In-flight replanning after an engine problem and weather deterioration
You are flying a Piper Seneca from WBSB to Sibu (WBGS) at FL 110 with 4 passengers. Forty minutes after departure, the right engine shows a 15-inch manifold pressure drop, high CHT and rough running. You shut it down and feather the propeller. The aircraft now cruises at 130 kt TAS on one engine, burning 60 lb/h. You have 420 lb of fuel remaining. Sibu is 70 NM ahead; Kuching (WBGG) is 120 NM ahead; Bintulu (WBGB) is 55 NM behind. Weather at Sibu is 2 000 ft broken, 8 km visibility; at Kuching 1 500 ft broken, 6 km; at Bintulu 3 000 ft scattered, 10 km.
1. Evaluate your diversion options and recommend a course of action.
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At 130 kt, time to each airport: Sibu 70/130 h = 32 min; Kuching 120/130 h = 55 min; Bintulu 55/130 h = 25 min. Fuel burn at 60 lb/h = 1 lb/min. Remaining fuel 420 lb gives 420 min of endurance, so fuel is not the limiting factor for any option. However, single-engine performance at FL 110 is marginal: the aircraft may not maintain altitude, and a drift-down to a lower level will reduce TAS and increase fuel burn. Bintulu is the closest and has the best weather, giving the greatest margin for an asymmetric approach and possible go-around. Sibu is closer to the destination but has lower cloud. The recommended action is to divert to Bintulu, declare an emergency or urgency as appropriate, and plan a straight-in approach with a single-engine go-around briefed.
2. What human factors and decision-making traps are present in this scenario?
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The pilot may be tempted to continue to Sibu because it is the planned destination and only 70 NM ahead, a classic plan-continuation bias. There may also be reluctance to declare an emergency, fearing paperwork or embarrassment. Fatigue, workload from asymmetric flight and passenger anxiety can degrade decision-making. The correct approach is to use a structured decision model, consider the worst case (engine failure on approach or go-around), and choose the option with the greatest margin. Declaring an emergency gives priority handling and reduces workload. Passengers should be briefed and the cabin secured before the approach.