Pilot Counsel

The law on 'known icing'

August 1, 2005

AOPA's legal counsel, attorney John S. Yodice, flies a Cessna 310.

Pilots understand that the federal aviation regulations prohibit flight into "known icing conditions" unless the aircraft is specifically certificated by the FAA for such flight and has the required anti-ice/deice equipment (very few light general aviation aircraft have that kind of certification).

Rather, what has been a much-debated quandary for pilots is the interpretation of the phrase "known icing conditions." The regulations don't define the phrase, and the FAA offers very little guidance to pilots operating "non-commercially" under FAR Part 91 (the commercial rules are more explicit) except in individual enforcement cases that it litigates before the National Transportation Safety Board. Then it is the NTSB, in its enforcement decisions, that creates the precedent interpreting "known icing conditions." This context is troublesome because, in the effort to secure a "conviction" in an individual case, the established precedents, if literally applied, could have the unintended effect of unnecessarily grounding many safe light GA flights.

Pilot reports of icing

The law on "known icing" is mostly old and not well known. Here is the most recent NTSB interpretation as it relates to pilot reports (pireps) of icing. It comes in a case involving a flight instructor who was giving instrument instruction to the owner of a Cessna 172, a private pilot who was working toward an instrument rating. The flight was on an IFR flight plan to Paine Field, Everett, Washington. The flight plan indicated that multiple training approaches would be made. The owner/trainee was piloting the aircraft, executing the first of a number of planned missed approaches, when the flight instructor noticed ice on the wings. The flight immediately returned for a landing. The field was IFR. On the approach to landing, the pilot reported having difficulty maintaining altitude. On short final, about 10 to 15 feet above the ground, the aircraft's left wing dropped. The aircraft landed hard on the left main gear and bounced. The pilot added power in an attempt to stabilize the aircraft. The flight instructor then took control of the aircraft but was unable to regain directional control. The aircraft ran off the runway and was substantially damaged. The pilots were not injured.

Of course, icing was the focus of the FAA investigation. It was determined that prior to the flight, the owner/trainee obtained a computerized weather report that showed overcast skies and a temperature of 2 degrees Celsius at Paine Field. There was no specific forecast of icing. Later, immediately before the flight, the owner/trainee was advised that the cloud tops at Paine Field were 2,100 feet.

The FAA charged the flight instructor with regulatory violations that essentially come down to a charge of operating an aircraft into known icing conditions. Surprisingly, there is no such specific FAR for Part 91 operations. The actual charges were two. The first is a violation of FAR 91.9(a) that prohibits operating an aircraft without complying with the operating limitations specified in the approved flight manual, markings, and placards. As is typical for many light GA aircraft, the manual for the 172 prohibits operations into known icing conditions, and the aircraft was placarded against such operations. The second charge was a violation of FAR 91.13(a) that very generally (not specific to icing) prohibits careless or reckless operations so as to endanger the life or property of another. The FAA suspended the instructor's commercial and flight instructor certificates for a period of 90 days.

The flight instructor appealed the suspension to the NTSB. A hearing was held before an NTSB law judge, and the FAA introduced three critical pieces of evidence. First, the FAA introduced evidence intended to show that the flight instructor ignored two pireps of rime icing to the sector controller — reports that should have been overheard by the flight instructor. Second, the FAA introduced expert testimony that the flight instructor should never have undertaken the flight because he should have known from the weather report and briefing that the flight would have to descend and ascend into clouds and icing conditions at Paine Field to perform the training missed approaches. Third, the FAA introduced the testimony of the owner/trainee that the flight instructor actually pointed out ice on the wing and then performed the missed approach, instead of landing or climbing above the clouds and proceeding to a VFR airport free of the danger of ice buildup. In other words, according to the owner/trainee, even though they saw ice on the wing, the flight instructor had him do the missed approach rather than land.

The flight instructor's testimony was different. He did not recall showing the owner/trainee ice on the wings before the missed approach. He did not recall hearing either of the two icing pireps. And, he said, he took action to land as soon as possible after he saw ice on the aircraft after the missed approach. The law judge did not credit the flight instructor's testimony. Rather, based on the FAA evidence, the law judge upheld the FAA charges and the 90-day suspension. The flight instructor then appealed the law judge's decision to the full board.

One of the important issues before the board was the meaning of "known icing conditions" as it relates to a pirep. We will discuss "forecasts" later. Is a pirep a report of known icing conditions? Under the circumstances of this case, the board answered, yes. The board rejected the flight instructor's claim that the pireps were not stated as within his flight path, and so he was not required to take them into account — even if he had heard them, which he claimed he had not. The law judge specifically found that the flight instructor should have discerned that at least one of the pirep aircraft was in the vicinity of Paine Field. That's because ATC advised the other aircraft on frequency that this aircraft could not be given a requested altitude of 4,000 feet because another aircraft was already there. The law judge concluded that the flight instructor's aircraft was the one at 4,000 feet, and the flight instructor should have known it. The board agreed and also concluded that the flight instructor should have heard the two pireps, and that: "It would have been prudent, at a minimum, to query ATC when a report of icing in his sector was broadcast so that he could assess the threat. He failed to do so. Absent clarification that the icing was not a threat to his aircraft, he risked flying into 'known icing conditions.'"

So, the NTSB is clearly saying that a pirep is a report of known icing conditions. The board seems to leave open the door to establish that the pirep was not relevant to the flight in question. However, it also seems to be saying that if an icing pirep is overheard on the ATC frequency being monitored (i.e., the same "sector"), a pilot must query the controller to assess whether the icing is a threat to the aircraft.

Forecast of icing

The other burning issue that is not addressed in this recent case is whether a forecast of icing is "known icing conditions." Many pilots argue that "known" means known, not forecast, and that a forecast is a prediction and not "known." They argue that the forecasts themselves further undercut "known" by using such terms as "chance of" or "possibility of." The board addressed this issue most recently more than a dozen years ago, and in 1974 and 1976 before that. All are old cases.

The dozen-year-old case involved a private pilot who crash-landed his aircraft just short of a runway. Ice was found on the aircraft's wings. The FAA suspended his certificate for 180 days because he took off in the face of a sigmet indicating the potential for occasional moderate to severe icing over a broad area that included his departure and destination airports, and the area in between, at altitudes between 3,000 to 11,000 feet (he planned to fly at 4,000 feet). Even the board conceded that there was no question that the pilot acted cautiously, returning to the flight service station at least three times to clarify matters and rejecting his first choice of destinations as too risky in light of the weather.

In the final analysis, though, the pilot relied on three pireps that indicated no icing at the altitude and along the route he planned to fly. He spoke to a pilot who had landed at the departure airport 45 minutes previously, from an altitude of 12,000 feet, and who had experienced no structural icing. According to the pilot, he reasonably concluded that there were no icing conditions that would affect his flight. For our purposes in this column, the significant issue in the case is the pilot's argument that he did not take off in known icing conditions. The board, squarely facing the issue, held that "known does not mean a near-certainty of icing conditions, only that icing conditions are being reported or forecast." A forecast of "the potential" for icing is "known icing conditions" to a pilot. The 1974 and 1976 cases hold the same way.

The NTSB precedents are clear. Relevant pireps and forecasts constitute "known icing conditions" into which a flight is prohibited unless the aircraft is specifically certificated by the FAA for flight into known icing conditions.