ASRS Directline

 Issue Number 3 : July 1992

Great Expectations: Minimum Fuel Situations

by Jeanne McElhatton

Few in-flight problems are guaranteed to raise the concern of pilots and controllers alike as much as the prospect of an aircraft running out of fuel. In the period following the Avianca accident in January of 1989 (where Avianca Flight 52 crashed short of its destination after running out of fuel), the ASRS has seen a rise in the number of reports that concern "low-fuel" conditions. Reports may detail the confusion and communications breakdown among flight crews and controllers about what is meant by a "minimum fuel" situation. In more than a few situations, conscientious and understandably vigilant controllers have elevated to emergency status what the flight crew intended only as an advisory.

Given ATC's reaction to what they may perceive as a critical fuel condition in this incident report, it's not surprising that pilots might hesitate to use the term "minimum fuel." Flight crews tend to feel that a controller response such as the one illustrated above will create mounds of paperwork, and they certainly wish to avoid that. This flight crew never even used the phrase "minimum fuel," but their flight was handled as an emergency because they had mentioned their limited fuel status.

Sometimes, however, the scene plays the other way and the message does not get through even though stated clearly. The flight crew must then declare minimum fuel and request priority.

This flight crew stated their developing fuel condition; however, this information may not have been relayed to the next controller. Both controllers and pilots have a mixed perception of, and perhaps response to, the term "minimum fuel."

Great Expectations -- the Pilot's Perspective

Pilot expectation of the use of the term "minimum fuel" is most often Air Traffic Control (ATC) assistance by way of direct routing, minimal or no holding, and no off-course vectors, but this expectation is not always operationally feasible. Minimum fuel does not mean priority handling to all pilots; it most certainly does not of itself indicate emergency.

Some pilots are very disturbed because they do not receive expected assistance when stating minimum fuel. Others are disturbed because a controller appears to unilaterally declare an emergency and give priority handling.

One pilot suggests that controllers do not really understand the term "minimum fuel." He might well have included pilots in that statement.

Interpretation and semantics appear to be a major part of the great expectations mix-up. Terminology played a roll for this flight crew:

Note the reporter's belated assessment of his choice of terminology. His final thoughts are correct; this would have been precisely the proper use of a minimum fuel declaration.

Controller Perceptions

What is the controller perception and/or expectation when "minimum fuel" is used? One Controller's response was "Minimum fuel doesn't mean a thing to me." Another, and opposite response, is "Understand you are declaring an emergency." Controllers are also prone to ask if assistance or emergency equipment is needed. They most often try to offer assistance, and may even declare an emergency -- much to the flight crew's dismay.


Controllers declare emergencies -- pilots resist the declaration, but expect priority handling. There is an obvious misconception in the use of the term "minimum fuel." The phrase does not require, order, or demand priority handling; however, many pilots have come to use the term as if that is what it does mean -- the "Great Expectation." A pilot writes:

Just as pilot and controller expectations may be quite varied, you can see their that responses are equally so. When information is passed from controller to controller, some information may get lost or misinterpreted. Each party, controller and pilot, has a specific job to accomplish. Those jobs can be accomplished with understanding, cooperation, and professionalism.

Take AIM

Let's review what the Airmen's Information Manual (AIM) states regarding minimum fuel.


a. Pilot --

  1. Advise ATC of your minimum fuel status when your fuel supply has reached a state where, upon reaching destination, you cannot accept any undue delay.

  2. Be aware this is not an emergency situation, but merely an advisory that indicates an emergency situation is possible should any undue delay occur.

  3. Be aware a minimum fuel advisory does not imply a need for traffic priority.

  4. If the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing you should declare an emergency account low fuel and report fuel remaining in minutes. (Reference -- Pilot/Controller Glossary, Fuel Remaining).

Note that this portion, referencing pilots specifically, states this advisory does not imply a need for traffic priority. What to do if the need for traffic priority develops? The message is clear -- declare an emergency.

Let's carry on with part (b) of the 5-85. Minimum Fuel Advisory, and see what is recommended for the controller.

b. Controller --

  1. When an aircraft declares a state of minimum fuel, relay this information to the facility to whom control jurisdiction is transferred.

  2. Be alert for any occurrence which might delay the aircraft.

Note that the minimum fuel declaration is an advisory only, it is not a specific request for priority handling. It should be considered a "yellow caution flag" indicating future problems may develop if undue delays occur.

Air Traffic Procedures Handbook

Air traffic controllers may not refer to the AIM on a regular basis, but ATP 7110.65 references minimum fuel:

MINIMUM FUEL -- Indicates that an aircraft's fuel supply has reached a state where, upon reaching the destination, it can accept little or no delay. This is not an emergency situation but merely indicates an emergency situation is possible should any undue delay occur.

Advice for Pilots

What can you do if minimum fuel gets you?

  1. Monitor fuel consumption and have an alternate plan if things don't look as if they will turn out as planned;

  2. If you decide that a minimum fuel situation exists, or is likely to exist at some point down the line, determine the point beyond which you will not continue in accordance with the original flight plan and what your alternate plan of action will be;

  3. Communicate! Tell ATC exactly what your situation is, and make sure they understand it. Inform the controller how long you can continue on their original clearance or route before a diversion becomes necessary, restate the situation to the new controller on a handoff, or otherwise clarify the situation if appropriate. Consider advising ATC on each successive frequency that a minimum fuel situation exists. Note the following communication that kept ATC aware of the minimum fuel situation;

  4. Plan ahead -- don't wait until fuel is critical and the situation really does become an emergency;

  5. Finally, remember the declaration of an emergency does not put you on trial. It may require a report to the company, or a "letter" to the FAA Administrator (only if requested), or it may not require a thing.

Advice for Controllers

What can you do to reduce both risk and frustration?

  1. Be aware of the nuances of a minimum fuel statement. What is the flight crew really saying? You may need to question the flight crew until the situation is mutually understood;

  2. Remember to relay to the next controller the "minimum fuel" status of any aircraft;

  3. Keep your expectations within the limitations of the advisory on minimum fuel.

So, take a fresh look at the term "minimum fuel." Do you and the AIM interpret it the same way?

Final Thoughts

One ASRS reporter presented an interesting suggestion that would keep everyone informed of an unusual or abnormal fuel state:

Excellent food for thought. This suggestion would keep communications to a minimum, would be passed along on the data block from sector to sector, or to another facility. The pilot could be asked to state specifics of the situation, which would hopefully clarify the situation for all parties. An interesting proposal to consider.

It has also been suggested that the FAA develop an ATC computer enhancement that keeps track of flying time remaining -- as stated by the pilot during minimum fuel situations. At an appropriate time before fuel exhaustion, the aircraft's computer data block would flash intermittently to remind the controller of the flight's fuel status before it reaches the critical stage.

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