Turkana charter: dispatch pressure, destination alternate and fuel
A single-pilot Cessna 208B Caravan is chartered from Nairobi Wilson (elevation 5,532 ft) to an unlit airstrip in Turkana (elevation 1,700 ft) with three passengers. ETD is 16:20 EAT; ETA is 18:40 and sunset at the destination is 18:47. The AIP lists the strip as daylight operations only. There is no TAF. The area forecast for the arrival period gives scattered cumulus, embedded CB and temporary visibility 5,000 m in thunderstorm rain. The only instrument approach is an NDB procedure with MDH 520 ft and visibility 4,800 m. The flight plan names Eldoret as destination alternate. Planned figures are: taxi 30 lb, trip 737 lb, contingency 5% (37 lb), alternate 227 lb, final reserve 170 lb. Fuel on board is 1,050 lb. The dispatcher argues that the forecast visibility of 5,000 m is above the 4,800 m minima, so no alternate is needed and 1,050 lb is plenty.
1. May the flight be planned to the Turkana strip on the strength of the area forecast? State whether a destination alternate is required and justify your answer.
Read the worked answer
No. The KCARS operating rules, which follow ICAO Annex 6, allow an IFR flight to be planned to a destination without a destination alternate only where the weather at the estimated time of arrival, and for a reasonable period either side, is at or above the approach and landing minima, or the aerodrome has suitable separate runways. Here there is no TAF at all, only an area forecast containing embedded CB and TEMPO 5,000 m in thunderstorm rain. The dispatcher is taking the best figure in the forecast and ignoring its variability: a temporary condition 200 m above the visibility minima, inCB, can easily go below minima at the ETA, and the 1,500 ft cloud associated with the CB would already prevent the visual manoeuvre. A destination alternate is therefore required.
A second, independent problem: arrival at 18:40 with sunset at 18:47 and a daylight-only, unlit strip leaves no margin. A ten-minute delay, a hold or one missed approach puts the aircraft at an unlit aerodrome after dark. The plan is not acceptable even before fuel is considered.
2. Check the fuel plan against the requirement and state the result in pounds and minutes.
Read the worked answer
Minimum required fuel (turbine aircraft, IFR):
| Component | Value |
|---|---|
| Taxi | 30 lb |
| Trip fuel | 737 lb |
| Contingency, 5% of trip | 37 lb |
| Alternate (Eldoret) | 227 lb |
| Final reserve, 30 min holding | 170 lb |
| Total required | 1,201 lb |
Fuel on board is 1,050 lb, so the aircraft is 151 lb short - about 27 minutes at the planned 340 lb/h. The plan is illegal as loaded.
Note what happens if the alternate is wrongly dropped: 30 + 737 + 37 + 170 = 974 lb, leaving only 76 lb (about 13 minutes). That is not a reserve for anything; it would be consumed by a single deviation around a CB, one hold, or a missed approach and second approach at an NDB with no radar and no lighting.
3. As PIC, what do you do about the dispatcher's position and the commercial pressure to depart?
Read the worked answer
Do not depart as loaded. The PIC has final authority over the flight and cannot delegate the decision to a dispatcher; a commercial schedule is not a defence for departing with a fuel plan that does not meet the requirement, and there is no "dispatcher's discretion" clause to hide behind.
Options, in order of preference:
- Delay to the following morning so the arrival is in daylight, which also removes the daylight-only restriction.
- Uplift fuel to at least 1,201 lb plus a realistic allowance for CB deviation and a second approach - say 1,350–1,400 lb - after confirming the strip and the alternate are still usable.
- Offload payload if the strip performance or tank capacity limits the uplift.
Record the decision and the reasoning in the flight folio and notify the operator in writing. If the operator insists on departure, the PIC's refusal stands; the correct escalation is to the operations manager and, if necessary, the Authority. A refused flight is a non-event; a fuel starvation or a night landing at an unlit strip is not.