Ralf wrote:
We have winter in Ohio now and most of our runways are plowed but still do have compacted patchy snow on it.
Is there anybody on the list who can give me some advice on departing and landing a 4P on snow?
How much runway do I need if braking action is very small? Does it behave like normal or is it much different on snow? How do you hold it straight at the start when the rudder is not working yet?
Any input is appreciated.
Ralf,
I am by no means an authority, and I have only operated my IV-P on icy/snowy runways a few times, but can give
you some tips/considerations from flying small airplanes (and F-4’s) in Alaska for several years…
First of all, there are some bright sunny winter days that look good for flying that just are not suitable. Icy
or patchy runways/taxiways combined with strong winds and/or short runways are my best examples. The IV-P will “weather vane” with the best of small airplanes if all the wheels don’t have a good grip on the surface, and when it starts, abrupt controls to “regain
the straight and narrow” can make it much worse…very quickly.
So the first tip: GENTLE on the controls…all of them…starting with the brakes, and especially with the power
on takeoff. You should be able to easily advance the power to takeoff without touching the brakes. Takes just a bit more runway to get to full power with the slow throttle push, but with winter temps, your takeoff roll is probably shorter than summer anyway.
Again, crosswinds are more treacherous than when operating on a dry surface.
Your crosswind limits should be SIGNIFICANTLY reduced…and it’s not just a takeoff/landing consideration. Maneuvering the airplane on the ground can also be an issue. So there is also a rather low total wind that’s acceptable if the taxi/takeoff surfaces
are slippery/patchy. Another tip: Be prepared to shut down the engine (completely and quickly) with the magneto switch if you get into trouble during taxi.
In the F-4, we had very detailed stopping distance charts for various runway braking coefficients (which were
measured and broadcast by the tower), but neither are readily available for most GA operations. You can, however do some testing on your own before venturing out on the ice. Try landing and rolling out, using only aero braking, the next time you’re out flying
on dry runway, to see how much distance it will take. In my experience, the airplane won’t ever stop rolling on a hard surface without the brakes…unless you shut down the engine after landing. So give it a try, then try some very light braking after slowing
to 50 kts or less. This somewhat replicates the slight wheel drag that a small amount of snow will provide, and will give you some idea of runway required. 5,000’ is probably the minimum I’d even consider for an icy/patchy runway;
7,000’ should be sufficient if you land at the approach end (L
not all of our pilots do this!) with the speed at 1.2-1.3 stall--remembering that it varies with weight. Remember that the energy needed to stop is a function of the square of the touchdown velocity. Five knots makes a big difference!
You mentioned landing/taking off on snow. I’d be really careful there. I’ve not thought of “how much snow” I’d
try to fly with, but it’s probably half an inch or less accumulation on the operating surfaces. Several considerations here; first being that with snow on the taxi surface, you can’t see what you’re taxiing over. Some serious risks therein. Second, if you
try to brake with a snow accumulation on the surface, it’s likely the wheel will lock up and pile snow in front of it--quickly. Depending on conditions, it may not start turning and “jump over” the snow berm when you release the
brake; you have just locked up one wheel, for all practical purposes. Did I mention “gentle on the controls”…should have also said SLOW and steady.
This is by no means a complete discussion/consideration. I’m sure others have LOTS more experience with
Lancairs, and can offer better/more advice. I’ve put too much time and money into my airplane to want to just go out and experiment with adverse conditions--anytime. I’m not saying that I won’t go at all; just that my “minimums”
change. The fact that you are thinking ahead about these things is probably your best defense--and preparation…just be careful!
My two cents; views of others?
Bob