Radio failure in IMC: applying the lost-communication procedure
You are the sole pilot of a Piper PA-34 Seneca on an IFR flight from Lagos (DNMM) to Kano (DNKN), level at FL190 in instrument meteorological conditions. At 1405Z, 60 NM south of Kano, the controller clears you: "Five November Alpha, maintain FL190, direct Kano VOR, expect further clearance at 1435." At 1407Z the number one VOR/ILS receiver fails, and while you are troubleshooting it the audio panel dies: you can neither transmit nor receive. You are still in cloud, OAT is minus 8 degrees C, and your only working aids are the number two VOR and a panel-mount GNSS receiver. Your filed flight plan shows Kano as destination with an ETA of 1428 and Kaduna as alternate. At 1407Z you calculate fuel endurance as 2 hours 10 minutes. The transponder is on code 4271 with altitude encoding. Kano is reported 700 ft broken, 3 km in rain, wind calm.
1. What are your immediate actions after the radio failure, and what level and speed must you maintain, and for how long?
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Immediate actions
- Fly the aeroplane first - hold FL190, trim, and check fuel and engine parameters before troubleshooting.
- Select 7600 on the transponder and keep altitude encoding on. This is the signal ATC looks for when a clearance is no longer being read back.
- Try every means of restoring contact: second radio, 121.5, the voice feature of a VOR, relay through another aircraft, a company frequency, and after landing a telephone call to the ATS unit.
- Squawk, lights on, and keep a listening watch on whatever receiver still works.
Level and speed
The standard rule is to maintain the last assigned level and speed for 7 minutes after the failure - here from 1407Z to 1414Z - because the controller is still separating you on the assumption that you are flying the last clearance. If the failure had occurred in a holding pattern, the period is 2 minutes. At 1414Z you may then adjust to the level and speed filed in the flight plan; FL190 is already your filed cruising level, so in practice you remain at FL190.
Why it matters
Climbing or descending early creates a conflict with traffic the controller believes is separated from you. The 7-minute rule is not a suggestion; it is the vertical buffer the system relies on.
2. When may you leave the Kano VOR holding fix, and how do you conduct the route and descent from that point? What changes if no EFC had been given?
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Leaving the clearance limit
Your clearance limit is the Kano VOR, and you have an explicit EFC of 1435Z. You must not leave the fix before 1435Z, whatever your ETA shows, because ATC may be holding other traffic through that fix. At 1435Z you may leave and descend.
Route and descent after leaving
- Route: by the last assigned route (direct Kano VOR), then as filed.
- Level: fly the minimum IFR altitude for the segment being flown; in IMC you must not descend below the minimum IFR altitude except on a published approach procedure.
- Then fly the published VOR/DME approach, descending only on the published segments, and not below the MDA until visual.
If no EFC had been issued
You would leave the clearance limit at the ETA calculated from your flight plan - here 1428Z - rather than at a controller-assigned time.
Practical point
With 2 hours 10 minutes of fuel at 1407Z, holding to 1435Z costs about 28 minutes plus the approach. That still leaves over an hour, so comply with the EFC rather than pushing on; if holding had to be much longer, fuel would become the deciding factor and a diversion would be the correct call.
3. You arrive at the Kano VOR at 1435Z with 1 hour 20 minutes of fuel remaining and learn (from ATIS or from another aircraft's transmissions you overhear) that Kano has gone down to a 200 ft ceiling and 800 m visibility. Kaduna is 45 NM away and reported 1,500 ft broken, 8 km. What is your decision process?
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What the rules allow
The lost-communication procedure obliges you to continue in accordance with your clearance and flight plan, but it does not require you to fly an approach into weather below the minima. Descending below the published minima would be a breach of the IFR rules; the correct course is to land at the nearest suitable aerodrome, taking advantage of the emergency provision that allows you to deviate from the clearance where it is necessary to do so safely.
Decision process
- Establish the facts: ceiling and visibility versus the VOR/DME minima at Kano. At 200 ft and 800 m the approach is not available to you.
- Fuel: 1 hour 20 minutes. Kaduna is 45 NM, roughly 19 minutes at 140 kt ground speed in the descent, leaving about an hour on arrival there.
- Weather: Kaduna at 1,500 ft broken and 8 km is comfortably above minima.
- Terrain and minimum IFR altitudes on the Kaduna routing must be checked before descending.
- Keep squawking 7600, and if a receiver works, listen for other traffic and for ATC instructions; nobody will expect you at Kano if you appear overhead Kaduna, so plan for the possibility of a visual approach or a straight-in after establishing contact.
Set a limit
Do not orbit over Kano hoping for an improvement. Fix a fuel figure below which you will abandon Kano regardless and proceed to Kaduna.