When Blue Ice Falls from the Sky!
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BIMAL K. SRIVASTAVA WhenWhen What happens when a huge lump of BlueBlue IceIce coloured ice falls from a clear sky? Falls From Well, there are Falls From conjectures, often magical Feature Article Feature TheThe SkySky!! explanations. But the culprits are often commercial aircraft. Read on to find out more. This piece of blue ice is most likely from an aircraft flying over the International Air Route A791W Kolkata-Karachi on 6 October 1991 found near Mt Abu in Rajasthan (Photo Courtesy Prof. K.K. Sharma) Suddenly, a big blast was heard as if Of course this was highly improbable, as N 19 February 2011, at around a bomb had gone off. Every one ran the weather was clear, there were no 09.30 hrs in the morning, a chunk outside only to find a clear sky and no clouds, and no thunder was heard. Could Oof green-coloured ice dropped clouds, thereby ruling out the possibility of the ice have fallen off from some flying from the sky in the Central Reserve Police a thunderstorm or lightning strike. And then object such as an aeroplane? Well, that Force (CRPF) Camp at Suthyana, Greater they saw it! A huge block of blue coloured appeared most likely. Noida near Delhi. The area on the ground ice weighing at least 10 kg that had where the ice fell also became green in created a hole about half a feet in the colour. The piece of ice was collected ground. Fortunately, no one was injured and the matter was reported by CRPF nor any property damaged. Photo of ice that fell in Imphal on officials to the Police. Scientists are still The big crowd that gathered to watch 31 January 2010 probing the matter. The only clue was that the phenomenon was at a loss to figure the area lies at a distance of about 40 km out how such a huge block of ice could to the east of the Indira Gandhi have dropped down from the clear skies. International Airport in New Delhi and falls People took photographs from their in the approach path, where the aircraft mobile phones. Some wondered whether align themselves for landing. it was god’s curse. The ice block melted A similar incident occurred on 18 May after about two and a half hours. Many 2008 in a village of Haryana called Hajibas. people collected water samples from the Delhi and in its neighbouring state melting ice. And, as expected, the local Haryana are normally dry with no signs of Hindi newspaper reported the incident as the Monsoon during this period. The sky a mystic occurrence the next day. was clear and bright. The time was about Now, what could be the reason for 10:30 hrs in the morning. A marriage party such a bizarre event? Could the ice be a rested peacefully. collection of ice flakes or a bunch of hails? 19 SCIENCE REPORTER, JULY 2011 Feature Article This is how the aircraft toilets are cleaned after landing of aircraft (above); After landing, the ground servicing vehicles clear the toilet tanks by removing the contents for disposal; (above right) Aircraft toilets look like normal toilets though they work on the vacuum suction principle (inset). The Mystery water is the main carrier in home toilets All along the journey, the lavatory The most probable source of the blue ice carrying all the waste to the drains. waste is stored in a holding tank on the was indeed a commercial aircraft flying Unlike the toilets in household aircraft. After landing, the toilet cleaning high in the sky, and that too from the most bathrooms, toilets installed in modern carts are deployed by ground crew unexpected of places—from one of its commercial airliners work on the principle personnel who operate a valve to empty lavatories! of vacuum suction—active vacuum as the waste storage tank and make it ready Before getting deeper into the compared to passive siphons of household for the next part of the journey. It is physically mystery, let us see how the toilet system of toilets. Since the waste gets sucked out not possible for a pilot to dump a tank modern aeroplanes functions. In fact it is through vacuum suction, these aircraft while in flight. The exterior lever means only quite different than the toilet system toilets don’t rely on gravity and gush of the ground crew can operate the valve installed in our houses. water. that opens the tank while the plane is on The typical home toilet uses a tank When the aircraft toilet is flushed, it the ground. filled with water. When the toilet is flushed, opens a valve in the drain line, and the it starts a siphon that drains the contents. vacuum in the line sucks out the contents A chunk of ice that had fallen on the home of a US couple on 21 October 2006 (below); it damaged the bed The water then flows into the septic tank or into a tank. Use of vacuum requires very of the couple after crashing through the roof (bottom) in the drain system due to gravity. Thus, little water to clean the bowl (water may be replaced by the blue sanitizing liquid). Most vacuum systems flush with just two liters of fluid or less compared to six liters for a water-saving toilet and up to 20 liters for an older toilet. The use of vacuum system in aircraft offers two clear-cut benefits—reduced weight of the aircraft and saving of water (in fact this also indirectly results in reduction of weight of the aircraft). Because the vacuums are so powerful, the pipes can be made narrow and very little water is required for flushing. And since gravity is not involved, the drainpipes can be run straight up to the septic tanks to conserve space. They can also be made vertically up or down or in any other direction. Thus when a vacuum toilet is flushed, the solid waste and a The blue ice sample of 6 October 2009 after melting small amount of blue sanitizing liquid are turned into a blue liquid, like a sanitizing agent sucked into the tank. (Photo Courtesy Prof. K.K. Sharma) SCIENCE REPORTER, JULY 2011 20 Feature Article The United States Rare Case in India Now, how do we co-relate the above- alone has recorded mentioned incident in a village of Haryana at least 27 incidents in 2008 with that of blue ice from an aircraft? Well, the location of the incident of blue ice impacts was compared vis-à-vis the routes followed by aircraft and phases of flight. between 1970 and Village Hajibas is situated near 2003, some of Pinangwan (Latitude 27053’37"N, Longitude 77007’30"E.), which is located in District. which caused Gurgaon (Haryana) at a distance of about considerable 75 km (aerial distance) from the Indira Gandhi International (IGI) Airport, Delhi damage. exactly towards south (on a bearing of 1800). This place lies below the Air Traffic Normally a dark blue coloured Services (ATS) route known as W-20N Aircraft Involved (Bhopal-Delhi Sector) and when over this chemical (sanitizing liquid) is mixed with Only passenger airliners are involved in such cleaning water inside the aircraft lavatory place, the aircraft are approximately 15 incidents due to the fact that only these to 20 minutes from land at IGI airport. This holding tanks to deodorize the waste and aircraft are equipped with heavy-duty to break down any solids. The blue route is normally used by aircraft arriving passenger toilets that are regularly used from the South (Bhopal, Nagpur, chemical serves another purpose. In the by passengers on board the aircraft. event of any leakage from the drainpipes, Hyderabad, or Chennai) and the distance Thus a defence aircraft or a small civil matches with the area where commercial the ground engineers are able to detect aircraft would not be involved in such the leakage by observing the presence of airliners are descending from their cruising incidents. level of about 30,000 feet down to 15,000 blue colour on the exterior of the aircraft In other words, one of the primary and thus repair it. feet, where temperatures are conditions for occurrence of such cases comparatively higher than the cruising is that the place of incident must be level. How the Problem Starts located below an established air-route or Combining all these facts and figures, Modern commercial aircraft cruise at high it should be close to an airport where the incident definitely deserved to be altitudes, and the sub-zero temperatures passenger airliners are operating. categorized as one of the rarest cause any liquid to freeze immediately, Another condition is that the ice will phenomena of blue aircraft ice falling to hence the term “blue Ice.” If any of this get formed during flight only when there is the ground. The matter was also reported “blue Ice” were to fall from an aircraft, it some kind of leakage or seepage in the to the Director General of Civil Aviation, would melt long before it hit the ground, aircraft toilets. This ice will however fall on New Delhi. It is understood from DGCA that dissipating into miniscule droplets that are the ground only under two conditions: though there had been many incidents of nearly invisible. i) When the airliner is descending (may leakage of toilet drains, this was the first In the event of any abnormality or be for the purpose of landing) so that the reported fall of blue ice in India. defect, such as due to leakage or atmospheric temperature outside starts seepage, small amounts of lavatory fluid rising, and the ice starts melting and falls Another incident of fall of blue ice in leak outside and get condensed due to down and/or; India was reported near Mount Abu in the low outside temperature.