8. When should a “minimum fuel” declaration be made? Minimum fuel should be declared anytime that an aircraft, if it were to be delayed, might end up in a low fuel emergency situation. Most air carriers have a specific value at which this should be declared.
9. When should a low fuel emergency be declared? A low fuel emergency should be declared anytime an aircraft falls below minimum fuel values and is in imminent danger of running out of fuel. Most air carriers have a specific value at which this should be declared.
Ison, David C.. Aircraft Dispatcher Oral Exam Guide (Kindle): Prepare for the FAA Oral and Practical Exam to Earn Your Aircraft Dispatcher Certificate (Oral Exam Guide Series) (Kindle Locations 6181-6187). Aviation Supplies and Academics, Inc.. Kindle Edition.
from the AIM
5-5-15. MINIMUM FUEL ADVISORY
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. On initial contact the term "minimum fuel" should be used after stating call sign.
EXAMPLE-
Salt Lake Approach, United 621, "minimum fuel."
4. Be aware a minimum fuel advisory does not imply a need for traffic priority.
5. If the remaining usable fuel supply suggests the need for traffic priority to ensure a safe landing, you should declare an emergency due to low fuel and report fuel remaining in minutes.
REFERENCE-
PILOT/CONTROLLER GLOSSARY ITEM- FUEL REMAINING.
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.
so then declare minimum fuel then and if ATC still doesn't understand declare an emergency?
Look at this American airlines flight and how assertiveness makes for a safe outcome.
On the contract look at this DFW American airlines flight where they were denied the runway they wanted even though they declared.
In that case using his emergency authority, that captain should have said to the controller to shove it and start clearing metal out of his way. Guaranteed a carpet dance must have occurred after the fight between AA and ATC. The flight landed safely but it would be interesting to see the feds reaction had the pilot said screw it to ATC and used 17 despite it being on the tapes atc denying him that runway. Feds most likely would have told him good on you for using your emergency authority and to ATC he had every right to disobey your orders. Denying an emergency flight their choice of runway..wow..just wow.