IFR Departure with Partial Panel and Alternator Failure
You are airborne in IMC on an IFR departure from a controlled airport, climbing through 3 000 ft on a SID requiring a 6% climb gradient to 5 000 ft. The alternator warning light illuminates and the ammeter shows a 20 A discharge. Within 2 min the attitude indicator begins to tumble and the horizontal situation indicator flags. You still have the standby attitude indicator, airspeed, altimeter, turn coordinator, and magnetic compass. The cloud tops are reported at 6 000 ft and the minimum vectoring altitude is 4 500 ft. ATC has not yet been advised. You have 45 min of battery endurance at current load and the destination is 40 NM away with an ILS.
1. Prioritize your actions in the first 60 seconds and explain the reasoning behind the order.
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First 60 seconds - aviate, navigate, communicate:
- Aviate: Maintain aircraft control on partial panel using the standby attitude indicator, airspeed, altimeter, and turn coordinator. Establish a stable climb or level-off and trim. Do not chase the failed instruments.
- Navigate: Confirm position and the SID track. The 6% climb gradient may no longer be achievable with degraded instrumentation, so request a level-off or a lower climb gradient if terrain permits. Cross-check the minimum vectoring altitude of 4 500 ft.
- Communicate: Advise ATC of the alternator failure and partial panel, and request vectors to VMC or an ILS approach. State battery endurance.
- Manage the system: Reduce electrical load (landing light, pitot heat if not required, unnecessary avionics) to extend battery life. Attempt an alternator reset per the checklist only if it does not distract from control.
Reasoning: Loss of the attitude indicator in IMC is a critical failure; control must be established before troubleshooting. ATC notification unlocks priority handling and lower workload. Load shedding directly extends the time available to reach VMC or an approach.
2. Decide whether to continue to the destination ILS or divert, and justify using battery endurance, weather, and instrument status.
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Decision: request vectors to VMC or the nearest suitable airport, not the original destination, unless VMC is reached quickly.
- Battery: 45 min at current load, but load shedding may extend this to 60 min. The destination is 40 NM away; at 100 kt that is 24 min plus an approach of about 10 min, leaving little margin if a missed approach is required. A missed approach on partial panel with a failing battery is high risk.
- Weather: Cloud tops at 6 000 ft mean VMC may be reachable by climbing, but the aircraft is at 3 000 ft and the climb gradient is in doubt. If VMC is reached, the risk drops sharply and a visual approach to the destination may be acceptable.
- Instruments: With only a standby attitude indicator and turn coordinator, an ILS is flyable but demanding. A diversion to an airport with better weather and a longer runway reduces workload.
- Action: Advise ATC, request the nearest VMC or a diversion airport with an ILS and good weather. If VMC is reached, reassess; otherwise land at the diversion. Declare an emergency if battery voltage falls below the minimum for essential instruments.