Ask the Captain: How do pilots handle rain and snow?

— -- Question: Hello Capt. Cox, I live in Colorado. During winter. I have seen frost on the wings prior to takeoff. I have wanted to ask if we will be de-icing, but I never have. I have a fear because we had a crash in a nearby regional airport some years ago, where the pilot opted not to de-ice, and they crashed upon takeoff. How much frost is okay?

— submitted by reader karatechick

Answer: Even slight amounts of frost can disrupt the airflow on a wing. The FAA requires a clean wing before flight. This means that there is no contaminate adhering to the wing.

There have been a few accidents when ice was on the wing when takeoff was attempted. Some airplanes are more susceptible to ground icing, which frost is considered, than others.

One other consideration: In some places, I have heard of a special procedure where the frost could be polished to prevent airflow disruption. I do not know if it is still used anywhere.

Q: When a jet flies through a heavy rain storm/squall, what prevents all of the water that is being injested from shutting down the engine?

— davefl305

A: Jet engines can inject large amount of water without flaming out. In today's modern fan-jet engines, most of the water is spun out the fan duct and does not pass through the core of the engine. In the core of the engine, air has been heated by the compression process and much of the water is steam, which passes through the combustor and out the exhaust. Pilots will also have the ignition system on during flight through precipitation just in case there is a momentary flame out.

Q: My thoughts drifted back to my flight home from ORD (Chicago O'Hare) to IAH (Houston Intercontinental) during Tropical Storm Allison. As we were touching down, landing was aborted when the control tower blacked out. Watching the rain pelting us, my thoughts were about the engines. Just how much water can those puppies suck in before they start to foul out?

— Jim.Davis

A: Modern turbine engines are carefully tested and certified to ensure that water ingestion will not cause a problem. In the 1980s one engine type had some cases of flaming out in very heavy rain. These engines were modified and the problem has not reoccurred.

My experience is that jet engines run well even when ingesting very heavy rain.

Readers, please leave your questions for John Cox here, and only leave comments about this week's column below.

John Cox is a retired airline captain with U.S. Airways and runs his own aviation safety consulting company, Safety Operating Systems.