Flight into known icing conditions

[cookmg]

It was suggested that I try this post over here as many of you folks might be very experienced with this subject. Thanks for the info!

As a newly minted instrument pilot, I would like to know how more experienced pilots deal with the threat of ice at cruise. If you are flying a basic SE (172, cherokee, etc.) do you never depart if you anticipate possible light ice? How important is it to have backup plans?

Consider, if the MEA for your route is 4000, the ATC preferred altitude is 6000, the temp is -1C at 6000, the temp is 12C at terrain/airport elevation across route, there are NO airmets or sigmets for icing, there is 1 pirep for light rime at 6000 along route. You could take 6000 and if you pickup ice ask for 4000. If you don't get it you might have to ask for priority or even declare an emergency. Since this could have been avoided given the indications of ice, is this negligent operation of an aircraft?

Basically, I'm looking for some general thoughts on operations near ice . . even light ice. How does the picture change when the flying is for hire? If you are flying light SE/twin NO deice boots under part 135, do your cancellation standards change?

If I cancel a flight everytime there will be clouds at my cruise altitude and the temp is below freezing am I cancelling too often?

Thanks.

Mike

 

[Benzene]

Since light ice can become severe in a matter of half an hour or less determining where you fly, it is not a good idea to depart into known conditions in an unprotected aircraft. Just this last Winter a guy went into light conditions in his unprotected 172, landed at one airport to check out the amount of ice, then departed and later crashed his plane thinking the rate of accumulation would remain a constant. Ice can become a problem with aircraft authorized into this nasty stuff. Wether it is 91/135/121 playing the odds are never a good idea.

 

[Buckeye]

Mike if you want to live long in this industry you will avoid two things, ice and thunderstorms. Ice has killed many good compentent pilots that pushed their luck a little to far, and T-storms imbedded can kill you just as quick. Most professional 135 outfits will not fly aircraft in known icing conditions that are not approved, infact there are few if any that will even try. Just because you have ice protection doesn't mean that you are untouchable, people have been killed or injured as well in these types of aircraft. I myself would never think of flying in a cloud with the temp much below 5 C in a 172 or anything else that is unprotected. I have been in a DC-3 when it iced up faster than the boots could shed it, it wasn't any fun. If it doesn't feel right, sound right, or you have to logically justify it in your mind don't fly. Fly safe and be careful!

 

[upndsky]

Let me first say that icing is nothing to be triffled with. It can, has and will kill pilots, good and bad. Treat it with respect.

Having said that, though, the perceived threat of icing should not be an automatic no-go. One must weigh several factors into the decision whether to launch or not. To begin, consider the risk/benefit factor. If you're going up for pleasure or training, I'd say forget about it and try another day. Otherwise, consider these factors: There is a big difference between forecast icing and actual icing. Pireps play an important role here. Always consider the source: light ice on a Boeing 757 is not the same as light ice on a C-172.

Also, icing typically will occur in small areas at altitudes no more than 4000 feet thick. And when I'm talking small areas, I'm talking about 10 or 20 miles. It's not unusual for you to pick up some ice when a pilot 20 miles ahead or behind you isn't. Aircraft icing is still one of the least understood phenomena facing meteorologists today. Because they can't accurately forecast exactly where icing is going to occur, they put out these blanket icing forecasts that can cover several states, when in fact icing will occur only in certain isolated patches. It's their way to cover their butts (not that I can blame them).

Because icing occurs in narrow bands, it's possible to get out of it just by climbing or descending a couple of thousand feet. If you tell a controller you need an altitude change because of ice, they'll bend over backwards to accomodate you. I've never heard of a controller refusing such a request. And if he/she does, declare an emergency.

Then you have to look at exactly where on the airframe you're picking up ice. Things that stick out in the slip stream, like temperature probes and pitot tubes (turn the pitot heat on!!!!) will ice up before the wings. I've flown around with ice on some parts of the airframe but have the wings and tail completely clean. It's also possible to build up a thin layer of ice without it getting thicker. How? Beats me, but I've seen it.

As far as having to go if flying for hire, the freight company I fly for is very good about grounding our non-ice planes when it's clear there's going to be ice. Our known-ice planes will fly though. On that subject, known-ice isn't meant for you to keep flying in icing conditions. It's only there to buy you time to get out of it.

So, moisture + 0 degree temps does not automatically equal ice. Look closely at pireps and winds aloft forecasts because there may be an inversion somewhere. Leave yourself an out. If you where ice free a minute ago, go back to that place. And if there's not absolute need for you to be flying that day, stay home and read a good book about icing. Knowledge about when and where you can expect to find it is key to making the right decisions. Good luck.

 

[cookmg]

Thanks for the thorough replies. I have learned a lot.

Mike

 

[Snakum]

Me too!

Minh

 

[Future SNA]

I think the saying is a change in altitude of 3,000 feet or a deviation of 50 miles will clear you of 90% of the icing you encounter.

 

[Airpiraterob]

respect the ice young grashoppah...

even a good plane with the equipment is not enough. this is why you dont even mess with it. it takes one big scare to realize.

february 2001, between buffalo and utica NY. 8000 feet. forcast was for light ice. reported was light ice. forcast was for all morning till about noon or so, then nothing. plane: Cessna 208-NO POD underneath. the caravan isn't the best ice plane by far but this stuff turned into freezing rain right away and fast accumulation. the plane goes 170 knots normally. book says minimum icing speed is 110 knots. i was at 120 in no time, not able to climb. my only out was down. maximum defrost on and hotplate on and inertial separator on. torque (power) needle was half on redline. boots were totally clean and shiny, the wings had stalagmites and stalagtites..or the uppy and downie thingies on the top and bottom surfaces. classic roll back ice. im not bragging, but please use this as what can happen. im not proud of having carried this much ice.

i let down to 4000, no more rain. no more ice. but i was at 125 kts the rest of the way home. so whatever you pick up, youre gonna drag along if it wont melt. only takes 5 seconds for that snow to become freezing rain, or 5 seconds for that mist to become bad ice. will you notice it just as fast?...nope. usually takes a few minutes before you realize youre taking on ice. can be too late by then. i dont want to scare you, just be very careful. If enyone knew fernando (ALB lounge), they know how bad it can get ...

 

[Singlecoil]

My ice story...

A flight on the rocks? February 6, 1995

The native girl cautiously creeps toward the barstool. A bush pilot is draining a cold one after earning his daily pay. “Excuse me, were you my pilot today?”
“Oh, that was you from Brevig Mission?”
“That was such a scary flight!”
“Oh, well, umm, I’m sorry about that, I didn’t think the weather was going to be that bad or I wouldn’t have taken any passengers.”
“It was so white and there was all that ice on the airplane!”
“Well, I didn’t get any ice on the way up, and it was kind of unexpected. By the time we were icing up, there was little to do but get to Nome as soon as possible, and then we taxied into the snow drift, it was too dark to see.”
“I was so scared, I was wishing I stayed home, but I’m glad I got here safe, and I’m glad you were flying, and…will you dance with me?” Like I’m going to turn that down.
The weather was not forecast to get below 3000 feet with ten miles of visibility. Now I know why they call them “weather guessers.” My gut was telling me that something was rolling in, but we had lots of mail and our other plane was broken, so I kind of had to take a look. I think I’ll listen to my gut a little more the next time.
The first twenty miles north were a pretty solid white-out, but the weather improved from there and my first two stops were uneventful. In Wales I had to wait 30 minutes in an 80 below wind chill for our agent to show up, making the flight late. Wales had warmed up from a 101 below wind chill earlier in the week. I took off and called Nome to extend my flight plan. They answered by telling me Nome had gone down to a 600 foot ceiling with a half a mile visibility, essentially closing the airport. I headed to Teller to wait out the storm at our agent’s house. I was there for 90 minutes with another pilot, admiring the agent’s collection of gold nuggets from his 15 claims.
Nome came back up to three miles so I went to Brevig Mission, only 8 miles from Teller, to load up passengers and head for Nome as darkness approached. We were following the coast only about 30 miles from Nome when it started—freezing rain. The worst kind of icing with the fastest accumulation rate, and of course, a 207 has no de-icing equipment. In 15 minutes, the wings, tail, and prop were covered, forcing me to use full power to keep from descending. My defroster was working well so I had a little hole in the windshield I could see out of. The clouds were low and full of more ice so I couldn’t climb to find warmer temperatures. The passengers kept looking at the wings, then at me, then at the ground, then at me, etc. I naturally ignored them and acted as if this always happened. The wind had increased to a thirty-five knot headwind, slowing my progress and lengthening my time in the icy rain. Nome weather had come back down to a little over a mile, forcing me to get a clearance to approach the airport. Usually this means a ten to thirty minute delay, far too long in these conditions; the airplane wouldn’t fly that much longer if I kept putting on ice. I was thinking I would have to declare an emergency to get first in line to land when the controller told me there was no other traffic. Lucky—an emergency commands lots of unwanted attention, and even more unwelcome paperwork.
Two miles out I saw the runway and lined up. I reached for the flap handle but caught myself. Ordinarily flaps will allow the airplane to fly safer at slower speeds, but with this much ice on board, it would surely stall the tail and nose in. I touched down smoothly with no flaps and started to taxi in. In the darkness, I managed to find a snowdrift, forcing us to shutdown and deplane. I pointed in the direction of the terminal, and the two ladies on board walked off, saying nothing. I noticed the two men looking at the ice on the wings and shaking their heads. I had to inform them that the ice was unexpected and to my surprise they thanked me for the flight and helped me push the plane out of the snow. I quickly ran next door to see if I could put the plane in a hangar before the FAA saw it. I chipped a piece off the tail and one off the wing; perfectly clear, thick ice. I closed out my paperwork and headed for town. What does a pilot do with thick chunks of ice from his wings? He puts them in a glass and pours scotch over them; after all I had the next two days off.

 

[SpocksBeard]

I'm no expert, but my ground rule for myself and my students is simple: If the temperature is below zero in the clouds where I need to fly at any point in the flight, I don't go. Airmets aren't guaraunteed icing but every time I've flown in the clouds when there was an airmet I got ice. The only time I ever go into the clouds when the temps are below 0 is when there are no Pireps for that area and I want to show a student what a little ice might look like. I ONLY do this when I can descend out of the clouds (not just to warmer temps) and be at a legal/safe IFR altitude.