Last Sector to Marawaka: Fuel, Duty and a Chief Pilot's Pressure
You are the sole pilot of a Cessna 208B operated by Highland Charters Ltd under its PNG Part 135 certificate from Goroka (AYGA). It is 1525 on Friday. Your duty began at 0545 and you have flown four sectors totalling 5 h 20 min, with one 40-minute break at Wewak. The last task is Goroka–Marawaka (AYMW) with seven passengers and 300 kg of freight, then an empty return after a 30-minute turnaround. Marawaka is an unlit, VFR-only gravel strip in a valley; the company exposition forbids night operations there and requires 45 minutes final reserve plus a 20-minute alternate allowance to Goroka. Fuel on board gives 1 h 35 min at planned consumption; the round trip is planned at 1 h 05 min. The 1500 forecast gives TEMPO thunderstorms, cumulonimbus to FL250, and broken cloud at 2 000 ft after 1600, lowering to 1 200 ft by 1700. Sunset is 1812. The chief pilot messages: 'The mine needs those parts tonight. Go.'
1. Work through the go/no-go decision systematically. What constraints apply, how do they interact, and what is your conclusion?
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Run the check in an order that lets a single disqualifier end the analysis, then test the rest for compounding risk.
1. Fuel. Required endurance = 1 h 05 min trip + 20 min alternate allowance + 45 min final reserve = 2 h 10 min. Available is 1 h 35 min. The flight fails on fuel alone. Note that the alternate allowance is not optional here: the TEMPO thunderstorm and lowering cloud make a destination alternate mandatory, and the empty return leg would still be flown in the same fuel state.
2. Day/night and strip qualification. The exposition prohibits night operations at Marawaka and the strip is unlit and VFR-only. Even with an on-time departure the turnaround and return put you past 1812 sunset; unforecast delays of the sort thunderstorms produce are the norm, not the exception. This is a second independent disqualifier.
3. Flight and duty time. Duty began 0545. Add ~2 h 40 min of flying and ground time and you finish around 1830–1900 - a duty of roughly 12 h 45 to 13 h 15 after an already demanding day. The prescriptive flight and duty limits applicable to Part 135 operations, mirrored in the exposition, are unlikely to permit this, and cumulative fatigue after 5 h 20 min in highland terrain is a real performance issue, not a paperwork one.
4. Weather and terrain. A valley strip with no instrument approach, forecast CB activity to FL250 and cloud base falling to 1 200 ft leaves no margin for a missed approach or a go-around in a confined valley.
Conclusion: the flight cannot legally depart and would not be safe. The correct answer to the chief pilot is a clear 'no', with the fuel and night figures quoted so the refusal is evidence-based rather than a matter of opinion.
2. The chief pilot replies that he is the accountable manager, that he will 'note the decision in the ops file as a management override', and that the company will carry the risk. Who has final authority, and what are your responsibilities and protections?
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The suggestion that a manager can assume the decision is wrong in law and in practice.
Final authority. Under Part 91 (and the equivalent operating rules in Parts 121, 125 and 135), the pilot in command is responsible for the operation and safety of the aircraft and has final authority over its disposition. Nothing in the exposition, the AOC or a management instruction displaces that. A management override documented in an ops file does not transfer the decision; it may instead become evidence that the operator pressured a crew to breach the rules.
Operator obligations. The certificate holder must ensure that flights are planned and conducted within the rules and within its exposition, and must not direct a crew to act contrary to them. An operator whose scheduling system routinely produces non-compliant tasks has a systemic problem that the regulator will treat as an organisational failure, not a pilot failure.
Your responsibilities. Refuse, record the refusal factually and contemporaneously (time, the figures that made it non-compliant, who directed what), and notify the passengers and operator so they can make alternative arrangements. Do not agree to 'just the first sector' - partial compliance does not fix a fuel or night limitation.
Protections and escalation. Internal safety reporting to the operator's SMS, and if pressure continues, a report to CASA PNG as regulator. Many states also operate a confidential reporting channel for exactly this situation. Keep it factual and keep a copy off the company server.
3. Assume instead that fuel had been adequate and you had departed. On arrival at Marawaka cloud base is 900 ft and rain is falling in the valley. What are your options and what are the legal limits on descent?
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The overriding rule is that you must remain in visual meteorological conditions; there is no instrument approach at Marawaka and no controlled airspace or ATS unit to issue a clearance, so no amount of 'local knowledge' creates a legal descent path below the VFR minima.
Legal limits. Minimum height for VFR flight is 500 ft above the surface (higher over congested areas and obstacles), and you must maintain the prescribed flight visibility and cloud separation, which at these altitudes is 5 km visibility with 1 500 m horizontally and 1 000 ft vertically clear of cloud. A 900 ft base in rain in a valley is unlikely to permit either, so a descent into the valley would be unlawful and - more importantly - unrecoverable in rising terrain.
Options, in order of preference. Hold in VMC over the valley entrance or a safe area to the north and reassess with the latest actual weather; divert to the alternate you nominated (Goroka); or return to Goroka. Communicate the diversion to the operator and, where radio coverage permits, to ATS so the flight is not treated as missing or overdue, and so that the company can make the passenger arrangements.
If fuel becomes critical. Declare an emergency (MAYDAY) and land at the nearest suitable site, but recognise that this does not retrospectively legalise a descent made earlier: an emergency declared solely because you pressed on into known non-VFR conditions will be examined in that light.
The real lesson. The decision point was on the ground at Goroka. Arriving over a valley strip with a TEMPO of thunderstorms and a 1 h 35 min fuel state converts a manageable no-go into an in-flight emergency. Set a bingo point and commit to the diversion before you need to.