Icing
11-19-2008 | 04:52 PM
#11
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From: Left Seat PA31-350
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 by the NTSB in cases to define "known icing conditions". Even though the AIM is not regulatory, it has a tendency at times to become regulatory in hearings.
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.
If the briefer gives you an AIRMET for forecast moderate icing and you cannot stay clear of clouds and clear of precipitation, then no, takeoff would be prohibited.
Here's the FAA advisory circular on icing:
http://rgl.faa.gov/Regulatory_and_Gu...C%2091-74A.pdf
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.
If the briefer gives you an AIRMET for forecast moderate icing and you cannot stay clear of clouds and clear of precipitation, then no, takeoff would be prohibited.
Here's the FAA advisory circular on icing:
http://rgl.faa.gov/Regulatory_and_Gu...C%2091-74A.pdf
11-19-2008 | 06:41 PM
#12
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From: 737/FO
aahhgg! You are correct. I'm out on a trip and just did a search of the FAA regs database and didn't check the section. I remember that reg from my corporate days. However, I have read something else. I will have to find it. In the meantime I'll edit my first post...
Ok. Here is the info from the advisory circular from a regulatory point-of-view for general part 91 operation:
"d. Aircraft Not Certificated for Flight in Icing Conditions.
(1) Aircraft certificated since the mid-1970s that are not certificated for flight in icing conditions will have a limitation in the AFM or POH and possibly a placard on the aircraft stating that flight into “known icing conditions” is prohibited. “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. Such limitations are binding under § 91.9, Civil aircraft flight manual, marking, and placard requirements, and this regulation takes precedence over §§ 91.527 and 135.227. However, if a pilot of such an airplane were to takeoff and fly in area in which icing is forecast (e.g., AIRMET Zulu), it is expected the pilot will through preflight planning and in-flight execution:
(a) First attempt to avoid areas of “potential icing conditions”, which are areas of visible moisture such as clouds at temperatures below freezing;
(b) If that is not practical, attempt to avoid areas of forecast icing by all tools available (e.g., AIRMETs, SIGMETs, CIP and FIP); and
(c) If icing is encountered, declare an emergency and exit the conditions immediately.
NOTE: Failure to follow the section above may result in enforcement action under § 91.103, Preflight action, or § 91.13, Careless or reckless operation, depending on the circumstances and the actions a reasonable pilot will take."
As stated above AC 91-74A is a good read.
Ok. Here is the info from the advisory circular from a regulatory point-of-view for general part 91 operation:
"d. Aircraft Not Certificated for Flight in Icing Conditions.
(1) Aircraft certificated since the mid-1970s that are not certificated for flight in icing conditions will have a limitation in the AFM or POH and possibly a placard on the aircraft stating that flight into “known icing conditions” is prohibited. “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. Such limitations are binding under § 91.9, Civil aircraft flight manual, marking, and placard requirements, and this regulation takes precedence over §§ 91.527 and 135.227. However, if a pilot of such an airplane were to takeoff and fly in area in which icing is forecast (e.g., AIRMET Zulu), it is expected the pilot will through preflight planning and in-flight execution:
(a) First attempt to avoid areas of “potential icing conditions”, which are areas of visible moisture such as clouds at temperatures below freezing;
(b) If that is not practical, attempt to avoid areas of forecast icing by all tools available (e.g., AIRMETs, SIGMETs, CIP and FIP); and
(c) If icing is encountered, declare an emergency and exit the conditions immediately.
NOTE: Failure to follow the section above may result in enforcement action under § 91.103, Preflight action, or § 91.13, Careless or reckless operation, depending on the circumstances and the actions a reasonable pilot will take."
As stated above AC 91-74A is a good read.
Last edited by WEACLRS; 11-19-2008 at 07:04 PM.
11-19-2008 | 07:37 PM
#13
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From: CFII
In regards to the spirit of the thread...... I have made a personal choice never to fly my un-equipped aircraft intentinally into visible precipitation when the temp is close to freezing or below. That obviously limits my winter GA flying. However, I was trying to gain a technical/legal understanding of what is or is not legal in the eyes of the FAA regarding unequipped aircaft flying in known/forecast icing conditions.
I obviously understand you can't legally fly into known icing conditions. One of my problems is I cant nail down a definition of known icing conditions. I realized just now as Im typing perhaps my hangup rests in bowersbum's post. The NTSB has in some cases to the best of my knowledge used, the AIM 7-1-21 (b) (im using an 08 version so that might be the difference between browersbum's AIM (7-1-22 b) to define known icing conditions. If that is true I would have to be prudent and just use the more restrictive definition. Which would compliment my decision to not fly in cold clouds/visible precip.
I obviously understand you can't legally fly into known icing conditions. One of my problems is I cant nail down a definition of known icing conditions. I realized just now as Im typing perhaps my hangup rests in bowersbum's post. The NTSB has in some cases to the best of my knowledge used, the AIM 7-1-21 (b) (im using an 08 version so that might be the difference between browersbum's AIM (7-1-22 b) to define known icing conditions. If that is true I would have to be prudent and just use the more restrictive definition. Which would compliment my decision to not fly in cold clouds/visible precip.
11-19-2008 | 07:50 PM
#14
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From: CFII
ok, so in my own head, I can live with what I believe to be the NTSB's definiton/interpertation of known icing.... temps 2 to -10 in visiable moisture. My next question involves flying that same unequipped aircraft on a precipitation free day clear of clouds while an icing airmet is issued for surface to 10 covering all of michigan (where i fly). Can I legally fly? Just the other day Im looking outside at scattered clouds 4000-5000, while an icing airmet is out for surface to 10. Am I legal to fly? If not there certainly are a lot of illegals flying around 
I know GA flying is limited to some extent in the winter but If I cant fly with an icing airmet out, while staying clear of clouds/moisture, I cant fly in the winter period. Theres always an airmet covering michigan in the winter! All responses, apprecitiated as always.
I know GA flying is limited to some extent in the winter but If I cant fly with an icing airmet out, while staying clear of clouds/moisture, I cant fly in the winter period. Theres always an airmet covering michigan in the winter! All responses, apprecitiated as always.
11-19-2008 | 08:03 PM
#15
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From: CFII
aahhgg! You are correct. I'm out on a trip and just did a search of the FAA regs database and didn't check the section. I remember that reg from my corporate days. However, I have read something else. I will have to find it. In the meantime I'll edit my first post...
Ok. Here is the info from the advisory circular from a regulatory point-of-view for general part 91 operation:
"d. Aircraft Not Certificated for Flight in Icing Conditions.
(1) Aircraft certificated since the mid-1970s that are not certificated for flight in icing conditions will have a limitation in the AFM or POH and possibly a placard on the aircraft stating that flight into “known icing conditions” is prohibited. “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. Such limitations are binding under § 91.9, Civil aircraft flight manual, marking, and placard requirements, and this regulation takes precedence over §§ 91.527 and 135.227. However, if a pilot of such an airplane were to takeoff and fly in area in which icing is forecast (e.g., AIRMET Zulu), it is expected the pilot will through preflight planning and in-flight execution:
(a) First attempt to avoid areas of “potential icing conditions”, which are areas of visible moisture such as clouds at temperatures below freezing;
(b) If that is not practical, attempt to avoid areas of forecast icing by all tools available (e.g., AIRMETs, SIGMETs, CIP and FIP); and
(c) If icing is encountered, declare an emergency and exit the conditions immediately.
NOTE: Failure to follow the section above may result in enforcement action under § 91.103, Preflight action, or § 91.13, Careless or reckless operation, depending on the circumstances and the actions a reasonable pilot will take."
As stated above AC 91-74A is a good read.
Ok. Here is the info from the advisory circular from a regulatory point-of-view for general part 91 operation:
"d. Aircraft Not Certificated for Flight in Icing Conditions.
(1) Aircraft certificated since the mid-1970s that are not certificated for flight in icing conditions will have a limitation in the AFM or POH and possibly a placard on the aircraft stating that flight into “known icing conditions” is prohibited. “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. Such limitations are binding under § 91.9, Civil aircraft flight manual, marking, and placard requirements, and this regulation takes precedence over §§ 91.527 and 135.227. However, if a pilot of such an airplane were to takeoff and fly in area in which icing is forecast (e.g., AIRMET Zulu), it is expected the pilot will through preflight planning and in-flight execution:
(a) First attempt to avoid areas of “potential icing conditions”, which are areas of visible moisture such as clouds at temperatures below freezing;
(b) If that is not practical, attempt to avoid areas of forecast icing by all tools available (e.g., AIRMETs, SIGMETs, CIP and FIP); and
(c) If icing is encountered, declare an emergency and exit the conditions immediately.
NOTE: Failure to follow the section above may result in enforcement action under § 91.103, Preflight action, or § 91.13, Careless or reckless operation, depending on the circumstances and the actions a reasonable pilot will take."
As stated above AC 91-74A is a good read.
So if I'm reading that right and follow step A. I can fly clear of clouds and visible moisture temp below 2 - -10 with an airmet in effect, right?
11-19-2008 | 08:17 PM
#16
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From: CFII
ok I think this is the last what-if... Im now flying clear of visible moisture in a temp of 2 to -10 with an airmet in effect. So far, I believe this to be legal. Im flying Lansing to Grand Rapids. Grand Rapids has a TAF out forecasting light snow showers and I land there. Was that just a forecast icing condition i just landed in and in doing so did I just violate the AC bowersbum posted (paragraph b)
11-19-2008 | 08:26 PM
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11-19-2008 | 09:50 PM
#18
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From: Legacy FO
AC No: 91-74A
Part 91 Icing Regulations.
a.
IFR. No pilot may fly an airplane under IFR into known or forecast moderate icing conditions unless one or more of the following apply:
(1)
The aircraft has ice protection provisions that meet the requirements in 14 CFR part 135, appendix A, paragraph 34 of Special Federal Aviation Regulation (SFAR) No. 23.
(2)
The aircraft has ice protection provisions that meet the requirements for transport category airplane type certification.
(3)
The aircraft has functioning deicing or anti-icing equipment protecting each propeller, windshield, wing, stabilizing surface, control surface, airspeed instrument, altimeter, rate of climb instrument, and flight attitude instrument system.
b.
VFR. No pilot may fly an airplane under VFR into known light or moderate icing conditions unless one or more of the following apply:
(1)
The aircraft has ice protection provisions that meet the requirements in SFAR 23 paragraph 34 (same as part 135, appendix A, paragraph 34, and § 23.1419 at Amendment 23-14).
(2)
The aircraft has ice protection provisions that meet the requirements for transport category airplane type certification.
(3)
The aircraft has functioning deicing or anti-icing equipment protecting each propeller, windshield, wing, stabilizing surface vertical tail, control surface flap, aileron, elevator, airspeed instrument, altimeter, rate of climb instrument, and flight attitude instrument system.
To answer the OP's question, Can I legally fly into a cloud with an OAT of -3?
Based on the AC 91-74A, YES, but only if the icing wasn't forecasted or known to be moderate (AIRMET) and you filed IFR. If you filed VFR, well, you're in violation as soon as you flew into the clouds.
But, as some have mentioned, and the author of the book I first quoted suggested, according to many FAA and NTSB reports, the FAA has drawn a very fine line between KNOWN and FORECASTED ICING.
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) If you filed IFR, NO. You can't fly into an area of known or forecasted icing. VFR, yes, if you obey cloud clearance requirements for the specific class of airspace.
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?
If they were filed VFR, yes. IFR, maybe (was there forecasted or known reports of icing).
DISCLAIMER ... this is the best I could come up with. I'm sure there are others that are smarter than me or have better gouge. The above references came from the AC No: 91-74A circular.
a.
IFR. No pilot may fly an airplane under IFR into known or forecast moderate icing conditions unless one or more of the following apply:
(1)
The aircraft has ice protection provisions that meet the requirements in 14 CFR part 135, appendix A, paragraph 34 of Special Federal Aviation Regulation (SFAR) No. 23.
(2)
The aircraft has ice protection provisions that meet the requirements for transport category airplane type certification.
(3)
The aircraft has functioning deicing or anti-icing equipment protecting each propeller, windshield, wing, stabilizing surface, control surface, airspeed instrument, altimeter, rate of climb instrument, and flight attitude instrument system.
b.
VFR. No pilot may fly an airplane under VFR into known light or moderate icing conditions unless one or more of the following apply:
(1)
The aircraft has ice protection provisions that meet the requirements in SFAR 23 paragraph 34 (same as part 135, appendix A, paragraph 34, and § 23.1419 at Amendment 23-14).
(2)
The aircraft has ice protection provisions that meet the requirements for transport category airplane type certification.
(3)
The aircraft has functioning deicing or anti-icing equipment protecting each propeller, windshield, wing, stabilizing surface vertical tail, control surface flap, aileron, elevator, airspeed instrument, altimeter, rate of climb instrument, and flight attitude instrument system.
To answer the OP's question, Can I legally fly into a cloud with an OAT of -3?
Based on the AC 91-74A, YES, but only if the icing wasn't forecasted or known to be moderate (AIRMET) and you filed IFR. If you filed VFR, well, you're in violation as soon as you flew into the clouds.
But, as some have mentioned, and the author of the book I first quoted suggested, according to many FAA and NTSB reports, the FAA has drawn a very fine line between KNOWN and FORECASTED ICING.
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) If you filed IFR, NO. You can't fly into an area of known or forecasted icing. VFR, yes, if you obey cloud clearance requirements for the specific class of airspace.
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?
If they were filed VFR, yes. IFR, maybe (was there forecasted or known reports of icing).
DISCLAIMER ... this is the best I could come up with. I'm sure there are others that are smarter than me or have better gouge. The above references came from the AC No: 91-74A circular.
11-19-2008 | 09:54 PM
#19
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From: UPS 757/767 Capt ONT
"If you filed VFR, well, you're in violation as soon as you flew into the clouds."
Well, if your filed VFR and fly in the clouds, you got bigger problems with the FAA than possibly running into ice....
I think the VFR subparagraph has more to do with flying under freezing rain in VMC or something like that.
Well, if your filed VFR and fly in the clouds, you got bigger problems with the FAA than possibly running into ice....
I think the VFR subparagraph has more to do with flying under freezing rain in VMC or something like that.
11-20-2008 | 04:18 AM
#20
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sellener, I think you are being way too literal, although a lot of that is the FAA's fault i the way it defines "known ice". But, no, you are not going to encounter ice in visual conditions, even if there is an Airmet for icing in clouds and in precipitation.
The FAA's AC is giving you a set of guidelines and examples of the types of conditions that are conducive to icing. The only significant one outside of clouds is freezing rain (although snow might be an issue in limited circumstances).
The legal standard for violations is even looser - if you flew into conditions that a pilot should have known knew was conducive to icing conditions - even if there was no PIREP for the immediate area or specific icing forecast - you can be found in violation.
Here's an example of how loose the standard can be: http://ntsb.gov/alj/alj/O_n_O/docs/aviation/5154.PDF
A violation often comes down to: if you land with ice on your wings or cause a problem because you actually encounter ice, the chances are you flew into known icing conditions.
The FAA's AC is giving you a set of guidelines and examples of the types of conditions that are conducive to icing. The only significant one outside of clouds is freezing rain (although snow might be an issue in limited circumstances).
The legal standard for violations is even looser - if you flew into conditions that a pilot should have known knew was conducive to icing conditions - even if there was no PIREP for the immediate area or specific icing forecast - you can be found in violation.
Here's an example of how loose the standard can be: http://ntsb.gov/alj/alj/O_n_O/docs/aviation/5154.PDF
A violation often comes down to: if you land with ice on your wings or cause a problem because you actually encounter ice, the chances are you flew into known icing conditions.
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