The definition of blue ice on an aircraft has nothing to do with fancy drinks or cocktails. In fact, it's quite the opposite.

According to SKYbrary, ‘blue ice’ is known as “the frozen sewage material that has leaked mid-flight from commercial aircraft lavatory waste systems.”

In simpler words, it’s frozen waste from the lavatories, a mixture of human waste and blue disinfectant, which freezes at temperatures below 60C.

The ‘blue ice’ that has been accumulated throughout the flight can then detach from the aircraft during the landing. Although it’s rare to fall from its high altitude, it could be dangerous to anyone it falls on, and could even damage a property.

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Airlines are not actually allowed to deliberately dispose of such waste mid-flight and, according to Skybrary, they have no means of doing so.

There is no special lever to pull. But there have been occasions where leaks have happened from the septic tank on-board an aircraft.

Heathrow Airport, Britain's biggest aviation hub, says there are on average 25 ice fall incidents per year countrywide. "So the chance of experiencing property damage due to falling ice is extremely low," it added.

It then went on to explain exactly how the waste is collected, and said: "Waste collection happens when the aircraft lands at an airport and is disposed of responsibly. However, there have been reported incidents where the hose valve that is used to empty the aircraft has been faulty and leaked fluid which has frozen at altitude.

"This rare occurrence usually results in discoloured ice and is commonly referred to as “blue ice.”

As reported by the Daily Mail in December 2015, a woman in her 60s got almost hit with a chunk of a mysterious block of ice that fell from the sky over a village in India.

The woman was left with a shoulder injury. However, she said that those from her village, Aamkhoh, could’ve received worse injuries. Witnesses said the ice crashed onto someone’s home terrace before it got to her.

In 2016, a teacher from Canada claimed that a “frozen lump of excrement from a plane passing overhead” created a hole in the roof of her mother’s home.

She claimed that right after waking up from a loud noise, she found a hole in the ceiling with a puddle of water on the floor, 15 feet from where she was sleeping.

After calling a professional to inspect and repair the damage, they described it to be the “strangest thing they had ever seen.”

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