c I, SA- I rCll 'File No. 1-0064 CIVIL AERONAUTICS BOARD SAFETY BUREAU

ACCIDENT INVESTIGATION I

. " Adopted: September 16, I947 Released: September 17, 1947 .-UNITED AIR LINES, INC.,-LA GUARDIA FIELD, N€W YORK-MAY 29, 1947 The Accident At lS5 the engines were started, and Flight 521 requested taxi bstructions the tower. A' United Air Lines' C-M, WC 3OO&R, Flight from Clearance was given to Runway the wind being' 521, craskied while atteqMn5 a Wce-off from 13, reportedby the tower as south, variable to Ia Guardia Field, New YorK, at approximately southeast, 20 miles hour. taxiing 1906,l May 29, M7. Of the 48 occupants, 43 per After out, the parked approximately 50 were killed, four sustained serious injuries, was feet adjacent to bway and, according to end one, the pilot, received only minor inju- 18,3 Captain Baldwin, the engine "rw-up" and "take- ries. The aircraft was denolishkd by impact and partially consmd by fire. off check" were then accomplished. Captain Baldwln held at this point, approxi- History of the FI ight mately six to seven rninutes. An unexpected dif- ference occurred between Nm and Airway Traffic United Air Lines' night 321 of May 33, 1cX7, Control with ref'erence to his clearance which was scheduled to depart from La Guardia for had to be strai@ened out before deprture. At Cleveland, Ohio, at 1W. Captain Benton %ld- the tower delivered the corrected clearance win, the pilot, reported at 1730 in United's from Airway Traffic Control. dispatch office, consulted the caspany meteor- Meanwhile, black thunder clowls and lightning - ologist, and studied route weather data. He were visible west of La Guardia. The squall found that thunderstorm condition. existed which line was breaking then over Hell Gate, some two L_ resulted from a cold front a.;d Drefrontal squall to three miles west of the field. Air crews line, tnen located west of the New York area. hastened to land or take off before being over- The flight plan based on this weather informa- taken by the approaching storm. Northeast Air- tion and prepared bj the Captain and his co-pi- lines' Flight 28, a DC-3, took off f'rom Runway lot, Robert E. Sands, specified instrument 18 at 1901. Fvnericm's Flight 250, a DC-3, flight at4,O feet via Newark and Youngstown landed a minute later on the same runway. Pan to Cleveland with Detroit (Willw Run), Michi- American's Flight 58 was cleared to land on Fluri- gan, as an alternate. way 18, and Transcontinental ,% Western Air's At the time that Captain 3aldwin consulted Flight 815 was cleared to land followine; Pan the company meteorologist, reports issued by American on hiwas 13. Wind was mw beinq re- both the United States Weather Wreau and the ported by the tower south variable to southwest, company meteorologist were available forecastig 22 miles per hour. At l'm4, United's Flight 521 that the prefrontal squall line above referred advised: "Ray for take-off." The tower oper- to would break over la Cruarilia Airport at 1900. ator asked whether the flight wished to wait out Captain !Mdwin testified that he had not seen the storm on the ground. Captain I3aldwin an- ._ these reports and that he had not been concerned swered: "1'11 take off." The tower then ad- with the5 inasmuch as his scheduled departure vised Captain 3aldwin: "Cleared for imnediate time was L8Y0.2 The flight plan, filed by take-off, or hold; traffic on final ap-aach Captaln %ldwin, was perfhctoriljr anproved by north of Riker's Island." em assistant dispatcher without comnent. Flight 321 taxied from its parked position, Serviclng and loading of the airplane WBS de- rolled onto Runway 18, and without puse or hes- layed, and departure time was set back frm 1%0 itation accelerated for take-of'f. Pie to l(W0. At pxssepgers w.d crew boarded. were advanced. Air speed increased to above 20 Accordine to the weigii? manifest, the fliat's miles per hour. Captain Baldwin testified that totd gross weigiit was fi0,319 pounds, the docu- he aplJlied back pressure to the control colunn, mnt listing 41 passengers, a crew of four, 1300 3me control tower operator was posltlve that gallons of gosoline, and 2,575 pmds of cargo. clearance was orlgfnally glven to Runway 13 and that - only arter Runway 18 had been requested by Captail! lAll times referred to horeln are Eastern Standard Baldwin, was the ship cleared to Runway 18. Captaln and are based on thc 24-hour clock. Baldwln stated that he was originally cleared to Run- way 18. It should be noted that the cholce or run- 2 The scaeduled departure tlme was actually 1840. ways Is a reswnslblllty of the pllot. The tower but Captain Ealdwln testlfled that it was 1830. "clears" only on t.he basls of trarflc conslderatlons. -\ I

2 c Accidmt 0 nvesti gat i on Report but the “feel“ of the controls was “heavy“h ami Both Captain BaMwJn sud First Officer Sands the aircraft did not respond. As the aircraft had received routine um&ical examinations. !hey continued toward the boundary of the field, had no known pbysicdtdeficiencies, and were in Captain Baldwfn decided to disconthe his take- good physical comiit&n for flight duties. off: About 1,OOO feet *an the south end of the The aircraft, hT-, aC+DC, was com- rinway he applied brakes, ordering the co-pilot pletely destroyed. Rhe -elage was crushed by at the same time to cut the engines. A ground- impact, end partial% cans& by fire. All loop was attempted by heavy application of left sea&, with the exce@im of the hostesses‘ brah. The aircraft, however, proceeded to roll seats, were found &&mtred from the floor. Flre straight ahead. men, with both brakes locked extinguishers were f&mdIn the proper racks and it continued over the remainder of the runway, not discharged. crashed through the fence at the airport bound- The arh?luhe empennage control sur- ary, and half-bounced, half-flew across the faces sustained very Rittle impact 8-e though Grand Central Parkway. The aircraft finally they were partially ccronsund by fire. No struc- cmto rest imxiiately east of the Casey Jones tural failure or mecfbmlcnl malfunction was School of Aeronautics, a distance of 800 feet folml. fran the end of Runway 18 and 1,700 feet from The cockpit was MIL relatively intact. The the point at which brakes were first applied. floor had been torn as a result of the failure It was almost inmediately enveloped in flames. of the nose gear, amf the forward upper section Only Captain Baldwin was able to ‘escape before of the was mnsmd by fire. No relia- emergency fire equipnent and rescue arrived. ble evidence was obhined from the position of Other survivors, one of whom later died, were the controls. Impact tension on the cmtrol assisted out of the wreckage within a period of cables and acceler&iim forces on tile controls 2 b, 3 minutes af‘ter the crash. themselves during cmse of the crash my have altered their ’he position. ;The gust lock Invest i gat i on reel was located, ami! the gust lock tape found reeled-in.’ A ballst sand bag was fomd be- Benton Baldwin, age 38, graduated from tAe tween the gust lockanandle and the floor of the - Army Air Corps J?ljmg School in October 1(%33. cockpit. Since this handle could have been After two and a halt‘ years of service as an Army raised as a result M cable tension from impact, pilot, he started flying for United Air Llnes. its position cannot be regarded as indicative of From February 1940 to the date of this accideAit, the ptlock being either on or off during the he flew a captain for United, except for the as course of the take-d’f roll. period of May 18, lt&, to June 1916, when U, lhe airplane was equipped a Sperry A-32 on active duty with the A~JAir Forces. Of his with electric autanatic pilot. It is possible for a total of 8,703 f1)hlle: hours,’ 336 were in c-54 pilot to overpower this equipent when it is ty-pe equipnent. Instruction in the C-.% con- turned on, ani to methe airplane controls sisted of pmd sdrool &vi 10 hours Of flight through their fbll travel. The examination of training, a course offered to company pilots at all parts of the aukmatic pilot in Flight ,521 United’s San I”rancisc0 Flying School. After disclosed no evidence of malfunction, and all canpleting: the course in November 1‘346, Captain switches controls were found in the Balchvin was considered qualified bq the company and “off” position. to fly pilot on remlarly scheduled in as runs Two cylinders frm each engine were removed. C-<% airplanes. He was also certiftcated by the These cylinders and the interior of the power Civil Aeronautics Admlnistration for a 1,050 to sections were then mamined along with the mag- 10,800 horsepower rating. netic oil sunp plugs9 oil strainers, induction Robert Sands, age 28, holder of comoercial systems, and prop gwernors. As a result of pilot certificate No. 3n8;(cK), was the first of- this inspectlon, and of the Investigation to ficer for the flight. IIe was also trained in this date, no indication of any inechanical mal- the U. S. Amy Air Forces, and spent four )ears function has. been %mi in ar~of the power active duty with the air forces a military an as plants. pilot. He was employed bq United September 7, Sic!w, bends aria abrasions on propeller 1%5, as a stuient pilot; arvi was assipped as a tmifkmn to first officer December 4, l(A5. Robert Sands blades showed dmqe all four pro- accomplished C-W traininq for first officers at pellers. These markings indicated that the the United’s San Francisco Ply- School, Novem- lM, was qualified by the company to ‘The gust lock in the C-54 1s a mechanlsm which, ber and when locked. holds ?&e allerons. elevators, and the serve as a first offlcer in C-.% equipnent on in the neutw ~osltlon. The controls are v regularly scheduled runs. Mr. Sands had a total locked when the coneal handle is in the mupa posl- tlon, and unlocked u($en It Is Vowna. Sand begs are of 2,323 flyiris hours, 2.56 of whjch were in C-54 on occaslons carrleP ti alrcraft to obtain favorable tYPe equipnent. balance. Accident 1 nvest i gat ion Report 3- propellers were turnirg at a fairly high speed, witnesses %i&Xfied conce& the direction of but that little more than idle power was being smoke tnweti from the burning wreckage. This developed at the time the damage occurred. evidence sonflicting, end not reliable since Both wings were crushed by impact and par- the time d'&emation could not be definitely tially conssLwed by fire. The , however, determined in relation to the time of the acci- were found intact. There was no indication of dent. T& sxibject will be given Wther con- structural failure or mechanical malfunction. sideration Eater in the mport . !he abutxbnce of weather reporting stations An examh&lon of the gust lock control In in the New York area facilitated an accurate several ofQJMrted'sC-54s disclosed that the determination of weather conditions. On the mechanism hd been modified to allow the locking date of the accident a cold front extending from handle located to the imnediate right of the pi- Qitario, Canada, southward through Ohio, Ken- lot's seat to*mtuain in the up or "onn position tucb and Tennessee was moving 30 to 35 miles an without bekg held by either the gust lock warn- hour to the east. ing tape w by a locking pin attached to the . Approximately 200 miles in advance a prefrontal tape. Very sQ&t pressure on 'the handle would squall line had developed which was accompanied release the lock; however, if no tape was strung by thunderstorms, rain and hail. At 1630 the frau the reel at the top of the cockpit to the squall line had moved to a position 40 miles locking Me,no visual warning would be given northwest of Albany, New York, and thence to the pilot before take-off that the control through southeastern Pennsylvania. By 1730 both surfaces of the aircraft were actually locked. the U. S. Weather Bureau and United Air Lines Investigption also disclosed that the war- had made amendments to their previous forecast tape was used In two different ways. One mth& for LaGuardia, indicating that this squall line was to str- the tape through thie control would pass the LaGuardia terminal at 1930. wheel, wN& canstituted a very definite impedi- Weather observation stations located at. New- ment to the pilot in operating the aircraft, ark, New Jersey; Teterboro, New Jersey; Battery therefore, a pitive warning. The second meth- Place, New York City; Central Park, New York od was to place the tapelbehind and uriderneath City; the Administration Ruilding, LaGuardia, the trlm tab control, then directly to and Floyd Bennett and htitchell bields, New York, the gust lock handle. If the second method was noted the passage of the squall line by the used, the tape was forward and to the right of change in the direction of the wind. This the control wheel, and it was also far enough "windshiftfl occurred at Newark and Teterboro at removed flm the idle position of the throttles 1850 and at Central Park at 1859. as to offer no restriction to movement until In the Pan American Airways' weather oflice, throttles $ad been advanced to almost take-off located in the Marine Termirral Building on la- power setting, The second method had been e- ~uardiaField (700 feet west of Runway 18) no ployed in this case at the time that the air- official observations actually were made of the plane was perked in front of the terminal prior passage of the windshift. However, wind direc- to the loading of the passengers. tion and velocity were noted by the Pan American According to Douglas engineering &ta, the bfeteorologist. He stated that at the tjme of stalling speed of a C-54 loaded to 60,319 United's take-off (1905), the wind was from the pounds, (the grass weight of United's flight), southwest at 11 miles per hour. The U. SI per off, 15 degree flaps, is 93 miles per hour Weather Station in the IaCuardia Field Adminis- (see Douglas Report Shf-11840). The aircraft on tration Building, loca$ed approximately 3,100 , a level, hnrd surface runway*at sea level will feet east of Runway 18, recorded the passage of accelerate to that speed in a take-off roll of the windshift at 1909. This weather observation 1,550 feet. Mer no wind conditions, if the station made a preceding entry at 1902 for wind aircraft accelerates for take-off over a dts- Show- it to be south at 19 miles per hour. tance of 2,000 feet, the same engineer- data In addition to the above evidence obtained Micates that an air speed of 103 miles per fran weather reporting stations, considerable hour will be attained and if over a distance of testimony from other observers was introduced 2,500 feet, the air speed will increase-to 112 into the record. Two Pan American Airways' pi- miles per harr.3 lots present In the hlaritie Termlnal Building for Captain Baldwin stated that he saw 90 miles

t weather briefing observed Wtedls klight 521 on per hour on the air speed indlcator during his its tab-off roll. They stated that they noted the ~eadingSfor the wind direction and velocity bCrXtlcal engine failure speed for the C-54 (see in Pan American Airways' weather office at the Jouglas Derformance charts) loeded to 80,319 pounds, stfmdard atmos9herlc COndltlOnS. 1s 104 mlles per time that the aircraft was taking off. Accord- tlour. After the alrcrart attains thls speed, the dls- ing to them the wind was at that time south to tance to sum 1s equal to the distance to contlnue to I 50-raotbelght above the ground. three-engine oper southwest 15 to 233 miles per hour. Several lay rtlon. ._.. , . \ , , %- I , . I -+4 '.,I : -htdent Investigation Report ff roll. He also stated that it was his . Had the gra&mt been allowed for and the practice when taw off not to look at the air existing obst@ks taken into consideration, the I speed Indicator after he had attained an air gross allowable relght with a hcaifwind of u) speed of 90 miles per hour, but to then fly by miles per hour fm RunHay 18 would only have the "feel" of the airplane. In the present been 57,850 pouds. Or, for the actual weight case, according to Captain Baldwin, the "feel" of 60,319 pounuk, a runway of 3,893 feet utder of the controls was "heavy", and the aircraft the transport mitegory requirements would have did hot respond to the control pressures ap- been required. These requirements, in the in- plied. terests of safety, provide for a 50 foot clear- The Civil Aeronautics Administration's ap- ance at the eryP of the runway and of all obsta- proved "Airplane Operating blulual", prepared by cles in the tab-off path with a one engine the Douglas Aircraft Company, is required by failure at or sibr the critical speed.7 'Xhus, Civil Air Regulations to be carried in the air- assming rn erghe malr2nctianing and perform- plane. This manual contains, in addition to ance of the atnphne according to the criteria

lnf'omatiori concerning airplane operatian, cer- set fortT in tbe, Airplane *rating hfanual, the I

ta.in graphs f'ran which a pilot can determine airplane with fkel.1 power would have undoubtedly I minimmn talce-off Iynway length and critical en- cleared the & d a runway 3,893 feet long to- gine failure speed for any particular gross gether with th? existing obstacles with a mrgh weeight or wind condition. Since these graphs of mom than feet. are not suitable for quick and easy reference in Mter prolmged questioning in this investi- the airlJlam, United placed the information con- gation, it was discovered that the grcss .Heights cerning minirmm runway lengths in tabular form filed by the a%rlir~shiad never been checked by called "Gross Weight Charts". These are also any official ami that no standard calculations carried in the airplane and issued to the pi- have ever beenmriade against'whlch the weights lots. filed could easily be checked. There is no uni- Certain discrepancies exist between the data formity ~JIOWt& airlines with reference to the published by Douglas and the data prepared by allowable weights which thef file for identiql United. Reference to the "Airplane Operating planes. Xrxieed, these filings are not even made Manual" disclcses that a C54 loaded as was at one centra3 pint for the same airport. In- United's Elight 521, (f3,319pcmds) required stead they are made at the Civil Aermautics Ad- lader the transport category regulations, a run- ministration mional office that has jurisdic- way'3,m feet long (this is based on critical tion over the pticular carrier-for exanple, engine failure) if there is a headwind of 20 United's grass weights for operation out of La- miles per hour. Amway 18 at haGuardia is only Guardia are fX3ed in Chicago ani are not even 3,330 feet long. &themre, 'the graph does officially avaf8e;ble at the LaCuardia office of not irlclude my allowance for obstructions. the Civil AertmuCics Administration. Wted's Gross Weight Charts gave greater al- It is of iukrest to note also thtn when lowable weights for Runway 18. The weight al- Captain %ldwh chose Runway 18, he had before lowed for this particular ru~iway,accorciing to him tfie wemk rrmenifest which showed the actual those charts, was 60,!j50 with a headwind of 20 weight he was 6rrying. But, he testified that miles per hour. he made no reference to the table of allowable At the time of the compilation of these gross weights when & decided to use the short Runway weight charts no allowance was made for the 18. Later he testified that he believed the al- gradient in the runway,6 nor for two obstmles lowable grass wight for Runway 18 with a wind then in existence at the end of the runway. The of 21) miles per hour was sane 6n,O pounds. gradient of Runway 18 was ten.feet or approxi- The utilizaEion of winds to increase allowa- nrrtely 1 in 300 rising in the direction of take- ble ieights b a significant elemmt of the off. A United'States Coast atd Geodetic Survey transport categery fonnila. map of la[;uardia showing all obstacles and thir Each mlle-per-hour of wind, according to en- height had been published ad available for gineering cakulatims, permits an increase of about a year prior to the accident. United Mr 32n pounds. But, the formula allows only half Lines, however, had not acqured it until about of this wind eanponent to be utiiizea. Of bomonths prior to the accident. No correction course, the mgineering calculations rest upon had as yet been made for the obstacles referred the assumption that the wind is both steady and to above. directly on it%re nose of the plane. Unsteadiness I -.I -I . I c I 6kOrding to the testimony of the Unlted Air Llnes' englneers, a practice whose orlgln is somewhat 7 In the event of an englne failure at or before the Obscure, seems to have been prevalent in the industry crltlcal speed. the formula requires runway distance to disregard all gradlents in the calculation of al- sufficient to mermlt the airplane to be brought to a lowable gross weights unless they exceeded 1 in 200. StOD wlthln tnke-nrr nrnn Accident Investigation Report 6

of the wind is naturally not subject to ergi- of the fornula, that, if the enging are cut at neering calculatiom, but variatim in the di- the precise moment that the airplane reaches the rection of the wMcan be computed. If the di- critical speed, the airplane can be brought to a rection of the take-off is south and the wind is fLill stop at the precise point whm the take- southwest, the lifting capacity of a 20 mile per off area ends. hour southwest wind is only the equivalent of a 14 mile per hour south wM. Oiscussion The fonnila contained in the transport cate- The first.assumption Lndulged in as the prob- gory regulations at the time of the accident able cause of this accident was that the air- m account of the effect of temperature. took plane failed to clear 'he end of the runway be- All weights are calculated on of the basis cause of a sudden windshift occurring during .the temperature, 59' Fhhrenheit. A one de- standard midst of it6 We-off roll. Considering the gree rlse in temperature in the case of a C-54 closeness of the actual weight of the airplane has the effect of increasing the gross weght to its allowable weight, under the existing con- approximately lpC, y.r&.. In tile present case ditions, the significance of wind as an element the temperature was 67O, and in effect the gross in lncreasieg lift, and the known gustiness of weight was increased 9Cfi pounds. A tah-off the winds a& the time of take-off, such a hy- wder extreme conditiors with a temperature of pothesis sdhighly plausible. Under the 99' would mean that the gross weight had been transport category fo-a requirements a wind increased approximately 7,200 pounds or, to put shift could precipitate a crash. But, the evi- it another way, 36 unseen passengers estimated dence as mcpe Pdiy developed leaves this hy- at 200 pounds with their baggage have boarded pothesis ArQ$11y suslmt. The wind shift accord- plane. the ing to the tower did r:st occur until four rnirl- Another factor to note is that automatic wind Utes after ithe accident. Actmnittedlj the tower recorders seldom steady conditions with show was some 3+1M feet to east of the runway In reference to either direction or velocity. In question. 2kk observers in the an mrican me- case, direction fluctuating between this the was teorologiczil station, some 70feet to west of south and southwest, and the velocity vaxied as the rurnvaydso testified that no nud snift harl mch as 10 miles hour in short of per a period occurredaa the time they observed the aiP2lane fluctuations. Thus, it will be seen that not on its tahre-off roll. rhe runway thu is prac- only was the wMvariable at the observing tically bmcheted agahst the wind shift theory. point, but it was not necessarily sjnultaney Bloreiver, UM very f~llmeteorological evidence with the variations at the end of Ihniway 18, supports W absence of any wlrd shift. about two-thirds of a mile away; however, the general pattern of change at the two points was But, ts, the lay mid, the very fact that a essentially the same. wind shlflt of the character referred to herein Again, the thrust develop?d by the power might prmhce a tragic accident such as this Is plant of an airplane my.not always be that set a matter & genuine concern. Certainly, the forth in the ergineerhg miuals. heither mi- safety ofa&r transportation, If It Is to retain fold pressure nor tachometer readings are corn an increslhgly wide public confidence, cannot pletely accurate gauges of power.8 Also nich be allow& to let the safety of passengers hinge upon occumences of that character. The pilot 011 propeller blades, dents on wirgs or stabili- zers may considerably reduce lift requiring is chargd with the laiowledge of the interrela- lower distarlces in order to get an airplane tionship @aT wind direction and velocity, gross airborne. weight of aircraft, and runway length required. The tramport category formla contains safe- A pilot b certainly to be criticised if his re- quired lqthof take-off run is deperutent t~wn ty margins that are designed to campensate for ' these and other factors, such as normal varia- a given &xi velocity, and he endeavors a tal+ ttorls in tls proficiency of a pilot. Chief of off m~neup&rin the face of an uncertain wM these is th one-engine-out 50 foot clearance conNtim fmrolving an inminent wind shift. requirement. (he engine of the airplane is as- SLach a eaclition existed at the tlii that Cap- sumed to fail at the so-called critical speed. tain Baldkin started his tak-off. Nevertheless, the airplane aut be able to take- AgainF it may be thoqht tkat the plane was off and clear the end of the runway by 50 feet overload& and hence ffi-lled to take off. Tt 3s with the undercarriage still unretracted and the true that the plane was overloaded according to nropeller of the failed engine wlndmilllng and the correct calculations for this nmawaj ttwiva- Weathered. It is @so ass4for the purpose ble frm the approved operating mual for this type of plane with due reference to gradients is tu be noted that some or the latest type 1 airplanes have installed torque meters, which give a- and obstacles present on Runway 18. Accordirg direct lndlcatlon of Doaer. to the testimony of the engineers ant other ex- 4 -17428 6 Accident Jnvestioation Report .

per?, an airplane loaded to this weight, de- per hour. At such a speed it could easily have spite the fact that the legal requirements were ?xen.pulled aloft; certainly its nme-wheel -not met, should have taken off withcut diffl- should have left the grrxnad. But the nose-wheel culty i'rm this runway provided that the air- did not leave the ground, according to the tes- plane was functlonlng normally. And there is timoliy of all the cbservers including that of not the slightest proof, except me mtter later Captain Baklwin. to be mentioned, at the airplane was not func- True, the recollection of Captain Baldwin as tioning in a nom fashion. Nevertheless, thi? to the gust lock not be- released is to the airplane should not have been loaded to this contrary. But, uder the circmtances, recol- weight for this *runway. The fact that It was so lecticm of that character are by their very / loaded can be attributed to the miscalculatim nature frequently treacherous. he carm0;l story of wted, the lack of any excercise of super- of mislaM articles Is sufficiently eloquent to vision aver the filed weights by the Civil Aero- remind that many hstand well-intentioned nautics Administration, and the failure of Cap- people re-er having dorre things that they taln Baldwln even to refer to his chart of oper- never did. at% welghts prior to take-off on this runway. Assuning this hypothesis Is the correct one, lkro other pcssibilities remain. The first is what, one my well ask, does it prove? Thou- the employment of improper pilot technique by sarvfs of people daily attempt to start their CaptalriBaldwin. For reasons unknown, he my autanobiles with the emergency brake on. Eher- have becane unduly alarmed by the surlden ap gency brakes and gust lock are necessities. proach of the end of the runway, and my have ??ley cruxlot and shaild not be legislated out of wrorgly decided to cut power instead of pushing existence. Fortunately, the consequences of the throttles forward for the reserve power that 1eaviDg an emergency brake on are not serious; would have mde for clearance. Wlt this theory unfortunately, leavihg a gust lock on may not is only a surmise, and is inconsistent with the mybe serious, but traglc. A better device attitude of the .airplane dblng the case of than those that now exist of assuring that the the entire take-off roll, gust lock on these airplanes is released prior A more prhable hypothesis is that the ppt to the take-off roll is demanded. lock had not been released. Several factors in- cline towards this conclrrsicn. Due to the guSty, Findings *character of the'wirrls the gust lock was on when Lpan the basis of all available evidence, the the ship was being taxied to Its holding point Baard finds that: just off Runway 18. Due to the delay, occasioned 1. "he aircraft, crew, and carrier were prO- partly by the difficulty In Securing an appro- perly certificated. priate clearame from Airways h.affic Control, 2. No evidence has been fornd which Indicate& the gust lock may well have been left on or re- that there was aru. mechanical failure or mal- applied after the pre-take-off check with the function of the aircraft or any of its carp- Intent that it should be imnediately released mts. upan starting the tah-o~roll. That roll, it 3. Hrind was reporfedby the tower imnedjately will remenbered, was hurried. Furthermore, be prior to the time of take-off to be south, vari- the locking handle, as stated above, would re- able to southwest, 20 to 22 mils per harr, min in the Ifup" locked position without the or 4. Runway 18 at IaGuardia, 3,530 feet long, use of the gust lock Captain Baldwin tape, and has a gradient of 1 to 300, and has obstructions may have assullEd that the was off simply lock 32 feet high within 150 feet frm the south end. because the tape was reeled in and not strung to 5. United's Flight 521 loaded to a grass handle. the weight of 60,319 potmb required a runway 3,600 In further support of this theory the atti- feet long under 20 miles per hour headwind cow tule of the airplane during the talte-of'f roll is dltim, based on critical engh failure, ac- to be noted. It was sae 2,500 febt down the cor- to the Civil Aeronautics Administration rimway before the perwas cut by the co-pilot ApPrmd Birplane Operating Manual. Under the at the order of Captain Ekddwln.9 At that same conditions, Lhited's Grass Weight Chart point, even If no win3 conditlom prevailed, the shows Runway 18 at LaGuardia to be mable tbeh. airplam should have tyin a speed of 112 tnJles Only 3,530 feet lvrg with cbstructlons a feet high existing Lx) feet fran the south enti of 9There can be no question that the power WBS actu- that runway. ally off at the tlme the airplane crossed Qrand Cen- tral parkway. A TWA pilot at that partlcular moment 6. The alrplane accelerated nomdly for a happened to be drlvlng In his car on the DarkWaY re- distance approximately to porting to work. The airplane dented the top or hls of 2,000 feet an air car with Its undercarriage. This pilot testlrled speed in excess of 90 miles per hour after which that the airplane had its flaps down and made no the pilot applied brakes ordered the CO- . nolse. The happenstance or such concluslve testimony cud is most unusual. pilot to cut thk? engines. -17428 kcldent Investfgation Report \ 7. Durm the course of the takedff roll on ;r;reCt% -e laadS, and has foAated a €8mway 18, the airplane at all times maintained more permrracnt but still interim regulation per- a level attitude, ard the pilot experienced dif- mitting the adjustment of allowable loads to ficulty in actuating the controls. charges in temperature on a pore scientiflc 8. After the application of brakes the air- basis. * CRIft skidded for a distance of 800 feet to the 3. lpls Civil Ae~~naUtiCgBoard and the Civil end of Runway 18, 900 feet beyond before Aeronautics Administration have instructed their can,@ to rest. It was then alnast imnediately respective staffs to study the transport cate- . ernreloped in flames. gory requbmmts for tah-off and landing both 9. Of' the 48 occupents 43 were killed, 4 with regard to the formlation of a United . seriody injured anti one, th pilot, only States *tion on these matters for the pur: slightly injured. poses of international sWxiardIzation under the awipiees of the international Civil Aviation Probable Cause Organizetiori and with regard to increased safety The Board determines that the probable cawe in American domestic and international require- of this accident was the inability of the pilot ments. Thjs will take the. to actuate the controls due to the gust lock be- 4. Ihe 4Xvil Aeronautics Administration in ing on, resulting in the pilot's decision to cooperatian with the airlines will work out uni- discontinue the take-off at a point too far down form weight 1Mtations for all runways used by the runway to permit stoppirg within the airport the certificated comnercial airlines in the . bcurm3aries . United States on the basis of the revised inter- - BY TME CIVIL AERONAUTICS BOARD: im fonmtlas. Is/ J. 1. LAMlIS 5. The Civil Aeronautics Admlnlstration has deflned pramilgated a definition of winds so f Is/ OSWALD RYAN and Is/ MLUE BRANCH as to limit the use of'winds in the transport Is/ JOSE LEE category requirements to those that are reason- . /sf CLARENCE X. YOUVG ably steady and constaht. 6. The Civil Aeronautics Administration and the Air 'Ramport Association have taken steps to Indoctrinate pilots speciflcally in the mean- ing and use of the trarsport category formilas so as to ftdly acquaint them with the margins of safety cartained. Corrective Action 7. ThePresideent's Special Board has request This accident has not only been of concern to ed the mmfkcturers of this airplane to rede- the Civil Aeronautics Board but also to the sign several aspects of the gust lock, so as .to President's Special Board of Inquiry on Air providt? against its locldng during take-off or Safety. A close liaison between the two as well flight ard so as to provide more adequate warn- as the Civil Aercnautics Administration has been ing again& it being locked at the time of take- maintained. The corrective action that has been off. atre aesign feature has already been ccm- taken thus stam fran all three bodies as well pleted Md is being installed. as the municipal airport authority. 8. The President's Special Board has recorn- 1. The Civil Aeronautics Board has amended menled the installation of lighted wind socks at the Civil Air Regulations so as to eliminate the emis of all runways utilized by certificated the word "appreciable" as itnapplies to runway ccmnercial aircraft. Fdlure of the mmlcipal- gradients. The result is that all gradients ities to respond to this suggestion may call for mrst be included in calculating allowable weight fbrther action. limitations on all runways. 9. The municipal authorities of New York City 2. The Civil Aeronautics Board has prarml- have closed Runway 18 to all four engine air- gated an emergency remation providing for an craft. arbitrary reduction In allowable weight llmita- In short, all action that it seem reasonablp tions that will take account of temperature as and necessary to take has already been taken. -17428

... I . . .' .. ! ,. 1 .>>e . -

\ .-A Supplemental Data

rrlr. :- Investigation and Hearing _I 1. '&)&.rting cpm this 'flight. His last physical ex- ccmpany %, - Notification of this accident was given by aminationwas given by the January at'&d!eh-tiroe was foul mysically eye witnesses to the Chief of Region I for the 1947, he . Civil Aeronautics Board, and Investigation was . qualified Um fly. His last Civil Aeronautics AdminiStr&im physical examination was given irmEdiately initiated in accordance with the . provisions of Section 702 (a) (2) of the Civil J~nuary20, XM7. RoberfE age holder of Cmrcial Aerqutics Act of 1938, RS amded. On June SW, 28, 11, 1947, a @lit hearing was held in New York Pilot Cer$W%eate No. 3083#, had a total of 256 of khlch were in C54 City, New York. I. 2,323 flm hours, equipment, ming the month preceding tNs A!; Carrier flight, he flew a total of 79 hours and was given a nest pried of 41 hours preceding the United Air Lines, Inc., was incorporated departure Uirrae for this flight. Last company der the laws of the State of Delaware on June physical emadnation waS given April 3, 1947, at 20, 1934. The comppny is the holder of a cer- which timeh? was fowl qualified for flight. tificate of public convenience ad necessity for His last WiB Aeronautics Administration physi- Route 1 issued by the Civil Aeronautics Board. cal examhallian was Septenber 14, 19% TNS route, from LaGuardia to Clevelard, WRS the . 8, - one over which Uted's 522 was scheduled to The Aircraft LI . fly* NC 30@W9 United's Flight 521, was a C-52B-M: FI i ght Personne I airplane RBwEn'ractured by the Doqlas Aircraft Comp%ny%m~h17, 1944. The aircraft was pur- Captain Elenton R. Baldwin, age 38, held Air chased by Uhlted from the War Assets Corpora- Transport Certificate No. 293879 with a multi- tion, an8m converted to Civil Aeronautics , ergine 1G60-10,800 horsepower rat%. He hRd a Administsaation ard unit& Air Lines requirements total of 8,703 fly% hours, 336 of which were by Dowllaa; Aircraft Comptuur, April 6,-1W. It in C4X type equipment. During the month pre- had a total of 5,950 flying hours. The last No. ceding thfs accident, Captain Raldwin flew 84 .3 check- acccmplished \fay 26, 1946, ~nithe hours ad had a rest period of 5 days before last No. 3 check accomplished hfay 26, 1W7. ENGINES No. 1 [email protected] Nunber...... P-l@Zi'tX Date of last overhaul.....,...... ,... 3-2647 Time accumilated during previous run...... 546: 13 (nom1 removal for overhaul) Time since overhaul at thof accident...... -..,. 483:08 Total time at last overhaul...... ,... 243%:31 . Total time at time of accident...... B17:39 . No. 2 Ekgine-Serial NWer...... ,... P-1- Date of last overhaul...... 3-1347 Time accurmlated durirg previous run...... 726:27 (nom1 change acct. tb) Time since overhaul at time of accident...... 483:08 Total time at last overhaul...... 3396:42 Total ti& at time of accident ...... 38'79:50 No-. 3 Bgine--Serial mer...... -... P-1033j2 Date of last overhaul...... 3-41-47 Time accdated during prevlous run..: ...... 410:Ol (nom1 change acct. time) -Time since averhaul at time of accident ...... 483:08 Total tine at last over^^...... ).... &%3111:00 Total time at time of accid~nt...... ,...... ;?891:08 No. 4 Ergine-Serlal Mer...... p-105a Date of last overhaul...... 4447 Time accdated durirlg previous rur~...... ~... 376:23 (removed wct. failure at=') The since overhaul at tinre of accident ...... W:O8 Total tine at last overhaul...... 3&1:23 Total time at time of accident ...... 3774:31

a (1) -17428 -- .Supplemental Data (Confinued)

At Time of kccldent Total time NO. l-No. 300183 -Hub No. RRA m66...... 14??: 17 5054: 16 . Bladee NO. RRE 4X@...... ' E1m17 5054:16 RRE4940 ...... 1477: 17 5Ow: 16

c RFIE 4941 ...... 1477:17 5084: 16 + NO. %NO. 3001143 Mt, No. RRD 1155 ...... 483:cm 474:09 I Blades No. 1480...... :09 I RRN 4g3:m 4974 m 1481...... 483:08 a74: 09 RRN 1482.e...... 483:- 4974:w No. 3-No. 3001136 MJ, No. RRC 7321 ...... a:* 5337:m Blades No. RRL 2351 ...... Q81:ob 5337:52 m 2352...... 481:06 5337:m m 2.353 ...... 481:- a37:32 NO. 4-NO. 300156 Hub No. RRB Zi€B...... 4m:m 6522:31 Blades No. RRU 81% 14m 15 1477: 15. RRU 8156.'...... 14R:Is 1477:15 RRU 8l57...... 1477:a 1477: 1s I -17428