Aviation myths debunked

Q: Conspiracy theorists claim that the exhaust from jets is chemtrails and chemicals being dumped on populations. Is there any truth to these theories? — Starling Johnson, Atlanta

A: No, there is no truth to the chemtrail claims. The moisture in the air when heated by a jet engine, then cooled, causes ice crystals we see as white contrails. The Internet is full of conspiracy theorists with various untrue claims; the chemtrail claim is one of them. Q: Is it true that a soda can or a bag of chips will pop in a plane at high altitude? — Kamal, N.J.

A: Not in normal circumstances. The cabin is pressurized to no more than 8,000 feet; therefore, a soda can or bag of chips is no more likely to rupture than if it were sent up to a town in the mountains above 8,000 feet. Q: Is it true that flight times are padded by about 20 minutes? — Phillip Demarest, Potsdam, N.Y.

A: No, there is not a blanket 20-minute padding. Airlines will look at the history of the flight time and the taxi time to publish the block time. Q: You’ve mentioned that a non-pilot would fail in being talked through a landing. A “Mythbusters” episode showed that it probably can be done. Also, Wikipedia documents two instances where it has been done.

— Paul, Austin A: I will look for the episode. My response is based on the complexity of the tasks to land an airliner.

On Wikipedia, I found no entries documenting an airliner landed by a non-pilot. There were two small airplane incidents, to which you refer. One was a pilot that had not flown that type of airplane previously. One was a true non-pilot. General aviation aircraft are significantly less complex than commercial jets.