Fuel MAYDAY with Weather Below the Approach Minima
At 05:50 UTC, approach control at an aerodrome with runway 22 (3,000 m) is handling three arrivals in holding. Weather is fog: RVR 400 m, vertical visibility 100 ft. The ILS CAT I minima for runway 22 are 550 m RVR and 200 ft decision height. A Boeing 737-800, 35 NM south, transmits 'MAYDAY, MAYDAY, MAYDAY, fuel, 15 minutes remaining.' The aircraft is IFR and requests an immediate approach. Its nominated alternate is 90 NM away with marginal weather. Two other aircraft are holding at FL070 and FL090. Low visibility procedures have not yet been declared, and the tower is not aware of the emergency. The controller must prioritise the emergency, coordinate with the tower, and decide how to handle the weather below minima and the other traffic.
1. What should the controller do in the first minute after the MAYDAY?
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Acknowledge the distress call immediately and give the aircraft priority without a lengthy interview. NGA123, MAYDAY acknowledged, squawk 7700, cleared direct ILS runway 22, descend 3,000 ft, report fuel remaining and persons on board. If the transponder is already set, confirm it. Clear the aircraft direct to the final approach fix, stop other departures and arrivals, and coordinate with the tower to protect runway 22 and alert RFFS to full emergency status. Inform the approach supervisor and airport operations.
Ask only essential questions: fuel endurance, persons on board, and whether the pilot intends to attempt the approach. Do not delay the clearance to obtain administrative details. The priority is to get the aircraft on the ground or to a safe alternate before fuel is exhausted.
2. The RVR is 400 m, below the 550 m ILS CAT I minima. May the controller clear the aircraft for the approach, and who decides?
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The controller must pass the actual weather and RVR and ask for the pilot's intentions. ATC does not 'authorise' an approach below minima; the decision to commence or continue an approach below published minima rests with the pilot in command, and in a fuel emergency the pilot may elect to try. Phraseology: NGA123, latest RVR runway 22, 400 m, below CAT I minima, report intentions. If the pilot requests the approach, clear it and protect the airspace; do not refuse priority because the weather is below minima.
The controller should also advise the alternate weather and be ready for a diversion. If the pilot continues and goes around, the aircraft may have insufficient fuel for a second approach, so the tower must be ready to clear the runway and provide the shortest possible routing.
3. How should the two aircraft in holding be managed while the emergency is handled?
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Keep the holding aircraft clear of the emergency approach path and give them traffic information and expected delay. Ask for their fuel state early: ABC123, emergency traffic on approach, expect further delay, report fuel endurance. If either holding aircraft becomes fuel-critical, treat it as a separate emergency and coordinate diversion or priority sequencing.
Do not release the holding aircraft for the same runway until the 737 has landed and vacated, or until the 737 diverts. If the 737 lands and the runway is blocked, instruct the holding aircraft to continue holding or divert. Record the instructions, times, and fuel states. After the event, file an occurrence report covering the emergency priority, the below-minima approach, and the holding delays.