BoilerWings

So there I was, I showed up to work this morning (141 flight school) to find that a few instructors started to fly IFR flights only to turn back b/c of icing conditions (unforecasted). I have not had much experience flying in ice, mostly because I avoid it like the plague, but it was the hot topic of conversation around the coffee pot today.

My position is avoid it, fly another day, and if you suspect that you're going to see some ice on a flight, have a plan B, C and D to get out of it ASAP. What I lack in experience in dealing with ice I make up for in conservatism (AKA, I stay away from the stuff). I'd like to expand my knowledge about this though.

What additional wisdom do you all have regarding flying GA airplanes in ice? How much ice can a 172 or a Warrior really carry? Are there any "I learned about flying from that" stories to share?

Stormy Knight

Been a lot of years since I've spent much time in GA, but well I remember. Any "old school" airplane will carry a LITTLE ice (I have no experience with composites such as Cirrus and the like, and would worry a LOT there). Like with anything else in aviation, DO NOT PANIC if you get some. DO begin immediately to GET OUT. Careful study of the wx patterns before you take off, and paying attention to outside air temp as your trip progresses is critical. You should KNOW before ice begins where to go to get out of it. Do not plan on climbing out of ice in a small airplane: any airframe ice at all will likely prevent a climb. If you know that you can get ice-free by turning around or descending you can be a little braver. If you do carry ice to the airport, get a long runway and add lots to your approach speed. Delay dropping the ldg gear. Cycle the prop control in and out of high (remember that it is icing too).
If you are going to use a small airplane as transportation in the North country, you are going to meet up with ice, but remember: if you have no anti- or de-ice, it is a real EMERGENCY that you must deal with NOW.

rickair7777

Stormy is right on. I am in no way advocating intentional flight into icing conditions, but most older GA airplanes can carry a fair amount. I know plenty of people who have done so and it's not uncommon. I say this because if you over-react to a little light rime ice and panic, you could turn a common and controllable situation into a disaster.

If you fly in an ice-prone area, make sure you a ready for an inadvertent icing encounter...

1) Know your POH procedures for icing (by memory).
2) Study up on where/when icing occurs in the local airmass. Find out of if severe icing, especially severe clear ice, is likley in your area...this is bad.
3) Ask an experienced local where the icing is likely to be found (they'll know).
4) Have an escape plan based on your airplane, the local terrain, and loacl airmass condition.
5) Check Wx reports (including PIREPs) before and during flight,
6) Stay calm, execute your plan, coordinate with ATC.
7) Monitor the aircraft for performance problems or instrument malfunctions.

If you have to land carrying ice, follow your POH procedures...they will probably tell you to not change the flap setting and to land fast to account for unkown aerodynamic properties of the wing. The more ice, the faster you want to land. Ideally, if you can climb/descend into warmer air or even sunshine, you may be able to melt the ice before landing. This could take a while and would depend on your fuel situation (you will burn fuel faster at an unpredictable rate if carrying ice).

Rexflyt

Boiler the above comments are very good. About ten years ago during my instrument training in a warrior my first flight in actual which was during winter at night in the Pacific Northwest, we planned to fly a simple departure and fly a 10 mile arc to the ILS. The ceiling was at least 2000, immediately upon entering the clouds we started picking up ice, my instructor who was very new didn't ask for any deviations of any sort, we just kept flying our course to intercept all the while he kept looking out with the flashlight at the wings. We had full power in and we were barely able to hold 80kts, the plane was shaking pretty bad from prop ice and my instructor was very quiet. We flew the ILS in and fortunately he had enough sense to tell me not to use flaps, the plane just kinda plopped onto the runway. After shutdown we measured at least 3/8" of ice on the wings, spinner, and some of the prop. I said all this to remind people that going to just "take a look" can be fatal. I logged .6 that night and wrote myself a note just to remind me.

TXTECHKA

i had a similar experience with clear ice while instructing, unforcast. Don't use flaps, keep your speed up, stay high on the glideslope so you can trade that for speed if necessary on final, use a long runway, may have to open the small side window or cessna windows cause you probably won't be able to see out front. The radios will also sometimes get pretty staticy cause of the ice build up on them. If you have to descent through icing, do it fast. Be careful in the flare since the airplane isn't so aerodynamic anymore and ice adds a lot of weight to the plane. I know a cherokee will carry a lot. Had half an inch on one once, pretty nasty but don't panic and you'll be alright.

BoilerWings

I appreciate the wisdom everyone! I've only been in ice twice. The first time I was flying a Comanche at 6000, bases were at 4000 so I just descended below the clouds and was fine. The second time I was flying single pilot IFR at night in a 172. I had no idea what the tops were, but the bases were around 1700 AGL. I started to build some light rime and decided the trip wasn't worth it. Went back home and landed and flew the trip the next morning in clear skies. Both times I managed to accumulate no more than a trace of ice, but any ice makes me feel uneasy in a light GA airplane that isn't properly equipped.

I love the feedback and stories!

Scenario: I'm flying at night, pick up some ice on the climb and break out on top of the clouds. Will the ice sublimate away at night? Or do I need sunlight for that?

Stormy Knight

Sublimation is a function of the drier air outside the cloud, not sunlight, so yes, if the ice is light enough and you are on top long enough, it will sublimate. If you bet on this to get you out of trouble, you will eventually be a statistic.Tops are constantly changing, and your plan to climb out of the icing and lose it on top is a real game of Russian Roulette.

BoilerWings

Agreed! My question was purely a question of physics/chemistry; not a strategy. I actually found a quick source for those interested. Sublimation.

Stormy Knight

A good citation on the topic, however the article states that the addition of energy through sunlight is necessary, but my experience is that ice will sublimate at night. Perhaps it won't happen in a lab, but it does on a wing. I suspect that aerodynamic friction may well be the source. Therefore, ice would sublimate much faster off a jet at 450K than off of a Piper at 100 K.

rickair7777

Ice will certainly sublimate without any outside addition of energy...but very slowly. Sunlight sure helps, and so does aerodynamic friction if you go fast enough. Pilots of fast aircraft use Total Air Temperature (TAT) for determining risk of icing...this takes into account the aerodynamic friction heating. The actual air temp could be at or below freezing, but if the TAT is above freezing by a certain margin icing is unlikely to occur.

I suspect that you would not be able to sublimate much ice at night within the fuel endurance of a GA plane, unless you were going fast enough to get some significant aerodynamic heating (probably > 150 kts).