Regulation Text
(a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface; to a powerplant installation; or to an airspeed, altimeter, rate of climb, or flight attitude instrument system or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks if authorized by the FAA.
(b) No pilot may fly under IFR into known or forecast light or moderate icing conditions, or under VFR into known light or moderate icing conditions, unless—
(1) The aircraft has functioning deicing or anti-icing equipment protecting each rotor blade, propeller, windshield, wing, stabilizing or control surface, and each airspeed, altimeter, rate of climb, or flight attitude instrument system;
(2) The airplane has ice protection provisions that meet section 34 of Special Federal Aviation Regulation No. 23; or
(3) The airplane meets transport category airplane type certification provisions, including the requirements for certification for flight in icing conditions.
(c) Except for an airplane that has ice protection provisions that meet the requirements in section 34 of Special Federal Aviation Regulation No. 23, or those for transport category airplane type certification, no pilot may fly an airplane into known or forecast severe icing conditions.
(d) If current weather reports and briefing information relied upon by the pilot in command indicate that the forecast icing conditions that would otherwise prohibit the flight will not be encountered during the flight because of changed weather conditions since the forecast, the restrictions in paragraphs (b) and (c) of this section based on forecast conditions do not apply.
[Docket 18334, 54 FR 34314, Aug. 18, 1989, as amended by Amdt. 91-310, 74 FR 62696, Dec. 1, 2009]
Research Notes
Section 91.527 — Operating in icing conditions — restricts operations of large airplanes in icing conditions to those certified for flight in icing.
The icing rule: No PIC of a large airplane may operate in known icing conditions UNLESS the aircraft has functioning deicing or anti-icing equipment for the flight surfaces affected. The aircraft type design and AFM specify whether the aircraft is approved for flight in known icing.
'Known icing' interpretation: The FAA Chief Counsel has interpreted 'known icing conditions' broadly — including PIREPs of icing, AIRMETs forecasting icing, visible moisture below freezing, and surface observations of icing on aircraft. Pilots may not enter known icing without appropriate equipment certification.
FIKI (Flight Into Known Icing) certification: Aircraft equipped and certified for Flight Into Known Icing have boot or bleed-air deice systems, heated windshields, heated pitot/static, and other icing protection. Their AFMs specifically authorize known-icing operations.
Inadvertent encounters: If a pilot inadvertently enters icing in a non-FIKI aircraft, the obligation is to exit the icing condition as soon as practicable. The PIC may declare emergency under § 91.3(b) to deviate from clearance for safety.
Reference: AC 91-74B on known icing operations; AC 23-15 on icing certification for normal category airplanes.
Amendment History
Amendment History Coming Soon
Every time this regulation changes, we'll record it here — the date, what was amended, and a plain-English summary of what shifted.