Dangers of flying in snow

[topcat450]

After nearly getting caught out in a snow shower yesterday (I could see the snow just hitting the far end of the runway as I was on very short final), i was curious what were the main dangers of flying through a snow shower?

Is it just the (seriously) reduced viz? Will is cause airframe icing or at 80kts will it just 'blow' right off?

Editing to say - and yes... I learnt quite a bit yesterday so try not to just abuse me for cutting it so close, I've beat myself up about that plenty.

[timmcat]

i was curious what were the main dangers of flying through a snow shower?

eeerm... a rapid cessation of flying would be a tad disappointing one would think...

(OK - non flyer prooner will now skulk off back to JB..)

[Aim Far]

I ended up flying in a snow shower at the weekend for a couple of minutes. It was quite fun - a bit like the stars on the old windows screensaver. I had a way out - I was skirting round the edge of the cloud - so I wasn't too worried. The snow wasn't sticking to the airframe, maybe it was too cold? I suppose the problem is you just can't tell whether its going to stick or not. Other dangers would be induction icing.

[Snigs]

Apart from all of the obvious issues, it's IMC (you know, a whiteout)..... are you qualified?

[bookworm]

It's very unusual for snow to stick to the airframe in the air -- it's already frozen. Impact icing in induction systems etc. is possibly an issue. But as you've realised, the biggest problem is the white-out effect.

[Capt. Manuvar]

Unless the snow is totally dry, i wouldn't go on a flight with the presumption that the snow will blow off. Snow can be very sticky. If you are not IMC rated i wouldn't underestimate the danger of whiteout. I had a chance of flying in Canada this winter and experienced a bit of white out. In snow the visibility can decrease very rapidly.
Of course airframe icing is not a joke. I was once in a C172 that had picked up some ice and could barely maintain 80KIAS in level flight at full power.
If your a/c isn't equiped for flight in known icing you shouldn't be flying in any kind of precipitation when the temps are below frezzing which i guess it would have been when it was snowing.

[High Wing Drifter]

There was a case where a RAF Jag pilot landed well short because the maitenance crew only cleared the mid section of the runway. Beacuse the pilot just maintained the correct out of the window look he was decieved into thinking he was higher than he was.

[slim_slag]

Snow can be VFR too, but you need to be careful as that can change quickly. Good rule of thumb when flying VFR is never fly into a shower if you cannot see through it to the other side. Flying in snow is the sort of thing you need to do first with somebody who has done it before. Better to pick your way around the showers if you can. Ice can happen, snow can be 'wet', apply same rules as when flying in rain.

[Final 3 Greens]

If the snow is caused by a Cb or large Cu, there may be severe turb associated with the gust front and downdrafts - beware.

[Mosspigs]

Aside from the mechanics of the snow and control surfaces etc etc , one of the most concerning aspects of flying in snow is if VFR, the "stars" that you alluded to can cause spatial disorientation.

At the very least they can cause a distraction that could lead to break down of a scan. Unless you are a super cool pilot, if you don't have an IMC, the chances are you aren't, which you will not notice that you are climbing or descending. This can lead to a very emotional time.

[englishal]

I flew through a couple of showers on Saturday as well....no problems were experienced...

[Kolibear]

Driving through snow can be very disorientating, even mesmerising. Snow packing in the air intake system could also be a problem too, the snow can build up on any mesh filter upstream of the throttle and air filter.

[Aussie Andy]

I recently had my first encounter with serious snow in IMC - the evening before my IMC rating flight test... if you'd like to scare yourself about snow, then read this !!!

http://www.pprune.org/forums/showthr...57#post1708157 (scroll down to the paragraph beginning "Before I go..."

Essentially I was OK as we were IFR and got ourselves a radar service etc, but there were a few people VFR on the frequency at the same time all trying to get back into Wycombe - and it was a bit scary for one bloke in particular who very nearly didn't make it, but with help from D&D (three times!) he eventually got down... just!

Andy

[bookworm]

Unless the snow is totally dry, i wouldn't go on a flight with the presumption that the snow will blow off.

Lest there is any misunderstanding reading this comment in the context of mine above, I don't think that snow will stick to a clean wing in flight: if it's frozen, it's frozen -- if it's partly melted, the temperature is above freezing and icing is unlikely.

But there's a huge difference between that and assuming that snow that has accumulated on the wing on ground will "blow off" during flight. Different processes may occur when the snow starts to accumulate, and to depart with snow is at best illegal and at worst suicidal.

[Genghis the Engineer]

I've flown in snow twice, neither deliberately, and both briefly.

Once in a PA28, through light falling snow. It was rather like the ubiquitous windows screensaver, but nothing formed onto the aeroplane, and no ill effects were experienced.

The other was in a flexwing microlight, when it plastered on my helmet, arms, body and (I assume) the leading edge of the wing. It was very alarming indeed, I was basically in a total white-out - I couldn't even read my instruments. Thankfully it only lasted a few minutes (and I could maintain basic attitude information by looking out the side); by the time I landed (about half an hour later) there was none left. I didn't notice any handling problems, but on the other hand was being incredibly careful to maintain straight and level with good speed. It is not an experience I have any desire to repeat !

G

[BigEndBob]

Be very careful not to get caught out in a whiteout situation.
10 minutes of heavy snow can completely cover runways, vis can drop to 1/2 mile or less and even at 200 feet the only way you know which way is up visually is by knowing tree trunk generally point toward the sky..or is it the other way round!

[Tinstaafl]

Very common in the Shetland Islands. It takes very little snow to change VMC into IMC. Even worse, a seemingly benign snow shower can quickly become not so benign even while still flying through it.

[Mosspigs]

Aussie Andy,

Good post but doesn't put Wycombe in a good light.

400' cloud base and snow showers yet they told you to level off in cloud at 3500'. That must be icing conditions for which the PA28 isn't cleared.

That said well done for passing.

[bookworm]

Good post but doesn't put Wycombe in a good light.

400' cloud base and snow showers yet they told you to level off in cloud at 3500'. That must be icing conditions for which the PA28 isn't cleared.

Not quite sure I understand your comment. Wycombe doesn't offer an IFR Approach Control Service. Andy (or his instructor) was entirely responsible for the choice of level and route.

Even if they were providing IFR Approach Control, it's not their responsibility to decide on flight conditions. It's for the pilot to refuse any clearance for which his aircraft is not suited. If the pilot asks for a clearance at a weather that's unsuitable because of weather, it won't be withheld for that reason.

[Droopystop]

I appreciate that dry snow would not stick, but we do not get dry snow very often in the UK. Certainly in every snow shower I have flown in (and there has been a few) snow has always stuck some where on the airframe. No one has mentioned propeller icing and being a rotorhead I don't know how likely that is. But on a helicopter there is sufficient friction to keep the blades a few degrees above ambient. I am guessing that a prop at 2500rpm has more friction and is therefore warmer. So could there be a scenario where you flying in say -2degrees in snow and the prop is a freezing or even minus zero as the met men would put it and you get prop icing?

More importantly is departing just after a snow storm. Been a number of terrible accidents where wings have not been properly cleared or snow accumulated in coamings have been sucked into the engine.

But flying on a clear day after snow is breathtaking.