Icing can get out of hand in the strangest places.
The last time I picked up a load of ice where I could not maintain altitude at max allowable power was over Cairo Egypt in the winter of 2000.
Known Icing Aircraft
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Chuck Ellsworth
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Re: Known Icing Aircraft
The most difficult thing about flying is knowing when to say no.
After over a half a century of flying I can not remember even one trip that I refused to do that resulted in someone getting killed because of my decision not to fly.
After over a half a century of flying I can not remember even one trip that I refused to do that resulted in someone getting killed because of my decision not to fly.
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Chuck Ellsworth
- Rank 11
- Posts: 3074
- Joined: Sat Sep 22, 2007 6:49 am
- Location: Always moving
Re: Known Icing Aircraft
It is half of a 360 manoeuveur.
The most difficult thing about flying is knowing when to say no.
After over a half a century of flying I can not remember even one trip that I refused to do that resulted in someone getting killed because of my decision not to fly.
After over a half a century of flying I can not remember even one trip that I refused to do that resulted in someone getting killed because of my decision not to fly.
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goldeneagle
- Rank (9)
- Posts: 1348
- Joined: Mon Jan 02, 2006 3:28 pm
Re: Known Icing Aircraft
Ok, so I wasn't going to post here anymore, but, this is a topic that makes people dead, and does so quickly if/when they get stupid and/or bad advice.
I fly a piston twin that's 'certified' for known ice, and I've spent 30+ years flying, the vast majority of it on the west coast, where winter + ifr = ice, pretty much every day.
First, the difference between 'equipped' for known ice, and 'certified' for known ice. It's NOT just paperwork. Take a good look at the differences between a C-421 (just one example airframe I'm very familiar with) early model 'equipped' for ice, and one 'certified'. Here's what you will find changed on this model as they went thru the 'certification' process.
a) hot plate or alchohol windshield swapped out for a hot glass windshield. It's a $50,000 item to replace, and the reason there is a $50K difference between the prices on the model years pre/post certification.
b) 50 amp alternators swapped out for 100 amp alternators. This allows for the electrical system to carry the de-ice and anti-ice equipment with one alternator failed. That windshield draws 50 amps on high.
c) Heated static vent ports.
d) Heated fuel vents.
e) Redundancy and fail safe modes built into the vaccuum system that drives the boots.
f) Boots added to the wing roots between the nacelle and the cabin.
g) Independant pitot/static on left/right panel sides (only left side heated).
There's a few more details I cant remember off the top of my head, but, the essence is, while _most_ of the difference between 'equipped' and 'certified' is paperwork, in reality, the systems themselves are improved. Do NOT be fooled by 'equipped', and believe it's the same as 'certified' on models that were produced in the before/after certification push during the 70's. Look at the POH in the airplane you intend to purchase, look at the addendums. If it's 'certified', there will be an addendum on the icing systems, and it will reference that airframe, by serial number. None of the early models came from the factory with a blanket certification across the model, it was an option for all of them, and required numerous systems changes. But, again, using our example, the 421, cessna produced the airplane for a number of years before they did the certification. NONE of the ones produced before they went thru that process are actually 'certified', and, of the ones produced after that, the only ones that are truely 'certified' are the ones delivered from the factory with the options required, and that will be referenced in the POH for the airplane in particular, by serial number. I dont remember the exact years offhand, would have to go look it up to be precise, but, if memory serves me correctly, in our case, cessna did the certification in 75. That means, no 421 produced prior to that is 'certified' unless somebody did a lot of STC add ons. All of then produced after that were eligible, but, only those that left the factory with the extras listed above were truely 'certified' by cessna.
Another big 'paperwork' difference. If you are flying commercially, and want to go from yvr to yka during the winter, the 'equipped' airplane is going to spend many days sitting on the ramp due to weather forecasts, the 'certified' airplane can blast off and go look. This is not such a bad thing, the VAST majority of the time, the flight is done between layers and ice is not a factor anyways, but, if the forecast says there's going to be ice, the airplane must be 'certified' in order to avoid those pesky registered letters.
When I got the first registered letter, I had to head on down to 800 burrard one day, and show the folks from enforcement the addendum to the POH that specifically says 'certified' for known ice, and it references our airframe by serial number. I had paperwork along to show the airplane is 'certified' for flight into known ice, the crew had been trained in operations during icing conditions, and, we had the printouts of the weather forecasts that the pilots (me being one of them) had made prior to departure. I also had operational flight plans that showed a filed trip at 16,000 which was forecast to be between layers. On the trip in question, climb proceeded normally to 12,400 where we entered cloud. VSI on both sides showed zero as we hit 12,800, so either the airplane picked up a LOT of ice very quickly (it did), or both static sources had frozen over (not very likely). The buffet starting in the tail was the big clue, so I advised ATC that we were unable to continue the climb, told them I was descending to get out of the ice, and poked the nose down. That caused a bit of a scramble for the ATC folks, and, was the ultimate reason I got the registered letter. This event did cause a bit of a flurry on the radio as ATC started hammering out vectors to other airplanes, in a scramble to ensure separation between me and another airplane filed at 10,000 running about 15 miles behind us on the same route.. But the key here was, I didn't ask for the descent, I advised ATC that I had a sudden and severe accumulation, and was initiating a descent to below freezing level. After my talk with enforcement folks, they agreed, I did it all 'by the book', my paperwork for filing into icing conditions was in order, and I had made a smart decision to descend. It became a 'non event' for the enforcement folks. If my airplane had been 'equipped' but not 'certified', that would have resulted in an enforcement action.
Ok, now that's the 'paperwork' side of the equation. We still have the 'lets stay alive in the real world' side of the equation. On this subject, I agree with Hedley to some extent, but, I gotta add a few things to what he says. First off, to 'safely' fly into potential icing conditions, he's right, the turbocharger is an absolute requirement for a piston airplane, you gotta have the power available at altitude that allows you to climb on thru, and get on top. Without it, you dont wanna try climb thru the layer. You need that oxygen system too, typically out here in this part of the world, the 'between layers' cruise is available somewhere between 14 and 20 thousand. Personally, I dont like sucking on a mask, so, I include 'pressurized' as mandatory, but, if you dont mind the mask, O2 is 'good enough'. For me, personally, another item I have on the 'must have' list, is sufficient redundancy that I can maintain the 'on top' with any single system failure. That implies a pair of fans for me personally. That's another whole debate subject I wont get into here, to far of this ice topic.
So, now comes the item nobody else seems to every mention, de-icing systems. The absolute best de-cing system every invented is rain. That's right kiddies, nothing will de-ice and airplane faster than flying thru a rain shower at 160 knots. So, the key to safely dealing with icing layers out here on the wet coast, is knowing where to find rain, and the answer to that is dirt simple, below the freezing level. And, if you are climbing thru a layer of ice accumulation, assuming you started out below the freezing level, you know EXACTLY where it is, you watched for it on the way up, and made a strong mental note of it.
Now, armed with this knowledge, it becomes easy to stay safe in icing conditions, dirt trivial simple. Here's how it works. First we assume, anytime we enter icing conditions, even light rime, it can change to severe clear and ice up the airplane like a popsicle in a heartbeat. Even the most heavily iced airplane is still controllable 'strait ahead and descending', so, as long as we can get back down to the rain, the situation can be 'unnerving', but it wont get scary or life threatening. The assumption therefore is, never assume you will be able to out climb the ice, always assume it's going to suddenly become servere, and take you down to the freezing level, like it or not, you dont control that part of the decision.
With this assumption in mind, you come to a simple operational conclusion. When flying in potential icing conditions, we climb thru the ice only in areas where the MEA below us, is well below the freezing level. That means, no matter how bad it gets during the climb, the worlds best de-ice system is 'descent, strait ahead'. Use the same rule for descent, we never descend into the icing layer until the MEA below is well below the freezing level, and once we enter the layer, we assume the descent is committed, cannot be stopped, and 'level off' is NOT an option. Sometimes this means, while climbing out, ATC will question you with a big 'huh' as you ask for climbing holds to get on top, or, while coming into the lower mainland, ATC gets mildly annoyed when you are cruising at 17,000 coming into the KEENE intersection, and refuse the descent with the verbiage 'we will stay up here until over the straits due to ice'.
If you know and understand the freezing level, then you know how to take advantage of the worlds best de-ice system, the rain shower. Between the west coast and the interior, during the winter, there's a LOT of ice. But, plan your flight to be above the ice and in the clear BEFORE the mea jumps up above the freezing level, then do the same for the return, stay above and in the clear till the mea is below the freezing level, the ice will never kill you. BUT, if you accept that descent 25 miles before KEENE, and expect to level off at 10,000 and carry on till the MEA steps down again, one day, you will descend into those rocks, and have no way of stopping the descent in an airplane iced up like a popsicle. But, delay that descent 40 miles, poke the nose into the clouds when the MEA below is down at 3000, with a freezing level of 5000, it will simply AMAZE you how fast something like a 421 can descend with a load of ice on, and even more amazing, will be how fast that stuff can accumulate with all systems running full blast. On more than one occaision I have poked the nose down into the white stuff over the straits after passing KEENE at 17,000, then watched the VSI peg out on the bottom as we come screaming down thru a moderate to heavy accumulation.
I timed it once, entered cloud around 16,200, freezing level at 5200, descending at 145 indicated, 25 inches of mp, cycling boots about every 30 seconds. The airframe started clearing at about 5400, you could hear the stuff coming off, and see the windscreen on co-pilots side go quickly, we levelled off comfortably at 3000 in less than 4 minutes after starting that descent, we were thru the freezing level in less than 3 minutes. I dont think takeoff power could have stopped that descent thru the normal stepdown at 10,000. On the day in question, the fella with me in the right seat was a relatively new commercial pilot, had never really done any operational flying in ice. He didn't really undestand my fixation on freezing level before the trip, but, when we got on the ground afterwards and de-briefed, he really and truely understood my fixation on freezing level. 421 is a slippery airplane at the best of times, and even with full flap and gear hanging out, with 25 inches of mp and 145 indicated, you'll be hard pressed to get 3000 fpm descent out of the bird. We came down thru the ice no flap at 145 indicated, 25 inches, and were seeing 5000fpm descent rates, that's a LOT of drag. Granted, the day was pretty severe, and it was WAY worse than I expected, but, my little rule about 'descent strait ahead to freezing level' made it manageable. If I had accepted the normal descent profile clearance on that day, I wouldn't be here to type this today.
Equipped for ice gives you the option to deal with the situation while you turn around and go back to where it wasn't icing. Certified for known ice gives you the option to flight plan accordingly, and makes you legal to file and fly on days when you otherwise couldn't. To many folks somehow think that either of these options also includes the option to be stupid, but, that is not the case. 'Certified' gives you flight planning flexibility, but, the real world doesn't change, you still have to know and understand the worlds best de-icing system. Never put your airplane in a situation where 'strait ahead and level' while accumulating ice is a requirement to stay alive. Always cross the rocks on top, or between layers, at an altitude your airplane can maintain with one fan shut down. You only intentially fly into an accumulation layer where 'strait ahead down to freezing level' is an option, or the worst case is, 'turn around, strait back, down to freezing level' is the alternate option. If picking and choosing routes that allow this option is not possible, even the airplane 'certified' for known ice stays parked on the ground.
I learned the freezing level lesson one dark evening in october, during the early 80's, on the booth arrival to vancouver in a lightly loaded chieftan. You never want to see the altimeter unwind to below MOCA with throttles pushed to max and blue line speed set on the dial. I've been there, done that, once, and lived to tell about it. It's never going to happen to me again. I fly a light twin on the west coast where we see a lot of ice in the winter, and I'm comfortable knowing that as long as 'find the rain back' is an option, we can safely navigate thru the accumulation layers.
I know, this is a LONG rant, but, the crux of it all is this. 'Certified for known ice' does NOT mean 'Certified for stupid'. What it does mean, is, more flight planning options, and, a real need to know and understand ice on airframes if you intend to use those options. In other parts of the country, things may well be different, but here on the west coast, knowing and understanding freezing levels is the key to safely operating in these conditions. No money in the world can buy the comfort of 'rain' for an iced up airframe. Leave yourself the 'directly back to the rain' option always open, and, you will live to fight another day. Close that option, and one day, the rocks may well reach up and swat you out of the sky.
I fly a piston twin that's 'certified' for known ice, and I've spent 30+ years flying, the vast majority of it on the west coast, where winter + ifr = ice, pretty much every day.
First, the difference between 'equipped' for known ice, and 'certified' for known ice. It's NOT just paperwork. Take a good look at the differences between a C-421 (just one example airframe I'm very familiar with) early model 'equipped' for ice, and one 'certified'. Here's what you will find changed on this model as they went thru the 'certification' process.
a) hot plate or alchohol windshield swapped out for a hot glass windshield. It's a $50,000 item to replace, and the reason there is a $50K difference between the prices on the model years pre/post certification.
b) 50 amp alternators swapped out for 100 amp alternators. This allows for the electrical system to carry the de-ice and anti-ice equipment with one alternator failed. That windshield draws 50 amps on high.
c) Heated static vent ports.
d) Heated fuel vents.
e) Redundancy and fail safe modes built into the vaccuum system that drives the boots.
f) Boots added to the wing roots between the nacelle and the cabin.
g) Independant pitot/static on left/right panel sides (only left side heated).
There's a few more details I cant remember off the top of my head, but, the essence is, while _most_ of the difference between 'equipped' and 'certified' is paperwork, in reality, the systems themselves are improved. Do NOT be fooled by 'equipped', and believe it's the same as 'certified' on models that were produced in the before/after certification push during the 70's. Look at the POH in the airplane you intend to purchase, look at the addendums. If it's 'certified', there will be an addendum on the icing systems, and it will reference that airframe, by serial number. None of the early models came from the factory with a blanket certification across the model, it was an option for all of them, and required numerous systems changes. But, again, using our example, the 421, cessna produced the airplane for a number of years before they did the certification. NONE of the ones produced before they went thru that process are actually 'certified', and, of the ones produced after that, the only ones that are truely 'certified' are the ones delivered from the factory with the options required, and that will be referenced in the POH for the airplane in particular, by serial number. I dont remember the exact years offhand, would have to go look it up to be precise, but, if memory serves me correctly, in our case, cessna did the certification in 75. That means, no 421 produced prior to that is 'certified' unless somebody did a lot of STC add ons. All of then produced after that were eligible, but, only those that left the factory with the extras listed above were truely 'certified' by cessna.
Another big 'paperwork' difference. If you are flying commercially, and want to go from yvr to yka during the winter, the 'equipped' airplane is going to spend many days sitting on the ramp due to weather forecasts, the 'certified' airplane can blast off and go look. This is not such a bad thing, the VAST majority of the time, the flight is done between layers and ice is not a factor anyways, but, if the forecast says there's going to be ice, the airplane must be 'certified' in order to avoid those pesky registered letters.
When I got the first registered letter, I had to head on down to 800 burrard one day, and show the folks from enforcement the addendum to the POH that specifically says 'certified' for known ice, and it references our airframe by serial number. I had paperwork along to show the airplane is 'certified' for flight into known ice, the crew had been trained in operations during icing conditions, and, we had the printouts of the weather forecasts that the pilots (me being one of them) had made prior to departure. I also had operational flight plans that showed a filed trip at 16,000 which was forecast to be between layers. On the trip in question, climb proceeded normally to 12,400 where we entered cloud. VSI on both sides showed zero as we hit 12,800, so either the airplane picked up a LOT of ice very quickly (it did), or both static sources had frozen over (not very likely). The buffet starting in the tail was the big clue, so I advised ATC that we were unable to continue the climb, told them I was descending to get out of the ice, and poked the nose down. That caused a bit of a scramble for the ATC folks, and, was the ultimate reason I got the registered letter. This event did cause a bit of a flurry on the radio as ATC started hammering out vectors to other airplanes, in a scramble to ensure separation between me and another airplane filed at 10,000 running about 15 miles behind us on the same route.. But the key here was, I didn't ask for the descent, I advised ATC that I had a sudden and severe accumulation, and was initiating a descent to below freezing level. After my talk with enforcement folks, they agreed, I did it all 'by the book', my paperwork for filing into icing conditions was in order, and I had made a smart decision to descend. It became a 'non event' for the enforcement folks. If my airplane had been 'equipped' but not 'certified', that would have resulted in an enforcement action.
Ok, now that's the 'paperwork' side of the equation. We still have the 'lets stay alive in the real world' side of the equation. On this subject, I agree with Hedley to some extent, but, I gotta add a few things to what he says. First off, to 'safely' fly into potential icing conditions, he's right, the turbocharger is an absolute requirement for a piston airplane, you gotta have the power available at altitude that allows you to climb on thru, and get on top. Without it, you dont wanna try climb thru the layer. You need that oxygen system too, typically out here in this part of the world, the 'between layers' cruise is available somewhere between 14 and 20 thousand. Personally, I dont like sucking on a mask, so, I include 'pressurized' as mandatory, but, if you dont mind the mask, O2 is 'good enough'. For me, personally, another item I have on the 'must have' list, is sufficient redundancy that I can maintain the 'on top' with any single system failure. That implies a pair of fans for me personally. That's another whole debate subject I wont get into here, to far of this ice topic.
So, now comes the item nobody else seems to every mention, de-icing systems. The absolute best de-cing system every invented is rain. That's right kiddies, nothing will de-ice and airplane faster than flying thru a rain shower at 160 knots. So, the key to safely dealing with icing layers out here on the wet coast, is knowing where to find rain, and the answer to that is dirt simple, below the freezing level. And, if you are climbing thru a layer of ice accumulation, assuming you started out below the freezing level, you know EXACTLY where it is, you watched for it on the way up, and made a strong mental note of it.
Now, armed with this knowledge, it becomes easy to stay safe in icing conditions, dirt trivial simple. Here's how it works. First we assume, anytime we enter icing conditions, even light rime, it can change to severe clear and ice up the airplane like a popsicle in a heartbeat. Even the most heavily iced airplane is still controllable 'strait ahead and descending', so, as long as we can get back down to the rain, the situation can be 'unnerving', but it wont get scary or life threatening. The assumption therefore is, never assume you will be able to out climb the ice, always assume it's going to suddenly become servere, and take you down to the freezing level, like it or not, you dont control that part of the decision.
With this assumption in mind, you come to a simple operational conclusion. When flying in potential icing conditions, we climb thru the ice only in areas where the MEA below us, is well below the freezing level. That means, no matter how bad it gets during the climb, the worlds best de-ice system is 'descent, strait ahead'. Use the same rule for descent, we never descend into the icing layer until the MEA below is well below the freezing level, and once we enter the layer, we assume the descent is committed, cannot be stopped, and 'level off' is NOT an option. Sometimes this means, while climbing out, ATC will question you with a big 'huh' as you ask for climbing holds to get on top, or, while coming into the lower mainland, ATC gets mildly annoyed when you are cruising at 17,000 coming into the KEENE intersection, and refuse the descent with the verbiage 'we will stay up here until over the straits due to ice'.
If you know and understand the freezing level, then you know how to take advantage of the worlds best de-ice system, the rain shower. Between the west coast and the interior, during the winter, there's a LOT of ice. But, plan your flight to be above the ice and in the clear BEFORE the mea jumps up above the freezing level, then do the same for the return, stay above and in the clear till the mea is below the freezing level, the ice will never kill you. BUT, if you accept that descent 25 miles before KEENE, and expect to level off at 10,000 and carry on till the MEA steps down again, one day, you will descend into those rocks, and have no way of stopping the descent in an airplane iced up like a popsicle. But, delay that descent 40 miles, poke the nose into the clouds when the MEA below is down at 3000, with a freezing level of 5000, it will simply AMAZE you how fast something like a 421 can descend with a load of ice on, and even more amazing, will be how fast that stuff can accumulate with all systems running full blast. On more than one occaision I have poked the nose down into the white stuff over the straits after passing KEENE at 17,000, then watched the VSI peg out on the bottom as we come screaming down thru a moderate to heavy accumulation.
I timed it once, entered cloud around 16,200, freezing level at 5200, descending at 145 indicated, 25 inches of mp, cycling boots about every 30 seconds. The airframe started clearing at about 5400, you could hear the stuff coming off, and see the windscreen on co-pilots side go quickly, we levelled off comfortably at 3000 in less than 4 minutes after starting that descent, we were thru the freezing level in less than 3 minutes. I dont think takeoff power could have stopped that descent thru the normal stepdown at 10,000. On the day in question, the fella with me in the right seat was a relatively new commercial pilot, had never really done any operational flying in ice. He didn't really undestand my fixation on freezing level before the trip, but, when we got on the ground afterwards and de-briefed, he really and truely understood my fixation on freezing level. 421 is a slippery airplane at the best of times, and even with full flap and gear hanging out, with 25 inches of mp and 145 indicated, you'll be hard pressed to get 3000 fpm descent out of the bird. We came down thru the ice no flap at 145 indicated, 25 inches, and were seeing 5000fpm descent rates, that's a LOT of drag. Granted, the day was pretty severe, and it was WAY worse than I expected, but, my little rule about 'descent strait ahead to freezing level' made it manageable. If I had accepted the normal descent profile clearance on that day, I wouldn't be here to type this today.
Equipped for ice gives you the option to deal with the situation while you turn around and go back to where it wasn't icing. Certified for known ice gives you the option to flight plan accordingly, and makes you legal to file and fly on days when you otherwise couldn't. To many folks somehow think that either of these options also includes the option to be stupid, but, that is not the case. 'Certified' gives you flight planning flexibility, but, the real world doesn't change, you still have to know and understand the worlds best de-icing system. Never put your airplane in a situation where 'strait ahead and level' while accumulating ice is a requirement to stay alive. Always cross the rocks on top, or between layers, at an altitude your airplane can maintain with one fan shut down. You only intentially fly into an accumulation layer where 'strait ahead down to freezing level' is an option, or the worst case is, 'turn around, strait back, down to freezing level' is the alternate option. If picking and choosing routes that allow this option is not possible, even the airplane 'certified' for known ice stays parked on the ground.
I learned the freezing level lesson one dark evening in october, during the early 80's, on the booth arrival to vancouver in a lightly loaded chieftan. You never want to see the altimeter unwind to below MOCA with throttles pushed to max and blue line speed set on the dial. I've been there, done that, once, and lived to tell about it. It's never going to happen to me again. I fly a light twin on the west coast where we see a lot of ice in the winter, and I'm comfortable knowing that as long as 'find the rain back' is an option, we can safely navigate thru the accumulation layers.
I know, this is a LONG rant, but, the crux of it all is this. 'Certified for known ice' does NOT mean 'Certified for stupid'. What it does mean, is, more flight planning options, and, a real need to know and understand ice on airframes if you intend to use those options. In other parts of the country, things may well be different, but here on the west coast, knowing and understanding freezing levels is the key to safely operating in these conditions. No money in the world can buy the comfort of 'rain' for an iced up airframe. Leave yourself the 'directly back to the rain' option always open, and, you will live to fight another day. Close that option, and one day, the rocks may well reach up and swat you out of the sky.
Re: Known Icing Aircraft
And very much appreciated. I was hoping you would post on this thread, as I have seen some of your previous posts re icing. I have followed your advice on this subject in the past, and have been extremely glad that I did.I know, this is a LONG rant
Thanks.
Wahunga!
Re: Known Icing Aircraft
Great post by GE, who has been there, and done that
(icing in a bugsmasher).
However, the following just goes to show the incredible
variation in geography in Canada:
rule in central Canada, you would never, ever fly in the
winter, because the freezing level is always at (below)
the surface.
The important thing for newbies to take away from this
discussion, is note how GE negotiated with both ATC and
Enforcement. If you simply do what you are told to do,
you will surely end up dead, dead, dead.
Please don't plan to fly through "moderate" icing in
a bugsmasher. But if you get hooped, and end up
having to descend through one, note the techniques
that GE used. Don't ever, ever accept a clearance
which requires you to level off in moderate icing,
no matter how convenient it would be for ATC.
(icing in a bugsmasher).
However, the following just goes to show the incredible
variation in geography in Canada:
That may be the case in Vancouver, but if you applied thatWhen flying in potential icing conditions, we climb thru the ice only in areas where the MEA below us, is well below the freezing level
rule in central Canada, you would never, ever fly in the
winter, because the freezing level is always at (below)
the surface.
The important thing for newbies to take away from this
discussion, is note how GE negotiated with both ATC and
Enforcement. If you simply do what you are told to do,
you will surely end up dead, dead, dead.
Please don't plan to fly through "moderate" icing in
a bugsmasher. But if you get hooped, and end up
having to descend through one, note the techniques
that GE used. Don't ever, ever accept a clearance
which requires you to level off in moderate icing,
no matter how convenient it would be for ATC.
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Re: Known Icing Aircraft
Headley,
Does the 421 have Automatic aux air doors or manual?
Years ago we iced up real fast and real bad in 404 with manual air doors. Both engines went to idle and we plummited 8500 ft turned upside down completely out of control barely recovering above the ground at night on the dials... I still have nightmares
I only ask because some Cessna turbocharged engines come with automatic aux air doors and some don't. Why don't they all come with the automatic feature?
Does the 421 have Automatic aux air doors or manual?
Years ago we iced up real fast and real bad in 404 with manual air doors. Both engines went to idle and we plummited 8500 ft turned upside down completely out of control barely recovering above the ground at night on the dials... I still have nightmares
I only ask because some Cessna turbocharged engines come with automatic aux air doors and some don't. Why don't they all come with the automatic feature?
