Pilot Counsel

IFR fuel reserve

December 1, 2010

John Yodice Even with careful preflight planning and in-flight monitoring, you could find yourself unexpectedly short on fuel, adding to your calculations for a safe landing, and maybe a concern about eating into your IFR fuel reserve. A relatively recent FAA chief counsel interpretation answered whether a pilot may “legally” use some of the required 45-minute minimum IFR fuel reserve without declaring an emergency. This gives me an opportunity to clarify the difference between declaring a fuel “emergency” and giving ATC a “minimum fuel advisory.” It is also an opportunity to raise the issue of the pilot in command’s emergency authority.

As background, let’s review FAR 91.167, which specifies the fuel requirements for flight in IFR conditions. It says that, “No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to: Complete the flight to the first airport of intended landing; Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and Fly after that for 45 minutes at normal cruising speed [helicopters different].”

The paragraph (b) exception allows a pilot to eliminate from his or her computation the fuel necessary to fly from the first airport to the alternate if the first airport has a standard or special instrument approach, and it is expecting generally good weather (i.e., for at least one hour before and one hour after the estimated time of arrival, the relevant weather reports/forecasts indicate that the ceiling will be at least 2,000 feet above the airport elevation and visibility will be at least three statute miles—the familiar memory device of “1-2-3”). In that case the basic rule is simply that enough fuel must be carried to land at the destination airport plus a 45-minute reserve computed at normal cruising speed and altitude. In both cases a 45-minute fuel reserve is required.

What about landing without all of the required reserve in the tanks? I have stated that where the facts show proper preflight planning and en route monitoring, merely landing without the full 45-minute fuel reserve, by itself, does not constitute a violation of FAR 91.167.

The question the FAA chief counsel answered is slightly different. He answered yes to whether a pilot may “legally” use some of the 45-minute fuel reserve without declaring an emergency. He says: “The FAA has advised pilots to declare a fuel emergency [only] when, in the pilot’s judgment, it is necessary for him or her to proceed directly to the airport at which he or she or she intends to land.”

How is that different from a “minimum fuel advisory”? The two may sound alike, but an advisory is definitely not a declaration of an emergency. According to the Aeronautical Information Manual, a minimum fuel advisory to ATC is appropriate when your fuel supply has reached a state where, upon reaching the destination, you cannot accept any undue delay. There is no regulatory requirement that such an advisory be given to ATC. However, it does indicate to ATC that an emergency situation is possible should any undue delay occur. It does not imply a need for traffic priority, but declaring a fuel emergency does. According to the AIM, “If the remaining usable fuel supply suggests the need of traffic priority to ensure a safe landing, you should declare an emergency due to low fuel and report fuel remaining in minutes.”

So, whether to declare a fuel emergency or give a minimum fuel advisory is much within the judgment of the pilot. The controlling issue is whether the pilot believes he or she needs priority handling to effect a safe landing, i.e., an emergency; or whether ATC should merely be put on alert against any occurrence that might delay the aircraft, i.e., a minimum fuel advisory.

What the interpretation does not discuss is the possible relevance of FAR 91.3. Recall that this is the rule that gives the pilot in command the final authority as to the operation of the aircraft, and consistent with that authority, allows the pilot who is experiencing an in-flight emergency to deviate from any rule of Part 91 to the extent required to meet that emergency. This authority is well known to the pilot community. It is not usually second-guessed by the FAA except in one limited circumstance—where the emergency is of the pilot’s own making. In many instances, low on fuel is arguably of the pilot’s own making. While concern about FAA enforcement should never be a reason not to declare an emergency, it may well be in the back of the pilot’s mind, complicating an already very difficult decision. Whatever the decision, hopefully culminating in a safe landing, one of the first things the pilot should do on landing is to call the AOPA Legal Services Plan, and secondly, to file a NASA Aviation Safety Report. Safely on the ground, we can then wrestle with the possibility of an FAA violation.

John S. Yodice and Associates provides legal counseling to AOPA and its members.