Icing
11-19-2008, 06:57 AM
#1
Gets Weekends Off
Thread Starter
Joined APC: Jul 2008
Position: CFII
Posts: 139
Icing
I am a low time private/insturment pilot, commercial student. I have scowered forums, and NTSB rulings, and dont have a good idea of how to apply the definitinos of "known icing conditions" or "forecast icing conditions." My question pertains to GA winter flying.
Also if there are multiple threads on this topic already please simply direct me there. I didnt see them while using the search for APC.
so some questions (all pertain to a GA aircraft with simply pitot heat):
1) Can I legally fly into a cloud with an OAT of -3? (some NTSB rulings seem to use this condition as known icing conditions)
2) Can I takeoff with an icing airmet surface to 10000. (ceiling off say 7000 with no precipitation in the forecast if I stay VFR)
a) if I do and it starts to precip, am I now open to scrutiny if something would happen?
(icing airmet and visible moisture)
3) I see pireps from c-172's (assumed not certified for Flight into Icing) reporting rime icing with freezing OAT. Are they reporting that they are in violation?
Also if there are multiple threads on this topic already please simply direct me there. I didnt see them while using the search for APC.
so some questions (all pertain to a GA aircraft with simply pitot heat):
1) Can I legally fly into a cloud with an OAT of -3? (some NTSB rulings seem to use this condition as known icing conditions)
2) Can I takeoff with an icing airmet surface to 10000. (ceiling off say 7000 with no precipitation in the forecast if I stay VFR)
a) if I do and it starts to precip, am I now open to scrutiny if something would happen?
(icing airmet and visible moisture)
3) I see pireps from c-172's (assumed not certified for Flight into Icing) reporting rime icing with freezing OAT. Are they reporting that they are in violation?
11-19-2008, 08:09 AM
#3
Prime Minister/Moderator
Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,253
DISCLAIMER: There is a big difference between legal and safe as far as this topic goes. I'm going to discuss legal, which is often NOT safe.
Forecast icing is not "Known Icing"...legally you can fly into that area (not a good idea of course).
Environmental conditions such as a certain temperature have never counted as "known icing" to my knowledge...even in the airline biz temp/moisture combinations are referred to as "conditions conducive to icing".
The gold-standard definition of known icing is actual ice observed at the flight altitude...this almost always requires a PIREP. A METAR from a nearby mountain top observatory, or a freezing rain report on the ground would qualify also. Again it has to be actual ice reported (of any type), not moisture/temp.
Also if YOU encounter icing in flight, then that immedaitely becomes "known icing" and you need to get out of it (obviously).
EDIT: Looks like Fatty and I have different answers on this one...I'll do some research if I have time. His answer is definately the safest answer, if not the legal answer. Also the FAA could charge you with violating 91.13 if you do anything which they don't think was a great idea...even if it is not a violation of other regs.
Forecast icing is not "Known Icing"...legally you can fly into that area (not a good idea of course).
Environmental conditions such as a certain temperature have never counted as "known icing" to my knowledge...even in the airline biz temp/moisture combinations are referred to as "conditions conducive to icing".
The gold-standard definition of known icing is actual ice observed at the flight altitude...this almost always requires a PIREP. A METAR from a nearby mountain top observatory, or a freezing rain report on the ground would qualify also. Again it has to be actual ice reported (of any type), not moisture/temp.
Also if YOU encounter icing in flight, then that immedaitely becomes "known icing" and you need to get out of it (obviously).
EDIT: Looks like Fatty and I have different answers on this one...I'll do some research if I have time. His answer is definately the safest answer, if not the legal answer. Also the FAA could charge you with violating 91.13 if you do anything which they don't think was a great idea...even if it is not a violation of other regs.
11-19-2008, 08:10 AM
#4
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Joined APC: Mar 2008
Position: FAA 'Flight Check'
Posts: 13,837
Originally Posted by KC10 FATboy
Taken from "Everything Explained for the Professional Pilot"
Ice is found in visible moisture between +5 and -20 degrees C or colder -- but usually between +2 and -10 degrees C.
Any mention of icing conditions during a weather briefing, even if only a "slight possibility" is considered "Known icing" by the FAA and the NTSB. The briefer should check AIRMETs -- issued at the first indication of moderate ice; and SIGMETs -- issued for severe icing. Flight into known icing is definitely forbidden unless the aircraft is certificated for these conditions.
You might want to mention to the briefer that you plan to remain below the freezing level and/or clear of clouds. This might allow them to remove the "known icing conditions" from your brief, which would allow you to takeoff. However, if you encountered ice and caused some sort of problem, you're probably going to hear from the FAA.
References; Part 23, 25, 91.9, 91.13, 91.527, 121.341, 121.629, 125.221, 135.227, 135.345, AIM 7-1-19, 7-1-22, 7-1-23, Advisory Circulars 20-73, 23.1419-1, 135-9, AFM or POH
-Fatty
Ice is found in visible moisture between +5 and -20 degrees C or colder -- but usually between +2 and -10 degrees C.
Any mention of icing conditions during a weather briefing, even if only a "slight possibility" is considered "Known icing" by the FAA and the NTSB. The briefer should check AIRMETs -- issued at the first indication of moderate ice; and SIGMETs -- issued for severe icing. Flight into known icing is definitely forbidden unless the aircraft is certificated for these conditions.
You might want to mention to the briefer that you plan to remain below the freezing level and/or clear of clouds. This might allow them to remove the "known icing conditions" from your brief, which would allow you to takeoff. However, if you encountered ice and caused some sort of problem, you're probably going to hear from the FAA.
References; Part 23, 25, 91.9, 91.13, 91.527, 121.341, 121.629, 125.221, 135.227, 135.345, AIM 7-1-19, 7-1-22, 7-1-23, Advisory Circulars 20-73, 23.1419-1, 135-9, AFM or POH
-Fatty
It sounds like you're (or the book really) is saying that you couldn't fly on a clear, cold day is the temperature fell inside the range above; or are you saying that he could not fly into clouds under those conditions (which I would understand). If in a temperature range that supports the formation of ice and visible moisture is regarded as "known icing", what constitues "forecasted icing"? The temperature is expected to fall to something within the range and clouds are expected to form?
Good questions sellener. I look forward to hearing the information provided by our smart group here on the forum.
USMCFLYR
11-19-2008, 10:58 AM
#5
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Joined APC: Jan 2006
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The AIM in 7-1-22 (b) states "A pilot can expect icing when flying in visible precipitation, such as rain or cloud droplets, and the temperature is between +02 and -10 degrees Celsius..." This definition has been used in NTSB and court cases to define "known icing conditions". Even though the AIM is not regulatory, it has a tendency at times to become regulatory in hearings. You can also check 7-1-23 in the AIM for the FAA's definition of known and potential icing conditions.
EDIT: This applies to subpart F of Part 91 - Large and Turbine Powered Multiengine Airplanes: This leads to the FAR under part 91, 91.527 Operating in icing conditions. 91.527 (b) says no pilot may fly under IFR conditions into known or forecast moderate icing conditions or under VFR into known light or moderate icing conditions unless the aircraft has the appropriate de-icing and/or anti-icing protection equipment and is certified for icing conditions. 91.527 (c) basically says you can't fly into known or forecast severe icing conditions unless the aircraft has appropriate equipment and is certified.
I will do a search of the NTSB and FAA sites to see how they have applied the regs. I thought there was a reg somewhere other than 91.13 about not flying an aircraft other than in accordance with it's operating limitations...
Here's the FAA advisory circular on icing:
http://rgl.faa.gov/Regulatory_and_Gu...C%2091-74A.pdf
EDIT: This applies to subpart F of Part 91 - Large and Turbine Powered Multiengine Airplanes: This leads to the FAR under part 91, 91.527 Operating in icing conditions. 91.527 (b) says no pilot may fly under IFR conditions into known or forecast moderate icing conditions or under VFR into known light or moderate icing conditions unless the aircraft has the appropriate de-icing and/or anti-icing protection equipment and is certified for icing conditions. 91.527 (c) basically says you can't fly into known or forecast severe icing conditions unless the aircraft has appropriate equipment and is certified.
I will do a search of the NTSB and FAA sites to see how they have applied the regs. I thought there was a reg somewhere other than 91.13 about not flying an aircraft other than in accordance with it's operating limitations...
Here's the FAA advisory circular on icing:
http://rgl.faa.gov/Regulatory_and_Gu...C%2091-74A.pdf
Last edited by WEACLRS; 11-19-2008 at 07:12 PM.
11-19-2008, 11:24 AM
#6
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As a sidenote way back when I flew checks in 210's with boots, the forecasters would predict light to moderate icing in the clouds anytime the temp was 32 or colder. There were very few times icing was actually encountered so I'm sure the forecasters were just covering thier dupa. If we didn't take off because of a forecast of ice we would have never flown IFR in the winter.
Another note. I remember holding @ Bojak @ 3000 going into MDW waiting for the runways to be cleared. Never picked up any ice. I was the first one in before the 737's. When I landed I was asked for a braking report and said "fair to good". It was actually pretty good but I didn't want to be responsible for a bigger bird having problems braking.
When I got on the ground nobody was taking off and I had over 1/8 inch clear ice all over the plane before finishing taxiing in. Um, temp inversion????
Another note. I remember holding @ Bojak @ 3000 going into MDW waiting for the runways to be cleared. Never picked up any ice. I was the first one in before the 737's. When I landed I was asked for a braking report and said "fair to good". It was actually pretty good but I didn't want to be responsible for a bigger bird having problems braking.
When I got on the ground nobody was taking off and I had over 1/8 inch clear ice all over the plane before finishing taxiing in. Um, temp inversion????
11-19-2008, 12:04 PM
#8
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Joined APC: Jun 2008
Posts: 2,930
Pirep is the best option for knowing if there is ice. If I look at winds aloft and see -01, I would still go flying because it's not really accurate. If the control tower says that a person reports icing or a pirep reports icing, then I won't go flying.
11-19-2008, 03:20 PM
#9
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Position: UPS 757/767 Capt ONT
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From the ice AC listed above:
"Forecast Icing Conditions. Environmental conditions expected by a NWS or an FAA-approved weather provider to be conducive to the formation of in-flight icing on aircraft.
“Known icing conditions,” as defined in the AIM, are conditions in which ice is observed or detected in flight, by your aircraft or another aircraft, or an airport."
Since the AC is put out by the FAA, and not some guy who wrote a book, I'd tend to lend it more credibility. That AC had some good stuff in it. Anyone who pilots light aircraft in the winter should be familiar with it.
"Forecast Icing Conditions. Environmental conditions expected by a NWS or an FAA-approved weather provider to be conducive to the formation of in-flight icing on aircraft.
“Known icing conditions,” as defined in the AIM, are conditions in which ice is observed or detected in flight, by your aircraft or another aircraft, or an airport."
Since the AC is put out by the FAA, and not some guy who wrote a book, I'd tend to lend it more credibility. That AC had some good stuff in it. Anyone who pilots light aircraft in the winter should be familiar with it.
11-19-2008, 03:53 PM
#10
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I guess I'm trying to figure out the spirit of this thread. Does the OP want to go up during the winter and get some actual instrument time. Again there are differences like rickair states between legal and safe.
I operated non-icing aircraft in the winter for many years instructing. There was no reason to go out on a hard IFR day when it was below freezing hence the visible moisture and below freezing temps made a pretty good recipe for picking up icing. Now that didn't bar me from getting my students actual IFR experience. All I needed was weather that would allow me a way out - ceilings higher than MVA, MEA. In which case I would file a block of airspace with an block of altitude that would allow me to enter and exit the clouds at my leisure. Hop up in the clouds, get no ice, great. Start picking up a slightest amount get out quickly and easily. I had this discussion with our FSDO rep and he had no problem with this.
Again I don't know for sure what the OP wants out of these questions but there are very few legal and very few safe ways to get actual IFR in the winter in a not certified for icing aircraft.
I operated non-icing aircraft in the winter for many years instructing. There was no reason to go out on a hard IFR day when it was below freezing hence the visible moisture and below freezing temps made a pretty good recipe for picking up icing. Now that didn't bar me from getting my students actual IFR experience. All I needed was weather that would allow me a way out - ceilings higher than MVA, MEA. In which case I would file a block of airspace with an block of altitude that would allow me to enter and exit the clouds at my leisure. Hop up in the clouds, get no ice, great. Start picking up a slightest amount get out quickly and easily. I had this discussion with our FSDO rep and he had no problem with this.
Again I don't know for sure what the OP wants out of these questions but there are very few legal and very few safe ways to get actual IFR in the winter in a not certified for icing aircraft.
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