been fitted in the cabin in place A Martin 404 began a take-off to the runway at a relatively slow of the rear seat. The investigation forward speed. The impact sheared the tail structure had failed when just as a thunderstorm was moving At Canberra recently, an engine of a Cessna 3 10 caught fire could find no record of inspection both wings off between the fuselage it encountered turbulence forces over the airport. Immediately after while it was being started for a flight to Cootarnundra. A loud or approval for this installation and lifting off, the aircraft entered heavy and the engine nacelles and the air­ beyond its design strength. (C.A.B.) explosion inside the engine nacelle caused the cowlings to be it was calculated that the centre rain, hail and severe turbulence. craft came to rest on one side of the blown open and the fire followed, but it was quickly extinguished of gravity at take-off was about four The aircraft was thrown about, runway with the fuselage intact. by the fire crew and the damage was confined to the cowlings inches aft of the authorized rear dropping first the left then the right The passengers and crew were un­ ~ themselves. limit. As well, the weight of the wing. It levelled out momentarily, injured and were able to leave the aircraft without difficulty. Strnctural Failure in Flight "'{.. aircraft was 350 pounds in excess then the left wing dropped again At the time the engine was hot and the pilot had at first of the maximum overload permit­ and struck the ground, causing the (Fokker B11//eti11). While flying at 1500 feet an tried to start it without priming. When the engine would not ted for a long distance ferry flight. Aeronca 11 suddenly encountered catch, he primed it for two or three seconds and the explosion a brief but extremely severe area occurred on the next start attempt. In this configuration, an uncon­ of turbulence, similar in character trollable nose pitch-up condition to vortex turbulence. Simultaneous­ Investigation revealed that the aircraft was standing tail would occur unless the airspeed ly, the pilot heard a noise in the air­ into wi nd at the time and this fact, in combination with the hot was allowed to build up well above frame structure and lost all aileron and over-primed engine, had allowed the nacelle to fill with fuel normal and very close control control. He managed to guide· the vapour. When the engine fired, the exhaust flame in the entrance maintained during the critical aircraft to a crash landing in the to the augmentor tubes ignited the vapour inside the nacelle, phases of take-off and climb. tops of some large fir trees, but blowing out the cowlings and starting the fire. (Ministry of A viatio11) was seriously injured when it crash­ The incident is by no means isolated. In December, 1960. ed to the ground in a steep nose­ the Digest reproduced a warning issued by the Beech Aircraft down attitude. Corporation on the dangers of fire when starting augmentor tube Pilot Overcome by Carbon equipped aircraft, and in 1961 the Cessna Aircraft Company sent Examination of the wreckage re­ Monoxide a Service Letter to all operators of Model 310 aircraft setting out vealed that the aileron cable link the precautions that should be taken against this possibility. A n hour after it had departed plates above the cabin had pulled The problem is not confined to Cessna and Beech aircraft on a travel flight at 7,500 feet, a out, severing the aileron control but applies equaJly to the starting of all aircraft that are fitted PA 24 was seen flying low at system. The failure was attributed with augmentor tubes. Pilots can do much to eliminate the abnormally high speed. It then to turbulence-induced loads acting problem by at least observing the two golden rules of avoiding disintegrated in flight and the on the aileron surfaces. engine flooding, especially with a hot engine, and ensuring proper wreckage was scattered over half (C.A.B.) ventilation of the nacelle area by avoiding, as far as possible, a mile. All five occupants were killed instantly. downwind or excessive cross-wind start-ups.

SEPTEMBER, 1964 23 22 As expected, the ASI reading increased and ft uctuations continued even after the aircraft had I trimmed back on the autopilot. The speed con­ emerged into the clear again, and the crew contacted tinued to rise, and soon (perhaps 10 seconds) it their company by radio to request that the fuselage indicated 365 knots, with VSI showing over 4,000 be checked for ice, especially around the static ports, fpm climb, and a very high Mach reading. There as soon as the aircraft arrived. It was found that was slight turbulence and my immediate thought even though the aircraft had been flown in tem ­ was updraft associated with the storms. I pointed peratures of + 20°C. for five or six minutes and this out to the flight engineer and called for 89 the ground temperature was + 30°C., the aircraft per cent High Pressure Compressor R.P.M., and still bad ice on the fuselage, though the static ports then asked for the copilot's airspeed reading. He bad cleared. reported I 85 knots, falling. In relating this experience, the captain wrote: On bearing this, I disengaged the autopilot, put the aircraft in level attitude and called for "What we bad was a very cold-soaked air­ 95 per cent. H.P. Compressor R .P.M. Then we craft descending through rain which immediately began a cockpit check! At this point I did not froze on contact with the skin of the aircraft. We know what was wrong and what instruments to have had this to contend with in runback on the believe, but I did have confidence in the horizon. wing in the past, and it remains a problem when There was a lot of negative 'g' during the nose using wing beat. drop to level fl ight, but I must point out I was not conscious of a particularly nose-high attitude. In "Since this experience'', the captain added, a few seconds the flight engineer fo und that the "I've advocated heating the area around the pitot-bead heat switches were in the 'off' position. static ports to prevent such a situation occurring. They were put 'on' and in no time the panel With the jet, the icing problem has been cut to returned to normal and my ASI was reading 220 a minimum in the areas of flight where in the knots or thereabouts. The height loss was 1500 past we bad our greatest exposure. But the feet. incident just mentioned is one that has come about with the jet. In fact, in over four years Later, when everything was back to normal, of jet experience, it was the only time I have I began to wonder if this might have happened lo seen icing become a problem and it was where those aircraft involved in loss-of-control incidents. you'd least expect it ... in the tropics!" The followi ng would seem to me to be pertinent:

1. In my own particular incident, assuming the copilot's ASI to be correct (not necessarily ICE DISTURBS AIRFLOW OVER true), it would only have taken a moderate ST A Tl C PORTS amount of turbulence or a turn to bri ng on a low-speed stalJ. The jet flight departed at night in extremely cold but clear weather conditions. The takeoff weight 2. How do you recover from a stall at night and was just under 290,000 lbs., and the critical speeds In bulletins we have received recently from the Flight Safety Foundation in the in cloud without ASI? had been computed as Vi-132 knots. VR-149 knots United States there are three reports dealing with pilot-static icing on heavy turbo­ and Vd62 knots. The captain was fl ying the air­ jet transport aircraft. In two instances, the loss of an accurate airspeed indication 3. What are the likely manoeuvres to be ex­ craft from the left hand seat and the story is told created a difficult and hazardous situation. The pilot's accounts of these i.ncidents pro­ pected in such a recovery?" in his own words: vide ·some serious food for thought and emphasize the importance of cross-checking the ff,ight instruments on jet aircraft. They should be of particular interest to pilo ts who STATIC PORT ICING " Power was set on the brakes. The strong are .now converting to jets. cross-wind took some of my attention, but never­ The airline jet bad been cru1smg at 37,000 feet theless it appeared to me that it took longer than for several hours, with an outside air temperature normal to reach y , speed, and I took a quick PITOT-HEAD ICING speed. At about 28,500 feet we were between of minus 50°C. Descent was started towards an air­ glance at the power instruments to check that two large and very active storms that were some port where ground temperature was + 30°C. Every­ power output was normal. After completing a night flight over a route on 25 miles apart, and we were in cloud or over­ which considerable thunderstorm activity was en­ thing was normal at first, but at about 18,000 feet hang associated with the storms. Engine heat the aircraft entered moderate rain which continued When we became airborne, I was surprised countered, the captain of a large jet gave the follow­ was on and there was visible precipitation and ing report of his experience: down to 6,000 feet. At about 10,000 feet both the to see that we had used more runway .than I had static on the wind-shield. The cloud thinned, captain's and copilot's altimeters and rate-of-climb anticipated. I climbed out maintaining a pitch "During the climb I was completely en­ then the moon and stars became visible. I called indicators began to fluctuate, and at first the crew attitude of 10° nose-up. When I looked at the grossed in watching radar, heading, and air- for engine heat "off". thought it was caused by the rain. However, the airspeed again, I was surprised to see that we

24 AV IATION SAFE TY DIGEST SEPTEMBER , 1964 25 only had 160 knots. Normally the aircraft should 20 knots higher than the captain's ASL We tried OUT have accelerated to 175 by that time. What was alternate static on both the captain's and the more surprising was that the rate of climb was un­ co-pilot's instruments. This made the indica­ steady, fluctuating from 2000 ft./min. climb down tions of the captain's and the co-pilot's the same, ~ Jj to zero and then up again. It went through my but I knew they were both wrong since the I mind that there probably was turbulence due to vertical speed indicators fluctuated and the air­ OF ·I the strong wind, but I began to feel a bit unhappy. speed and Mach figures did not correspond with Nevertheless, I lowered the nose a bit to increase the power settings. the airspeed and quickly verified pitch attitude on the standby horizon. The speed increased to We levelled off at 31,000 feet (on the co­ 170 and by that time we had reached the noise pilot's altimeter) and I engaged the autopilot, UEL! abatement height of 700 feet, so I reduced power, setting power according to the graphs. We flew but by then I began to realize something was this way for a while, having removed the pitch really wrong so I put power back on again. trim by override and pulling the circuit breakers. The autopilot could not be used in the altitude I looked outside once more to verify pitch hold mode. We had asked A TC to provide attitude and checked the horizons. By that time additional vertical separation. After about one I saw that we were lower than we should be hour 15 minutes the indications began to return and climbing rather flatly, so I pulled the nose to normal, and after one and a half hours every­ up, but the airspeed indication of 170 made me thing was O.K. again. put it down again. The vertical speed still fluctuated and the rate of altitude increase on There is no doubt that this could have been the altimeter seemed much less than it should be. a very dangerous thing if the weather had not At 1800 feet I asked for flaps up when the speed been so perfect. I believe that what really saved showed 185/ 190 knots. Afterwards this may seem us was the fact that I was sure right from the to have been a questionable decision, but lots beginning that the horizons were O.K., which of things went through my mind including the I was able to verify by simply looking outside, accidental lowering of full flaps during the take­ bein" over a well-lighted area. It is hard to put off. into "'words how confused one can feel taking off Not long ago, the pilot of a PA endurance, he still failed to recall peared ac ross the fli ght path. He 24 was forced to make a wheels up the previous flight. One tank in We had been instructed to turn left at at night if the airspeed is much lower than one retracted the undercarriage in the landing in a paddock when fuel be­ fact became exhausted shortly be­ 3000 feet and report, and when my altimeter expects and an indication of a descent on the hope of clearing the wires but lack came exhausted only five miles short fore reaching Wellington, and after indicated only 2000 feet the co-pilot to my surprise vertical speed indicator is seen together with of airspeed forced him to dive be­ of the destination. T he aircraft had landing and disembarking his pas­ reported 3000 feet. I turned left more or less in­ an insufficient increase in altitude on the alti­ low them and make a wheels-up just completed an extensive all-day sengers, he thought seriously of re­ stinctively, but I later realized that I had done meter while power and pitch attitude are O.K. landing. charter trip from Moree, N.S.W., maining there for the night. Never­ so to proceed towards the well-lighted city to In this case my thoughts turned to horizon and after disembarking his pas­ theless, on the basis of his flying keep visual reference since by that time the failure at first, and it is hard to say what I might sengers at Wellington late in the times throughout the day, he rea­ indications of the pressure instruments were so have done if I had not had visual reference. day, the pilot was making a 15 COMMENT confusing. For instance, when the captain's rate T his incident could have some bearing on a few soned that he must have sufficient minute ferry flight back to his base of climb showed 2000 ft./min. up, the co-pilot's unexplained crashes soon after a night take-off". fuel to safely reach Dubbo. Dark­ This accident occurred because at Dubbo Airport. ness was approaching so without showed 2000 ft./min. down. the p i lot d id not ensure that his Investigation of this incident revealed that prior waiting to inspect the level in the On the morning qf the flight, the a ircraft was carrying sufficient to departure, the aircraft cabin had been heated tanks, he departed for the 15 minute I thought of landing straight away, but th ~ pilot carried out a daily inspection fuel. His failure in this respect from an external source after the cabin water tanks fli ght to his base. high gross weight and strong cross-wind stopped of the aircraft but omitted to re­ was a contravention of Air Naviga­ me from doing so. We proceeded east, climbing had been re-filled with relatively cold water. When tion Regulation 225( 1 ){d). The this water warmed up and expanded, some of it move the fuel tank caps to make a E vidently the pilot was not com­ at 300 IAS on the captain's instrument. By that most surprising feature of the ac­ spiJJed out through the tank vents while the aircraft physical check of the contents. The pletely satisfied for his mind contin­ tin1e there was a constant difference of 1500 feet cident was the pilot's extensive was still on the ground. T he vent of the forward fuel gauges showed full on both ued to dwell on the fuel situation, between the captain's and the co-pilot's altimeter. experience, and the fact that he water tank is located almost perpendicularly above tanks and having forgotten that he and only a few miles short of D ubbo had previousl y en joyed the reputa­ T hen something even more disconcerting the static openings on the port side of the fuselage, had not refuelled since making a be suddenly recollected the earlier tion for taking pride in the conduct happened: there was a funny feeling on the and as the outside air temperature was minus 20°C, 30 minute fl ight two days before, he flight. But it was already too late. of his flights. It is d ifficult to elevator control. I felt repeated trim changes and the overflow froze as it ran down the fuselage, form­ set out with the impression that the Almost immediately afterwards the understand how a professiona I then I saw that the pitch trim compensator had ing ice ridges near the static ports. In flight, these aircraft had its full fuel endurance fuel pressure gauges fell to zero and pilot could take a chance of this extended almost to maximum. At that time I also ridges created eddies in the airflow, causing pres­ of 240 minutes. the engine failed. nature. N evertheless, it clearly noted there was a big difference between the sure fluctuations in the static lines system. It was also Towards the end of the day's fly­ In the gathering dusk, the pilot demonstrates that no amount of Mach - meters; the captain's indicating Mach found that the manufacturer had previously recom­ ing, the fuel gauges were indicating selected a field and lowered the experience or a bility can justify 0.75, but the co-pilot's indicating Mach 0.84 as mended re-locating the static vent openings on this abnormally low. and although the undercarriage for landing, but late taking anything for g rant ed in near as I could see. The co-pilot's airspeed showed type of aircraft, but this had not been implemented. pilot began to be doubtful of the in his approach a power line ap- flying.

26 AVIAT ION SAFETY DIGEST SEP TEMBER, 1 964 27 My thoughts for A SAFE FLIGHT

l. am physically, mentally and aeronautically prepared for the flight involved, a flight w hich know wi ll be in keeping with safe and approved operating procedures.

2. know t he safe operating techniques of my aircraft, and I sha ll make every effort t o assure that my aircraft is in a good state of airworthiness.

3. know my own limitations.

4 . will maintain the highest degree of vigilance throughout the conduct of my flight, being always mindful of the risk t o hµman lives and property while I am at the controls.

5 . I know the performance capabilities and Ii mitations of my aircraft and have studied and reviewed a ll applicable emergency procedures to the extent that I can perform them under the pressure of any emergency.

6. I have a thorough understanding of existing weather conditions in my area of operat ion, and I have given considerable thought to alternat ive actions should there be an unexpected change in the weather conditions w hile I am airborne.

7 . wi ll stay "ahead of my aircraft" and be in control of every phase of the flight.

8. w ill make a precautionary landing as soon as possible when any cond ition or occurrence ca uses me to deem it inadvisab le to continue my flight. Unfavourable weather c.o nditions, unfavourable w ind conditions, a fuel state lo wer than that consistent with safe flight planning, a condition or discrepancy in my aircraft or powerplant that I do not understand, shall be predetermined conditions for discontinuing the flight.

9 . I will always keep in mind that the flight does not end until the aircraft has been brought to a st op and the engine(s) shut down.

1-0 . I w ill make appropriate not es and discuss with appropriate persons a ny mistakes or errors in judgment pertaining to my flight even though they may have been unobserved by others. This action may benefit other pilot s or disclose an area for improvement in my piloting ability. .. I 11 ... I /:-:. ('l£,( J/<-. l \. ' ' IC .' ' '"""") (" e,c,, /u/~ Civil Aeronautics Board Bureau of Safety. L0\\7 FLYING

T he Frigate bird has a body the sizP of a chicken - but a wing span of seven feet. T hese wings can easily get caught in bushes and trees. W hen t hat hajJ/Je 11 s, he's had it. For this reason the Frigate bird never f Lies low except w hen on operntions - in search of food. 28 AVIATION SAFETY DIGEST