It was February over the Alps in central Europe and my colleague and I had stopped off in Strasbourg to re-fuel our single engine piston aircraft before continuing on to Ljubljana in Slovenia. We had stayed above the clouds on the way down but my stomach was tight knowing we had to descend through the cloud.
Apart from a small amount of ice building on the front of the aircraft the arrival was uneventful, but on departure the cloud levels had risen and we spent a lot longer in cloud than I was comfortable with! Looking back, it was silly to take off in the first place (I was young in those days!), in an aircraft without any de-icing systems on the wings. Fortunately we did eventually clear the clouds, but only after a significant amount of ice had formed on the wings, the window, the nose cone … almost everywhere in fact. All you can do in this situation is pray you get lucky, get out of the icing environment, and hope the ice falls off eventually.
Even later in life, flying an aircraft with full de-icing systems, you can never be too careful; flight in icing conditions always requires a great deal of respect from a pilot.
A while ago I was flying from Jersey in the Channel Islands to Leeds in my small twin engine aircraft. It was the middle of winter, and the flight was delayed leaving the Channel Islands due to snow. The problem was further compounded as airports all over England were closing due to high levels of snowfall. Before I left Jersey I phoned a senior pilot in my company and had a good long discussion about my alternates (other landing strips) if Leeds closed. I had an hour’s window either side of my arrival time where I had one airport I could divert to if necessary, before virtually everywhere else was engulfed in snow and closed.
I took off on the 1 1/2 hour flight from Jersey. The first hour was fine as I was above the cloud and therefore above any serious ice. As I approached Leeds I was under radar control; unfortunately any plane has to come down through the cloud to land eventually! Taken lower and lower into the cloud a glance over my shoulder at the wings showed the ice building, and building quickly. I inflate the boots and the ice falls off, but within seconds it returns. Usually you wait for 1/4inch thickness before activating the boots to ensure that the ice breaks off, and doesn’t just expand over the boot. On this night though I was inflating them every 30 seconds to try and keep the wings clear.
Air Traffic Control (ATC) then spoke to me over the radio, “XXX, we are going to have to hold you for 10 minutes as we have high speed jet traffic we need to place in front of you”.
The only response in this situation is to tell the truth. “Leeds radar, I cannot do that, I’m building up too much ice and need to land quickly”.
ATC in England are very good, but they cannot know what is happening to you, and when times are tough, there is no question of ‘being brave’, you tell them exactly what is happening to you, and you get the aircraft on the ground quickly!
“XXX Roger, you are number one for the approach”.
Within 5 mins. of landing in Leeds the airport closed due to snow and the jet traffic behind me had to divert in the end, so I had definitely made the right decision! As my aircraft was being put into a hangar for the night I inspected the outside. Every part that didn’t have de-icing systems had several inches of thick ice stuck on it.
Flying is not dangerous, but as a pilot it is your responsibility to ensure that your aircraft is safe at all times. It is easy to become too focused on one aspect of the aircraft’s flight, and forget to look over your shoulder at the wing when in icing conditions; remembering to do this is called situational awareness: the cornerstone of a good aviator.
In flight icing is one of the most common weather phenomena that pilots can face on a daily basis. It is capable of bringing down an aircraft, large or small, if not noticed quickly, and dealt with efficiently. Icing only forms on aircraft when in visible moisture (ie, cloud!), generally when the temperature is below 0 degrees Celsius.
Ice on the wings is removed in two main ways. Smaller aircraft, from light twins to regional turbo-props, have rubber matting on the front of the wing, called “boots”; once the ice has built up sufficiently these “boots” inflate and theoretically break off any ice that has accumulated. The other method used in larger aircraft is funnelling excess heat from the engine to the whole leading edge of the wing, thus preventing any ice from forming in the first place.