Plane Answers: Frost on the wings and non-flying pilot duties

Welcome to Gadling’s feature, Plane Answers, where our resident airline pilot, Kent Wien, answers your questions about everything from takeoff to touchdown and beyond. Have a question of your own? Ask away!

Paul asks:

Can a plane take off with frost on it or does it have to be de-iced ?

In the U.S., the FAA’s Federal Aviation Regulation 121.629 (c) says:

(b) No person may take off an aircraft when frost, ice, or snow is
adhering to the wings, control surfaces, propellers, engine inlets, or
other critical surfaces of the aircraft. Takeoffs with frost
under the wing in the area of the fuel tanks may be authorized by the

While there may be cases where some frost is allowed on the fuselage or even the bottom side of a wing, any frost, snow or ice on the wings and tail must be de-iced before takeoff.

De-icing technology has advanced significantly in the past 20 years with the increased use of newer anti-ice fluids. Previously we would de-ice with what’s called ‘type-1’ fluid, which removed the ice and snow from an airplane, but didn’t protect the wing from any further snow accumulation.

After de-icing, we have what’s called a holdover time. If we weren’t off the ground within the time specified in the holdover charts, we would have to have the wing inspected to ensure that snow isn’t accumulating or we’d have to be de-iced again. It wasn’t uncommon for a flight to make a couple of unsuccessful attempts at taxiing for takeoff within the holdover time.

Today we use a two-step process when it’s snowing outside. We still de-ice with type-1 fluid, either at the gate or after we push back and then our de-ice crew will apply a type-IV fluid, which has anti-ice properties.

You may have seen a wing with the thick green fluid on top. As snow continues to fall, this fluid can prevent any accumulation on the wing for well over an hour, depending on the conditions. This is a huge improvement to the type-1 holdover times which were as short as 10 minutes.

Unfortunately this two-part process takes at least 30 minutes to complete, depending on the amount of snow on the wings. I’ve had it take well over an hour, in fact. And that doesn’t include waiting for the other airplanes to finish before the de-ice crew can start on our aircraft.

Airlines are incredibly conservative about de-icing. Because of some high profile accidents that occurred in the early ’80s, we understandably still get many concerned questions from nervous passengers about the process.


Tom asks:

Hey Kent,

In a lot of your Paris trip posts you mention “non-flying duties.” What are these non-flying duties? How long do some of these take and do you have any paperwork to fill out after a flight like a police officer does at the end of his day? Or do you just fly and land and once your trip is done go home?

I may have been talking about non-flying duties as they relate to a pilot who’s not the flying pilot on a particular flight. Since the captain and co-pilot swap ‘legs’ allowing one pilot to fly the trip over and the other to fly back, the pilot not flying handles most of the non-flying duties.

This mainly involves communicating with ATC, but it also includes bringing the landing gear and flaps up and down and a few specific tasks such as setting the target altitude and headings when the other pilot is hand-flying.

The non-flying pilot usually pulls up weather and types any messages to the company via the ACARS unit as well.

After we arrive at our home base, it’s just a matter of saying goodbye to the passengers and the rest of the crew, jumping on the employee bus and driving home.

One of the best parts of the job is the lack of homework, with one exception; we change out hundreds of pages in our Jeppesen approach plates and aircraft operating manuals between trips. These packaged updates take about twenty minutes each, and we tend to get four to eight a month.

I personally have the added non-flying duty of writing about some of the more interesting trips, and sharing photos and video with you, although I’ve been running a few weeks behind in these Cockpit Chronicles posts.

Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he’ll use it for next Monday’s Plane Answers