Flying Into Known Icing – Is It Legal?

Winter weather forecasts often include the threat of icing. But your Bugsmasher II lacks the equipment required for flight in


You are an experienced pilot and you are about to tackle a tough winter flight in your Bugsmasher II which (except for pitot heat, carburetor heat, and a 5-inch by 7-inch “storm window”) has no icing protection. Being inexact as usual, the area forecast calls for occasional light to moderate rime and mixed icing in clouds and precipitation along your flight path, throughout the duration of your intended flight.

Understanding that you need to look beyond the literal language of a forecast to determine what is really going on, you have learned that the reason for the icing forecast is that a cold front is approaching from the direction of your destination. You also have ascertained that the cold front is moving more slowly than expected and that you can probably beat the front. You will be flying toward deteriorating weather which will allow you at any time to reverse your course and land in more favorable conditions behind you. You decide that the forecast icing is a manageable risk and that you can take “adequate precautions” [See Scott’s earlier article, “Icing-Taking Adequate Precautions” – Ed.] against that risk. You conclude that it is safe to take off – but is it legal?

There are several reported cases that suggest that the answer is “No, flight in forecast icing is not legal.” That, however, is a narrow reading of the decisions. The more accurate response would be, “It depends.” Moreover, the question “Is it legal?” is not the appropriate inquiry. Rather, the questions you should be asking yourself are:

  1. Do you have the knowledge and experience to determine through the exercise of your good judgment that the flight is safe under the circumstances?
  2. Have you exercised your good judgment?
  3. Who are you placing at risk if your judgment is faulty?
  4. Under what rules are you conducting your flight?

When others are entrusting you with their lives, their safety should be your primary concern. As discussed below, if you address that issue appropriately, the regulatory issues will usually take care of themselves.

Is Flight in “Known Icing” Prohibited?

The harsh reality is that several National Transportation Safety Board decisions appear to construe Part 91 of the Federal Aviation Regulations as prohibiting your flying Bugsmasher II into any area where icing is forecast. That prohibition would survive whether the forecast is for icing that is “light,” “moderate,” or “severe,” and “intermittent,” “occasional,” “continuous” or “widespread.” Violations arising from flights in areas of forecast icing have been upheld even in the face of PIREPS of “negative icing.”

If you were flying a Part 135 mission (see Section 135.227) or piloting a “large” or turbine-powered aircraft (see Section 91.527) the regulations would provide you with detailed guidance concerning the types of icing and the types of forecasts that would preclude your departure. For you and Bugsmasher II, the guidance you receive is contained in Section 2 (“Limitations”) of your lowly Pilot’s Operating Handbook which somewhere says: “Flight into known icing conditions is prohibited.”

The decisions under Part 91 relating to icing say that it is a violation of the regulations to fly where icing is forecast if the POH contravenes flight into “known icing conditions.” More specifically, violations have been found under Section 91.9(a), which prohibits operations inconsistent with the limitations set forth in the POH. Violations have also been found under Section 91.13 which proscribes operations carried out in a “careless or reckless manner so as to endanger the life or property of another.”

Is Forecast Icing Equivalent to “Known Icing”?

The leading case, Administrator v. Bowen, arose from a December 1972 solo flight in a Bellanca 17-30A from Mineral Wells, Texas, to Marion, Ind. At the time of the flight, the Area Forecast, Airmet 1 and Sigmet Charlie 1 called for isolated or occasional moderate or severe icing in clouds or precipitation. The destination airport was IFR under a low overcast upon the pilot’s arrival. He was required to miss the initial approach and crashed due to an excessive accumulation of rime ice while attempting a second approach.

The commercial pilot was injured but survived. The Administrator initiated proceedings against him, alleging that he had operated the aircraft in noncompliance with its established operating limitations and, in so doing, had also operated in a careless or reckless manner. On appeal, the Board expressly rejected the pilot’s argument that mere forecasts of icing, in the form of the Area Forecast, Airmet and Sigmet, could not constitute “known icing” within the meaning of the POH. At the same time, the Board suggested that a pilot report of icing (or no-icing) might constitute more accurate information about actual conditions and hence that it might be “legal” to fly in areas where icing was forecast if someone had previously deigned to enter that area and also to transmit a no-icing PIREP.

The Board upheld a 15-day suspension of the pilot’s airman’s certificate, ruling:

[A] prefatory remark is in order concerning the phrase “known icing conditions,” in which respondent was alleged to have flown. We do not construe the adjective “known” to mean that there must be a near-certainty that icing will occur, such as might be established by pilot reports. Rather, we take the entire phrase to mean that icing conditions are being reported or forecast in reports which are known to a pilot or of which he should reasonably be aware.

Is It “Known Icing” Even If PIREPs Reflect That Icing Was Not Encountered?

For years following the Bowen decision, Part 91 pilots belabored under the misapprehension that it was “legal” to fly in areas where icing was merely a forecast event if they had received actual pilot reports reflecting the absence of ice. That misconception was shattered in 1993 when the Board issued its decision in the Groszer case.

In Groszer, a private pilot carrying one passenger crash-landed a Beechcraft Debonair short of the runway at Timmerman Field in Milwaukee, Wis. He had encountered icing in an area covered by a SIGMET for occasional, moderate to severe icing. In denying the pilot’s appeal, the Board rejected his argument that PIREPs of no-icing superseded the icing forecasts. The Board stated:

Respondent argues that he did not take off in known icing conditions. He believes that, despite the SIGMET, he was entitled to rely on those 3 of 4 PIREPs that indicated no icing at the altitude and along the route he planned. We cannot agree. It is not within [a pilot’s] discretion to pick and choose between the SIGMET and anecdotal PIREPs. … While PIREPs are valuable in planning (and are used in developing the SIGMETs), they are only one factor to consider. We, thus, do not agree with respondent’s claim that a pilot report will establish the absence of icing with “near certainty.”

The pilot was found to have operated his aircraft in contravention of its operating limitations and in a careless or reckless manner and, based on those findings, his private pilot certificate was suspended for 180 days.

How About Some Clear Direction Here?


If you’re going to suspend my certificate for flying in “Known Icing,” why don’t you just tell me not to do that?

Why are you sneaking up behind me and filing accusations quoting language from my Pilot’s Operating Handbook and interpreting vague terms like “careless” and “reckless”?

Why don’t you just promulgate a regulation stating that: “The operation under this Part of any aircraft not certified for flight in known icing conditions is prohibited anywhere that icing is forecast to be light, moderate, or severe, and intermittent, occasional, continuous or widespread?”

How about some clear direction here????


G.A. Pilot

The Regulatory Environment

G.A. Pilot lacks a good understanding of the regulatory environment. Regulations serve several purposes, among which are to control conduct and to erect and enforce barriers to entry. The regulations that are intended to control conduct are usually quite specific, such as the language of section 91.211 which mandates that the required minimum flight crew be provided with and use supplemental oxygen for the portion of any flight beyond 30 minutes at cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL). Such regulations tell you exactly what you are expected to do, and you are expected to act accordingly.

The regulations that are intended to be enforcement tools are usually written in broad, general language to give the regulator maximum leeway in exercising the prerogative to initiate enforcement proceedings. The language of section 91.13 prohibiting operations that are “careless or reckless … so as to endanger the life or property of another” is a classic example of a regulatory enforcement tool. The section gives virtually no guidance to the party being regulated and the maximum possible flexibility to the Administrator.

In areas where there is a perceived need for closer regulation to protect the general public, you will find more “control-type” regulations that substitute regulatory mandate for pilot judgment. The differences are readily apparent when you compare the regulations applicable to general aviation operations under Part 91 with the regulations applicable to charter operations (which pose a greater risk to the general public) under Part 135.

  • Gee, I’m kinda tired. Can I make this flight?
    Part 91: It’s up to your good judgment.
    Part 135: See Section 135.265.

  • Gee, the weather is good enough to depart IFR but I wouldn’t be able to make it back in on the approach. Should I depart?
    Part 91: It’s up to your good judgment.
    Part 135: See Section 135.217.

  • Gee, the weather is reported as being below minimums for the approach. Should I give it a try anyway?
    Part 91: It’s up to your good judgment.
    Part 135: See Section 135.225(a)(2),(b).

In the case of operations under Part 135 in any of the above cases, you could be cited unless you do exactly what the regulations tell you to do. In the case of operations under Part 91, you are allowed to use your good judgment. However, in the event you exercise poor judgment (or no judgment), you could be cited for being “careless” or “reckless.” Your having demonstrated your inability to exercise the good judgment required of a pilot in command under the Part 91 regulatory scheme, the Administrator may elect to invoke his barriers to entry to exclude you from further such participation.

Part 135 Restrictions on Flight in Icing Conditions

The prohibitions against flight in “known icing” conditions under Part 91 (in the absence of any regulation directly on point) can be better understood by reviewing the restrictions applicable under Part 135 in the context of a general understanding of the correlation between the two regulatory schemes. Under Part 135:

  • Section 135.227(c)(1) precludes flying an unprotected airplane into “known or forecast” light or moderate icing conditions in IFR conditions.

  • Section 135.227(c)(2) precludes flying an unprotected airplane into “known” light or moderate icing conditions in VFR conditions.

  • Section 135.227(e) precludes flying an unprotected airplane (whether under VFR or IFR) into “known or forecast” severe icing conditions.

  • Section 135.227(f) allows the pilot to ignore the prohibitions that would arise because of an icing “forecast” “if current weather reports and briefing information relied upon by the pilot in command indicate that the forecast icing conditions…will not be encountered during the flight because of changed weather conditions since the forecast.”

To translate:

So long as you can maintain VFR (clear of clouds) and so long as any applicable forecast is for moderate icing at the worst, you can fly under Part 135 in an area where icing has been forecast if, in light of all the information available to you, you have determined that you will not fly into conditions conducive to icing.

If you cannot maintain VFR, or if the forecast contemplates the possibility of severe icing, the Part 135 flight would be prohibited unless you can determine on the basis of weather conditions that have changed after issuance of the forecast that icing conditions will not be encountered.

Part 91 Restrictions on Flight in “Known Icing”

As you see, there are potential loopholes in the “known icing” prohibition even under Part 135 charter operations. The rules do not allow you to fly willy-nilly into areas where you know you will encounter icing. However, they do allow you to fly in areas where icing is forecast, so long as you have good reason to conclude that you will not be in icing conditions. As a general rule, your discretion to exercise your judgment is even greater under Part 91. You just cannot be “careless” or “reckless” in exercising it.

So What Do I Have to Do (Or Avoid Doing) to Keep My Certificate?

There are no simple answers here. The rule for GA pilots, to the extent that one exists, is that you are not allowed to fly an unprotected airplane into known icing conditions. An icing forecast constitutes “known” icing unless you have better and contradictory information available. However, the over-arching constraint is that GA pilots must exercise good judgment and avoid operations that are “careless” or “reckless.” Those general and somewhat competing principles are tempered by the following concepts and concerns:

There Is No Regulatory Safe Harbor to Exercise Rotten Judgment as PIC …

The GA pilot’s right to exercise judgment as pilot in command is both a privilege and a curse. It allows us to conduct operations under the rules applicable to general aviation that are forbidden under the rules applicable to charter and commercial transport operations. At the same time, since our rules lack explicit guidance, there often is no regulatory provision that you can point to as justification for your actions. You cannot rely blindly upon a pilot report of no icing and launch off into readily recognizable icing conditions. The rules allow and require you to exercise good judgment as pilot in command.

… There Are Different Rules for Different Flights …

This article is directed primarily to GA pilots who are both privileged and required to exercise their good judgment when confronting known or forecast icing conditions. It nevertheless bears mention that pilots in charter operations have a different set of rules. If you are flying for compensation or hire you have to comply with the rules that control your flight, even if your good judgment is that you could complete the flight safely.

… Your Level of Knowledge Is a Double-Edged Sword …

The folks who generate aviation weather forecasts may be based thousands of miles away from the areas covered by the forecasts and may be unfamiliar with local conditions and weather patterns. An experienced local pilot may have additional knowledge, insights and expertise that would support conclusions that differ from the forecast. If you are that pilot, you may choose to exercise your good judgment based upon that superior knowledge. If you are not that pilot, you are stuck with the forecast. That is the best information available to you.

The flip side of the “level of knowledge” equation is that the regulators raise the bar as you acquire additional certificates. The level of judgment expected of a commercial pilot is greater than that required of a private pilot. The level of judgment expected of an ATP is greater than that required of a commercial pilot. Together with the more expansive privileges come more extensive responsibilities.

… Mortality Is the Ultimate Safeguard Against Regulatory Action …

The common denominator between the decisions in this area is that the pilots survived the incident. In doing so, many of them conquered substantial odds. The ultimate sanction against foolhardy conduct as pilot in command is that you will perish, along with your passengers who relied upon you to exercise your good judgment when you elected to initiate the flight. If you devote the appropriate attention to safeguarding your safety and the safety of your passengers, the risk of regulatory sanctions can appropriately be given secondary consideration.

… Regulatory Exposure Increases with the Consequences …

In one decision in particular, both sides and the administrative law judge himself acknowledged that, but for the crash, the Administrator probably would never have commenced an enforcement action. If you crash – particularly if you cause injury to others – the chances are that there will be an enforcement proceeding. Your judgment will be assessed from a “hindsight is 20/20” perspective and you will have an uphill battle to justify your actions. However, if you have actually exercised good judgment you should be in position to explain how you determined that the flight did not impose undue risk to any of the persons involved. Moreover, if you exercise good judgment, you should not end up face down in a pool of ice in the first place. Remember, surviving nine out of ten flights just doesn’t cut it.

… Regulatory Scrutiny Increases According to the Exposure to Third Parties …

The wording of the “careless or reckless” provision warrants a close look. The operations that are proscribed are those carried out in a “careless or reckless manner so as to endanger the life or property of another.” Suicide prevention is not a principal focus of the FARs. They are intended to protect the innocent public from injury arising from pilots’ misconduct. Flying solo, your transgressions may be noticed. Flying with a planeload of neighborhood Camp Fire Girls, your actions will be scrutinized. Flying with a paying customer, your conduct will be subject to strict scrutiny. You should adjust your approach to forecast icing accordingly, because your friends and revenue passengers may not share your modest level of risk aversion.

… Enforcement Actions Tend to Arise from Multiple Violations

Students learn that they are likely to survive a mistake of judgment. They are less likely to survive two mistakes of judgment. They are likely to perish if they succeed in combining three or more mistakes in judgment.

The likelihood of suffering an enforcement proceeding frequently is also a function of a combination of miscues. The cases discussing errors of judgment in dealing with forecast icing usually also address several other judgmental lapses. Given the number of reported decisions and space limitations, I have not summarized all of them, but … consider these:

  • In 1992, a local businesswoman contacted a charter/FBO listed in the yellow pages to arrange a flight to a business meeting. The charter airplanes were all twins and the cost was more than she could (or would) pay, so the charter/FBO “rented” her a Piper Arrow (no de-ice here) and threw in a 1,000 hour commercial (non-Part 135) pilot for “no charge.” The forecast was for IFR (which would require a co-pilot under charter rules) and icing. Upon arriving at his destination in IFR/icing conditions, the pilot was unable to capture the localizer because the plane’s antiquated radios were incapable of receiving the localizer frequency. After twice being redirected to the localizer, the pilot reversed course and entered into a spiral descent to 500 feet AGL. Having lost communications with the Arrow, the controllers redirected an inbound Boeing 727 to avoid a collision. The pilot ultimately landed the Arrow successfully following a surveillance approach. The passenger reported that she had been frightened by the rapid descent and large chucks of ice coming off the wings during the descent. An enforcement action ensued.

  • Several years earlier, a commercial pilot departed VFR in a Cessna 150 for a 4.5-hour flight that ultimately terminated in Muncie, Ind. The pilot failed to investigate weather conditions prior to commencing the flight or en route. The pilot encountered forecast IFR weather and continued the flight VFR. The pilot encountered forecast icing and continued VFR. With less than minimum fuel, the pilot successfully landed his “thoroughly-iced” airplane at Delaware County Airport in Muncie, Ind., without communicating with the operating control tower and notwithstanding a 600-foot ceiling. Summoned to the tower to explain his unannounced arrival, the pilot was belligerent, barely capable of speech, unsteady on his feet and otherwise plainly intoxicated. The two deputy sheriffs who were summoned to the tower to address the situation subsequently testified that the pilot exhibited all the symptoms of a person completely under the influence of intoxicating liquor and opined that they would have arrested him for DUI had he been operating a motor vehicle. An enforcement action ensued.

In Summary

The decisions discussed at the outset of this article should not be read to stand for the proposition that flight under Part 91 is always improper in areas where icing is forecast. The cases hold that, under the circumstances of those specific cases and based at least in part upon the forecasts, the accused pilots knew or should have known they were flying into icing conditions and exercised poor judgment in doing so. The rule, then, is that you may be sanctioned if you exercise poor judgment in flying into icing conditions that you should have anticipated based on ALL the information that you know or should know.

If you do not want to be held accountable for exercising poor judgment as pilot in command, surrender your certificate. That, in large part, is how Part 91 operates. You may not be a certified A&E mechanic, but Section 91.7(b) holds you ultimately responsible for determining that the airplane is in an airworthy condition. You may not be a meteorologist, but Sections 91.9(a) and 91.13 impose upon you the obligation of exercising good judgment as pilot in command to assure that forecast and known icing conditions will not endanger the life or property of another.

When confronted with an icing situation, if you ask yourself the questions posed at the outset of this article and respond appropriately, you will probably be okay. You will be exercising good judgment. You will not be exposing others to inordinate risks. You will probably not crash. The only thing working against you, from a regulatory enforcement standpoint, is that you also will probably survive all the potential conditions that you have accounted for. But that’s not altogether a bad thing.

For a thorough discussion of what airframe icing is, how it forms, where it comes from and what you can do to get out of it, be sure to check R. Scott Puddy’s initial article, “Icing – Taking Adequate Precautions.”