Appendix 3
(6) During flight, monitor engine RPM. A drop in RPM or manifold pressure may indicate induction icing. Apply carburetor heat or alternate air if required.
(7) If ice is encountered in-flight, exit the conditions immediately.
(8) Use visual cues to identify ice formation. If ice forms on the wing, there is a possibility the tail may be accumulating ice as well.
(9) Stay alert for any performance or handling degradation that may be an indicator of ice accumulation.
(10) Remember that recovery procedures from an ice-induced tailplane stall are opposite from those for an ice-induced wing stall.
(11) If using an autopilot, when workload permits, periodically disengage and manually fly the aircraft to identify possible handling changes or control jamming caused by ice.
c. Approach and Landing.
(1) Be prepared for unexpected attitude changes when changing the airplane’s configuration. If the aircraft’s performance characteristics change suddenly, return to the previous configuration.
(2) If landing with an accumulation of ice on the tailplane, perform a no-flap landing at a higher approach speed. Use a longer runway if available.
(3) After touchdown, use brakes sparingly to prevent skidding.
2. Piston Aircraft Certificated or Equipped for Flight in Icing Conditions.
a. Preflight.
(1) Always obtain a thorough preflight weather briefing. Evaluate cloud types, bases, and tops; types of precipitation; freezing levels; and pilot reports.
(2) Pack additional items in your flight bag such as a large flashlight, spare fresh batteries, and transceiver.
(3) During preflight planning, identify alternate airports along the route of flight to be used if unscheduled weather is encountered. Choose airports with longer runways.
(4) Always know how to escape icing conditions (either climb or descend to warmer areas, make a 180 degree turn, etc.).
(5) During the preflight inspection, clean all ice, frost, and snow off the aircraft.
(6) Check that pitot heat and static heat are operable.
Appendix 3
(7) Check pitot/static openings, fuel drains, and stall warning sensors to ensure they are not clogged with ice.
(8) Cycle deicing and anti-icing systems to check for proper operation.
(9) Clear any accumulated ice or snow from brakes and wheel fairings.
(10) Check controls externally for ice/snow binding.
b. Taxi/Takeoff/In-Flight.
(1) Use brakes carefully during taxi to prevent skidding.
(2) Ensure that carburetor heat or alternate air is working.
(3) Check controls for full range of motion.
(4) After takeoff, if recommended by the manufacturer, cycle landing gear to clear snow or slush from wheel wells.
(5) During flight, monitor engine RPM. A drop in RPM or manifold pressure may indicate induction ice. Apply carburetor heat or alternate air if required.
(6) Refer to the AFM or POH for proper operation of anti-icing and deicing systems.
A rule of thumb is that anti-ice systems should be activated at the first sign of visible moisture with air temperatures some margin above freezing. Deicing systems should be activated at the first sign of ice accretion.
(7) Use visual cues to identify ice formation and regularly check for ice accumulation behind protected areas on the aircraft. If ice forms on the wing, there is a possibility that the tail may be accumulating ice as well.
(8) Stay alert for any performance or handling degradation that may be an indicator of ice accumulation.
(9) Remember that recovery procedures from an ice-induced tailplane stall are opposite from those for an ice-induced wing stall.
(10) If using an autopilot, if workload permits, periodically disengage and manually fly the aircraft to identify handling changes caused by airframe icing.
c. Approach and Landing.
(1) Be prepared for unexpected attitude changes when changing the airplane’s configuration. If the aircraft begins to roll or pitch unexpectedly, return to the previous configuration.
(2) If landing with an accumulation of ice, use a higher approach speed. Use a longer runway if available.
Appendix 3
(3) After touchdown, use brakes sparingly to prevent skidding.
3. Turbo-Propeller Aircraft.
a. Preflight.
NOTE: Professional flightcrews flying complex, high performance aircraft should always refer to the AFM or POH and company guidance materials as the authority for procedures for flight into icing conditions.
(1) For ground deicing operations, refer to company manuals, AC 120-58, and AC 135-17 for guidance.
(2) Always obtain a thorough preflight weather briefing. Look for cloud types, bases, and tops; types of precipitation; freezing levels; and pilot reports.
(3) Preflight icing inspections of the aircraft in ground icing conditions are essential.
Tactile inspections are mandatory for some aircraft and are very valuable for detecting clear ice.
By physically touching the surface, any fine contaminants not easily visible can be detected.
Refer to AFM or POH to determine if a tactile inspection is mandatory for your aircraft.
(4) Clean all ice, frost, and snow off of the aircraft
(5) Check that pitot heat and static heat are operable.
(6) Check pitot/static openings, fuel drains, and stall warning sensors to ensure they are not clogged with ice.
(7) Cycle anti-icing and deicing systems to check for proper operation.
(8) Clear any accumulated ice or snow from brakes and wheel fairings.
(9) Inspect the engine inlets of turbine engines and remove any accumulated ice from the nacelle inlet as well as around the nacelle drain hole and around the fan blades.
b. Taxi/Takeoff/In-Flight.
(1) Use brakes carefully during taxi to prevent skidding.
(2) Check controls for full range of motion.
(3) After takeoff, if recommended by the manufacturer, cycle landing gear to clear snow or slush from wheel wells.
(4) Refer to the AFM or POH for proper operation of anti-icing and deicing systems.
A rule of thumb is that anti-ice systems should be activated at the first sign of visible moisture with air temperatures some margin above freezing. Deicing systems should be activated at the first sign of ice accretion.
Appendix 3
(5) Power settings with bleed air on should be set according to the POH or AFM reference section.
(6) For turbine engines, perform regular engine power run-ups to shed accumulated ice while taxiing, per the AFM
(7) Use visual cues to identify ice formation and regularly check for ice accumulation behind protected areas on the aircraft.
(8) Stay alert for ice formations on wings that may cause control problems.
(9) If there is a need to use wing-deicing systems, there is a possibility that the tail may be accumulating ice as well.
(10) Remember that recovery procedures from an ice-induced tailplane stall are opposite from those for an ice-induced wing stall.
(11) If using an autopilot, if workload permits, periodically disengage and manually fly the aircraft to identify handling changes caused by ice. Some pilots have been known to rest their leg against the airplane’s trim wheel to monitor the amount of trim being put in by the autopilot.
(12) Use airspeed bug to monitor changes to airspeed.
c. Approach and Landing.
(1) Be prepared for unexpected attitude changes when changing the airplane’s configuration. If the performance characteristics change suddenly, return to the previous configuration.
(2) Determine if freezing drizzle or freezing rain are being reported and avoid flying into these areas. A ground observation of ice pellets indicates possibly freezing drizzle or rain aloft. A ground observation of any type of precipitation when temperatures are near freezing may indicate freezing precipitation aloft, so be vigilant for severe icing conditions.
(3) If landing with an accumulation of ice, use a higher approach speed. Use a longer runway if available.
(4) Carry some power on flare and flare slightly faster than normal if carrying ice.
Use a longer runway if available.
(5) Cycle boots just before final approach.
(6) After touchdown, use brakes sparingly to prevent skidding.
4. Turbojet Aircraft.
a. Preflight.
Appendix 3 NOTE: Professional flightcrews flying complex, high performance aircraft should always refer to the AFM or POH and company guidance materials as the authority for procedures for flight into icing conditions.
(1) Because turbojet airplanes have the performance capabilities to fly around or quickly pass through areas where icing conditions are encountered in-flight, icing will pose more of a hazard during the takeoff phase. Therefore, particular attention should be paid to ground deicing.
(2) For ground deicing operations, refer to company procedures, AC 120-58, and AC 135-17 for guidance.
(3) Ensure that deicing fluids are not sprayed into engines, auxiliary power units, pitot inlets, probe openings, or static ports.
(4) Do not spray heated fluids onto cold windows.
(5) Deicing fluid fumes are toxic. If the aircraft is being sprayed with passengers on board, close all outside vents.
(6) Always obtain a thorough preflight weather briefing. Look for cloud types, bases, and tops; types of precipitation; freezing levels; and pilot reports.
(7) Preflight icing inspections of the aircraft in ground icing conditions are essential.
Tactile inspections are mandatory for some aircraft and are very valuable for detecting clear ice.
By physically touching the surface, any fine contaminants not easily visible can be detected.
Refer to AFM or POH to determine if a tactile inspection is mandatory for your aircraft.
(8) Ensure that all ice, frost, and snow is removed from the aircraft
(9) Ensure that heated flight information warning sensors, AOA, pitot/static, etc., are operating properly.
(10) Check pitot/static openings, fuel drains, and stall warning sensors to ensure they are not clogged with ice.
(11) Cycle anti-icing and deicing systems to check for proper operation.
(12) Clear any accumulated ice or snow from brakes and wheel fairings.
(13) Inspect the engine inlets of turbine engines and remove any accumulated ice from the nacelle inlet as well as around the nacelle drain hole and around the fan blades.
b. Taxi/Takeoff/In-Flight.
(1) Ensure that controls have full range of motion.
(2) Refer to the AFM or POH for proper operation of anti-icing and deicing systems.
A rule of thumb is that anti-ice systems should be activated at the first sign of visible moisture Page 6
Appendix 3 with air temperatures some margin above freezing. Deicing systems should be activated at the first sign of ice accretion.
(3) Power settings with bleed air on should be set according to the POH or AFM reference section.
(4) For turbine engines, perform regular engine power run-ups to shed accumulated ice while taxiing, per the AFM.
(5) Use visual cues to identify ice formation and regularly check for ice accumulation behind protected areas on the aircraft.
(6) Stay alert for ice formations in front of control surfaces that may cause control problems.
(7) If there is a need to use wing-deicing systems, there is a possibility that the empennage may be accumulating ice as well.
(8) Remember that recovery procedures from an ice-induced tailplane stall are opposite from those for an ice-induced wing stall.
(9) If using an autopilot, if workload permits, periodically disengage and manually fly the aircraft to identify handling changes caused by ice. This is especially important if operated in slow flight or in a holding pattern.
c. Approach and Landing.
(1) Be prepared for unexpected attitude changes when changing the airplane’s configuration. If the aircraft’s performance characteristics change suddenly, return to the previous configuration.
(2) Determine if freezing drizzle or freezing rain are being reported and avoid flying into these areas. A ground observation of ice pellets indicates possibly freezing drizzle or rain aloft. A ground observation of any type of precipitation when temperatures are near freezing may indicate freezing precipitation aloft, so be vigilant for severe icing conditions.
(3) Cycle boots before final approach, if equipped.
(4) In accordance with the POH or AFM, use a higher approach speed into the landing when carrying an accumulation of ice. Use a longer runway if available.
(5) Carry some power on flare and flare slightly faster than normal if carrying ice.
Use a longer runway if available.
(6) After touchdown, use brakes sparingly in case of ice buildup in brakes.
Appendix 4 APPENDIX 4. RECOMMENDED READING
1. This AC was developed as an easy-to-read resource on flight in icing conditions. As of the date of publication, this AC contains the most current information available. The suggested reading list that follows may not have been updated recently but may contain other useful and valid information. For more detailed information, pilots are referred to the following U.S.
Government publications:
a. Aeronautical Information Manual.
b. AC 00-6A, Aviation Weather for Pilots and Flight Operations Personnel.
c. AC 00-45F, Aviation Weather Services.
d. AC 20-29B, Use of Aircraft Fuel Anti-icing Additives.
e. AC 20-73A, Aircraft Ice Protection.
f. AC 20-113, Pilot Precautions and Procedures to be Taken in Preventing Aircraft Reciprocating Engine Induction System and Fuel System Icing Problems.
g. AC 20-117, Hazards Following Ground Deicing and Ground Operations in Conditions Conducive to Aircraft Icing.
h. AC 23.1419-2D, Certification of Part 23 Airplanes for Flight in Icing Conditions.
i. AC 91-51A, Effect of Icing on Aircraft Control and Airplane Deice and Anti-Ice Systems.
j. AC 150/5220-16C, Automated Weather Observing Systems for Non-Federal Applications.
k. NTSB Aircraft Accident Report AAR-96-01, In-flight Icing Encounter and Loss of Control Simmons Airlines, d.b.a. American Eagle Flight 4184 Avions de Transport Regional (ATR) Model 72–212, N401AM Roselawn, Indiana; October 31, 1994.
l. P-8740-24, Tips on Winter Flying — FAA Accident Prevention Program Publication.
2. For related reading materials, refer pilots to the following publications.
a. Buck, Robert N., Weather Flying, McGraw-Hill, Fourth Edition; 1998.
b. De Remer, Dale, Aircraft Systems for Pilots, Jeppesen Sanderson, Inc., 1996.
c. Flight Safety Digest, Protection Against Icing: A Comprehensive Overview, June-Sept. 1997, Flight Safety Foundation, 1997.
d. Hurt Jr., H. H., Aerodynamics for Naval Aviators, U.S. Navy, 1991.
e. Job, Macarthur, Air Disaster (Volume I), Aerospace Publications Pty Ltd., 1994.
f. Job, Macarthur, Air Disaster (Volume II), Aerospace Publications Pty Ltd., 1996.
g. MaChado, Rod, Instrument Pilot’s Survival Manual, The Aviation Speakers Bureau, 1997.
h. Newton, Dennis, Severe Weather Flying, McGraw-Hill, 1983.
i. Wild, Thomas W. Transport Category Aircraft Systems, Jeppesen Sanderson, Inc., 1990.
j. Mason, et al, The Ice Particle Threat to Engines in Flight. AIAA 2006, 44th AIAA Aerospace Sciences meeting and Exhibit, 9-12 January 2006, Reno, Nevada.