Holding at a Busy Gulf FIR with a Deteriorating Destination

Fuel plan from the present position.

• Fuel on board now: 6 800 kg
• Trip fuel to OOMS: 2 900 kg → fuel at OOMS ≈ 3 900 kg
• Contingency 5 % of 2 900 = 145 kg
• Final reserve 30 min at 1 100 kg/h = 550 kg
• Alternate fuel OOSA = 3 600 kg

Required at OOMS for a Salalah diversion = 3 600 + 550 + 145 = 4 295 kg.

Fuel at OOMS ≈ 3 900 kg < 4 295 kg → you cannot divert to Salalah after reaching Muscat with the planned reserves. The shortfall is about 395 kg.

Implication: the aircraft is committed to Muscat once it passes the point of no return for Salalah. The correct decision point is now, not at Muscat: either

1. Divert to Salalah before the equal-time point, or
2. Obtain a closer alternate (e.g. an airfield within ~150 nm) that reduces alternate fuel to below 3 350 kg, restoring the reserve, or
3. Hold only if the holding fuel is protected by a revised flight plan that does not eat into the final reserve.

Holding at Muscat with this fuel state is not acceptable: 3 900 kg gives about 3 h 30 min total endurance, but the legal reserve is what matters, and the Salalah option is already lost.

Minima logic.

• Reported visibility 2500 m, TEMPO 800 m in blowing dust. For a precision approach (ILS CAT I) the applicable RVR/visibility minimum is typically 550 m RVR for CAT I with the relevant lighting, but the visibility reported in dust is a meteorological visibility, and the operator's OM converts it to RVR. With 800 m in the TEMPO, a CAT I ILS is still theoretically usable if the RVR is ≥ 550 m - but the TEMPO is a forecast, not a report, and the commander must plan for the worst of the TEMPO during the approach.
• Blowing dust at 38 °C with a 12 °C dewpoint gives a large spread (no fog risk), but dust reduces slant visibility and can obscure the runway environment even when the horizontal visibility is 1500 m. The few cloud at 3000 ft is not a factor for a CAT I ILS.
• The runway has a displaced threshold: the landing distance available is reduced, and the touchdown zone is further from the threshold. At 38 °C the true landing distance increases by roughly 1 % per 1 °C above ISA (ISA at 15 m ≈ 15 °C, so ΔT ≈ +23 °C → about +23 % on the dry distance). With a displaced threshold the LDA must be checked against the factored landing distance for the actual landing mass.

Decision. The approach is legal but not comfortable: the TEMPO 800 m is above the CAT I RVR minimum, but the combination of dust, displaced threshold and high temperature means the go-around decision must be made early. Brief a CAT I ILS to runway 26L with a firm go-around at DA(H) if the runway environment is not clearly visible, and hold enough fuel for one approach and a diversion to the closer alternate. If the actual RVR at the outer marker falls below 550 m or the reported visibility drops to 800 m as a prevailing, not TEMPO, condition, divert.

Holding burn. 20 min at 1 800 kg/h = 600 kg.

Fuel at OOMS after holding ≈ 3 900 − 600 = 3 300 kg.

Reserve check. Final reserve 550 kg + contingency 145 kg = 695 kg protected minimum. Alternate fuel to OOSA 3 600 kg is now not available: 3 300 kg < 3 600 kg, so a Salalah diversion is impossible.

• Fuel above final reserve = 3 300 − 550 = 2 750 kg - about 1 h 30 min at 1 800 kg/h, but that is not a legal alternate reserve.
• The aircraft is now committed to Muscat with no legal alternate. The only acceptable continuation is a straight-in approach with a go-around protected by the final reserve, and a diversion to a closer airfield if one can be reached within the fuel above final reserve.

Action. Declare a fuel situation to ATC (minimum fuel / MAYDAY FUEL if the final reserve is likely to be breached), request priority, and plan a single approach. If the approach is not successful, the go-around must be to a closer airfield, not Salalah. The lesson: the decision to hold should have been made only after confirming a closer alternate was available; holding with a 450 nm alternate and no extra fuel is the error.