Fuel Emergencies: Guidance for Controllers

Fuel Emergencies: Guidance for Controllers


The term MINIMUM FUEL has, in the past, held different meanings for different aircraft operators and in different parts of the world. Until 2012, there was no dedicated phraseology to be used when it has been determined that an aircraft will land with less than final reserve fuel except the declaration of a MAYDAY nor has there been any dedicated phraseology to be used when it has been determined that an aircraft may land with less than final reserve if any delay not already notified were to occur.

Since 15 November 2012, amendments to both ICAO Annex 6 Part I and the Procedures for Air Navigation Services – Air Traffic Management (PANS-ATM) Doc 4444 have been in effect. They state:

Minimum fuel - The term used to describe a situation in which an aircraft’s fuel supply has reached a state where the flight is committed to land at a specific aerodrome and no additional delay can be accepted. (PANS-ATM, Doc 4444)

In circumstances where an aircraft has declared minimum fuel or is experiencing an emergency, or in any other situation wherein the safety of the aircraft is not assured, the type of emergency and/or the circumstances experienced by the aircraft shall be reported by the transferring unit to the accepting unit and any other ATS unit that may be concerned with the flight and to the associated rescue coordination centres, if necessary. (PANS-ATM, Doc 4444)

Minimum Fuel/Fuel Emergency Declaration

The declaration of "MINIMUM FUEL" informs ATC that, for a specific aerodrome of intended landing, the aircraft has sufficient fuel remaining to follow the cleared routing, execute an arrival and approach procedure and land with the required fuel reserves. However, there is little or no extra fuel on board and any change to the existing clearance could result in landing with less than planned final reserve fuel. (Diversion to alternate aerodrome is usually not an option except for cases where arrival and landing at the planned aerodrome includes considerable airborne holding.) MINIMUM FUEL is not a declaration which confers any special treatment by ATC, i.e. it is not an emergency situation, but merely an information message which, before this guidance was promulgated, would have led some operators to require that their pilots to declare a PAN. However, controllers should bear in mind that an fuel emergency may arise should any additional delay occur.

Controllers are not required to provide priority to pilots of aircraft that have indicated or suggested that they are becoming short of fuel or have used the RTF phraseology “MINIMUM FUEL”. The term MINIMUM FUEL indicates that the pilot, intending to land at a specific aerodrome, calculates that any change to the existing clearance to that aerodrome might result in landing with less than the planned final reserve fuel.

Controllers should also take into account that a particular State and/or aircraft operator's procedures may or may not require the use of MINIMUM FUEL and that PAN remains a universally prescribed means of declaring any urgency situation which requires assistance, and which in the case of such a declaration due to low fuel would require priority to be given. Controllers should also recognise that a PAN or a MAYDAY declaration arising because of low fuel may not necessarily use the fuel-specific phraseology suggested in PANS-ATM - the pilot may make a standard urgency or emergency declaration first and only once it has been acknowledged, explain that the problem is low fuel and priority corresponding to the declaration made is required.

Controllers shall respond to pilots, who indicate or suggest that they are becoming short of fuel or who have declared “MINIMUM FUEL”, by asking the pilot to confirm whether or not he wishes to declare an emergency after confirming to the pilot, the estimated delay (expressed in minutes) he/she can expect, if the pilot is en-route to, is joining, or is established in an airborne hold, or by expressing the remaining track mileage from touchdown, if the aircraft is being vectored to an approach.

Controllers should take into account that:

  • Low fuel quantity will limit the range and endurance of the aircraft.
  • A fuel leak will result in a continually worsening situation.
  • Expected route or arrival delays (e.g. due to weather) may result in a diversion decision (rarely an option) from the pilot before critical fuel levels are reached.
  • Fuel problems, such as a leak, fuel contamination or fuel depletion, could result in engine failure or forced landing

Common sense and good judgment will determine the extent of assistance to be given in minimum fuel situations. If, at any time, the remaining usable fuel supply suggests the need for traffic priority in order to ensure a safe landing, the pilot should declare an emergency ("MAYDAY FUEL") and report the estimated fuel endurance in minutes.

The pilot-in-command shall declare a situation of fuel emergency ”MAYDAY FUEL”, when the calculated usable fuel predicted to be available upon landing at the nearest aerodrome where a safe landing can be made is less than the planned final reserve fuel. Declaration of a fuel emergency is an explicit statement that priority handling by ATC is both required and expected.

Suggested Controller's Actions

Best practice, as embedded in the ASSIST principle, could be followed: (A - AcknowledgeS - SeparateS - SilenceI - InformS - SupportT - Time)

  • Clarify with the flight crew the actual fuel status, especially when there is a doubtful, vague or non-standard RTF used to inform about low fuel
  • If possible keep the aircraft at high altitudes to save fuel
  • Inform the crew, as necessary, about the distance to the nearest suitable aerodrome(s) and landing conditions
  • Avoid ATC-caused delays
  • Avoid missed approach due to ATC reasons
  • Inform the airport emergency services and all concerned parties according to local procedures;
  • Ask if dangerous goods on board
  • Ask for number of Persons On Board (POB)
  • Clear RWY according to local instructions
  • Keep safety strip clear
  • Have towing equipment on standby as appropriate

Note that the actions above are suitable for the MAYDAY FUEL scenario. In case of MINIMUM FUEL, the following steps are normally omitted, as they are only related to emergency situations:

  • Ask if dangerous goods on board
  • Ask for number of Persons On Board (POB)
  • Inform airport emergency services
  • Have towing equipment on standby


Circumstances Pilot Controller
Minimum fuel MINIMUM FUEL ROGER [NO DELAY EXPECTED or EXPECT (delay information)]
Fuel emergency MAYDAY, MAYDAY, MAYDAY, FUEL ROGER MAYDAY (any appropriate information)

The controllers should be aware that the flight crew can often be reluctant to declare a fuel emergency. ‘Fuel Emergency’ is not a term that is recognised in some States as a category of emergency - the pilot should be asked if he/she wishes to declare an emergency.

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