FOR ABOUT A week last year in October, just as the Dahiya household in Delhi was beginning to prepare for Diwali, the family would wake up in the morning to find the terrace and the outer walls of their home spattered with a mysterious substance emitting a foul and bitter odour. Something similar had occurred in October 2015. Back then, it was an isolated incident, so the Dahiyas, without giving it much thought, got the house cleaned and whitewashed. This time, however, the slathering repeated itself for six or seven nights in a row. They soon found out that their neighbours too were suffering the same. “It was shit,” says a member of the family, under the condition of anonymity as the matter is now in court. “And it was dropping from the sky.”
The Dahiyas live in Vasant Vihar, Delhi, a locality close to the Indira Gandhi International Airport. They believe that human excreta has been leaking from aircraft toilets as flights take off. The head of the house, Satwant Singh Dahiya, a retired lieutenant general of the Indian Army, filed a petition at the National Green Tribunal. The Central Pollution Control Board, which was tasked by the environment court to collect and analyse samples from the walls, confirmed their suspicion. It was indeed human excreta, although the board claimed it could not ascertain its source. And in December, while adjudicating on the case, the court ruled that the Directorate General of Civil Aviation (DGCA) must issue directives so that aircraft, upon landing, are subjected to surprise inspections to see if their waste storage tanks are empty. If they are found empty, the tribunal ordered, a fine of Rs 50,000 would be levied.
According to Bimal Kumar Srivastava, an aviation consultant who previously worked with the Airport Authority of India, the leakage of waste material from aircraft onto earth is an incredibly rare phenomenon across the world, although its frequency in India appears to be on the increase. Srivastava has been studying such cases for the past few years. He records these cases, ascertains air traffic routes over reported drop sites, and measures their proximity to the airport. He has been publishing his findings in aviation journals and websites, apart from sometimes reporting confirmed incidents to the DGCA. He has so far found 66 cases of waste falling from aircraft in India, the earliest case being in 2004. “It could be that there are more cases in India now because of more air travel and more airports. Or it could simply be that people are reporting it more now,” Srivastava says.
In commercial aircraft, lavatory waste is stored in a tank. A chemical, usually blue in colour, is mixed with water inside this tank to deodorise the waste and break down solids. Once the aircraft lands, the waste is dispelled. Seepage from toilet drain lines can occur and some lavatory fluid can escape. “The low temperature outside the flying aircraft then condenses such liquid into ice,” Srivastava explains. When the ice becomes too heavy, it falls to the ground. This normally occurs, he adds, during an aircraft’s descent, when, moving from a higher to lower altitude, the aircraft experiences higher atmospheric temperature. In his reports, Srivastava notes that most ‘blue ice fall’ cases tend to occur in parts of Gujarat and Rajasthan over which aircraft headed for the airports of Mumbai and Delhi begin their descent.
The falling ‘ice’ can be small enough to fit into your palm or large enough to rip through roofs and create holes in the ground. In 2015, Srivastava learnt of a case where a 60-year-old woman in Madhya Pradesh’s Aamkhoh village was hospitalised for several days after a large chunk of blue ice fell from an aeroplane, crashed through her roof, and injured her. Once the ice starts melting, it gives off a foul odour.
“Often people don’t realise it has fallen from an aircraft. So they think it must have dropped from a satellite. Or it must be something divine,” Srivastava says. “Sometimes people collect it and apply it on their faces and bodies [thinking it is good for their skin]. There have even been cases where people have eaten it.”
The National Green Tribunal’s order, directing the DGCA to issue directives where surprise checks will be conducted on aircraft’s waste storage tanks, is perhaps the best solution so far, believes Srivastava. “I got into studying this phenomenon because it is an incredibly under-reported issue. And it can be very dangerous,” he says. Victims, according to Srivastava, must be entitled to compensation under the Aircraft (Investigation of Accidents and Incidents) Rules, 2012, although so far there have been no cases where people have claimed it.
The Dahiya household’s case, however, is peculiar in its nature. They have found excreta splattered on their house but never any evidence of ice. “Also the strange thing is aircraft cover several kilometres in a single minute. So it seems very odd for it to occur again and again in a single locality,” Srivastava says.
The Dahiyas, though, are certain. Three months have passed since the last incident and their last clean-up. Investigators have visited twice to collect and analyse samples. “People keep saying it cannot be from an aircraft,” says a member of the family. “Only we know how rotten all this is.”