High Alt Icing

form810

Mandate my ass! It's a movie, not a life.
Anyone ever gotten wing icing at FL450?

I recently did. Over the ITCZ. Weird. Just really weird. I oft turn on engine heaters flying through upper level ice crystals (see AF447), but I've never before accumulated wing ice up there. I already had the engines on during this evolution, but I ended up turning ALL the heaters on. First time. It was disorienting and unnerving. I feel like I lost some kind of virginity.

Discuss.
 
This statement confuses me.
High Alt ice crystals can severely mess with your PT probes. I guess it might depend on your type, but it seems in most jets the PT probes are heated as a function of the "engine heat" switch.
 
High Alt ice crystals can severely mess with your PT probes. I guess it might depend on your type, but it seems in most jets the PT probes are heated as a function of the "engine heat" switch.

Must be business jet thing. Every plane I've flown has probes that are automatic with weight off wheels. The engine anti ice switches just control the engine anti ice (and maybe ignitors). But if you meant you hit the switch because it heats the probes I get it... although I'm kind of surprised they aren't already doing their thing.
 
Must be business jet thing. Every plane I've flown has probes that are automatic with weight off wheels. The engine anti ice switches just control the engine anti ice (and maybe ignitors). But if you meant you hit the switch because it heats the probes I get it... although I'm kind of surprised they aren't already doing their thing.
Yeah, I wondered about that. That's precisely why I phrased it the way I did. I've never flown big airline iron. In lots of biz jets, the probe heat comes on with the engine heat switch (which must be deliberately switched ON). When switch ON, you get bleed air to the intake and electric heat to the probes. When OFF, no heat either place. It's not perfect, that's for sure, but getting heat to the PT probes is much like getting heat to the pitot tubes in many A/C. You've got to turn the switch ON.

Despite that tech digression, have you ever experienced wing ice way up in the high flight levels?? That was different in my experience.
 
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Despite that tech digression, have you ever experienced wing ice way up in the high flight levels?? That was different in my experience.

I have gotten ice crystals in the high 30s a few times crossing the ITCZ. Never gotten any ice build up though.
 
I have gotten ice crystals in the high 30s a few times crossing the ITCZ. Never gotten any ice build up though.
Sound like my previous experience. That's what was so weird about this encounter. Wing ice... at FL450!! WTH?
 
Not really "high altitude" icing per se, but I do remember a flight over the Med sea during one early spring at maybe FL250-300, where a bunch of us got engine inlet ice cautions on a completely CAVU day. No real way to have determined if the cautions were valid, but this was maybe 7-8 aircraft in the same area at the same time, so I imagine it was.

*yes I realize you probably are talking to the weirdness of icing at that type of SAT, but icing is weird, and has no friends.
 
Not really "high altitude" icing per se, but I do remember a flight over the Med sea during one early spring at maybe FL250-300, where a bunch of us got engine inlet ice cautions on a completely CAVU day. No real way to have determined if the cautions were valid, but this was maybe 7-8 aircraft in the same area at the same time, so I imagine it was.

*yes I realize you probably are talking to the weirdness of icing at that type of SAT, but icing is weird, and has no friends.
I saw a very similar deal about 20 years ago in a CRJ. Cavu at FL280. Visually verified 3/8ths - 1/2 inch ice build up on inlet leading edges. Strange. Still, it seems a bit more understandable at lower flight levels. Just weird to be getting it at -69°C.
 
Yeah, I wondered about that. That's precisely why I phrased it the way I did. I've never flown big airline iron. In lots of biz jets, the probe heat comes on with the engine heat switch (which must be deliberately switched ON). When switch ON, you get bleed air to the intake and electric heat to the probes. When OFF, no heat either place. It's not perfect, that's for sure, but getting heat to the PT probes is much like getting heat to the pitot tubes in many A/C. You've got to turn the switch ON.

Despite that tech digression, have you ever experienced wing ice way up in the high flight levels?? That was different in my experience.

Are you referring to the pitot tubes or the T2 probe that is in the engine inlet? My memory is a little fuzzy on some of my types, but the last 3 all have specific probe (pitot/static) heat switches. Their coming on had nothing to do with the engine heats, though I do believe the T2 probe was heated only with the cowl anti ice selected.
 
In every airplane Ive flown, if pitot heats weren't automatic they were turned on just prior to taking the runway for takeoff usually along with windshield heat.
 
I've noticed that if an aircraft is really dusty, it picks up ice where normally it wouldn't. Higher and colder temps the ice will stick. Condensation nuclei or some fancy word like that.

Happened at bit when I parked at PSP for a few days rotting in some hotel waiting on golfers.
 
I've noticed that if an aircraft is really dusty, it picks up ice where normally it wouldn't. Higher and colder temps the ice will stick. Condensation nuclei or some fancy word like that.

Happened at bit when I parked at PSP for a few days rotting in some hotel waiting on golfers.
If you're spending your time in Palm Springs rotting in a hotel, you were doing it wrong. :cool:
 
Never seen that. OAT temps below -40 we don't use anti-ice, never had a problem.
beat me to it...there is a reason why this number is used...it's never been observed below that temp thus the anti-ice for the engines/wings
 
Are you referring to the pitot tubes or the T2 probe that is in the engine inlet? My memory is a little fuzzy on some of my types, but the last 3 all have specific probe (pitot/static) heat switches. Their coming on had nothing to do with the engine heats, though I do believe the T2 probe was heated only with the cowl anti ice selected.
Negative. Not Pitot tubes. The T2P2 probes. The little ones that measure temps/pressures at the inlet. They hang out in front of the fan.
 
Never seen that. OAT temps below -40 we don't use anti-ice, never had a problem.
Yeah, me neither. That's precisely why I'm asking. It was truly weird Wx. Clouds -at 450- were so thick you could barely see the wings out the windows.
 
We were in a CJ3 and had a thick layer of ice build-up at FL430 through the top of a cloud we couldn't get around at our TOD. The problem was it was too cold to pop the boots on the tail.

As for the engine probes, I know the Hawker 800 and the Challenger 604 both need the cowl heat on to heat the T2 probes.
 
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