Radio Failure in IMC on an IFR Clearance
You are the pilot-in-command of a Part 91 IFR flight from Palmerston North (NZPM) to Wellington (NZWN) in a Beechcraft Bonanza, cruising at 8,000 ft in IMC. Wellington Approach clears you for the RNAV (GNSS) RWY 34 approach, and you read back the clearance. Shortly after, your VHF radio fails completely: you can hear nothing and transmit nothing. You are 25 nm northeast of Wellington, in controlled airspace, with no mobile coverage. The aircraft has a serviceable transponder and ADS-B, and you have 90 minutes of fuel. The weather at Wellington is 800 ft overcast, 4 km visibility, and the RNAV approach minima are 620 ft and 1,200 m. There is an alternate at Paraparaumu (NZPP) with better weather, 40 nm away, but you are not familiar with its approach.
1. What are the lost-communication procedures you should follow, and why?
Read the worked answer
Select 7600 on the transponder and ADS-B, maintain the last assigned route and altitude, and continue to transmit blind calls on the appropriate frequency. In IMC, do not cancel IFR or descend VFR.
Follow the lost-communication procedure in AIP NZ: generally continue via the last acknowledged clearance and route to the destination, and carry out the approach. If in VMC, you may land VFR. The aim is to be predictable to ATC.
2. Should you continue to Wellington, divert to Paraparaumu, or take another action? Explain the judgement.
Read the worked answer
Continue to Wellington. You are already cleared for the RNAV RWY 34, the weather (800 ft/4 km) is above the minima (620 ft/1,200 m), and ATC will expect you on that clearance.
Diverting to an unfamiliar Paraparaumu without radio in IMC introduces more risk and uncertainty. At Wellington, fly the approach; if you do not become visual, follow the published missed approach and consider holding to await light signals. If fuel becomes a factor, declare an emergency and divert.
3. What transponder/ADS-B and light signals should you use?
Read the worked answer
Squawk 7600. On approach, watch for light signals from the tower:
- steady green: cleared to land;
- flashing green: return for landing;
- steady red: give way, continue circling;
- flashing red: aerodrome unsafe, do not land;
- alternating red/green: exercise extreme caution.
If no signal is received, do not land unless you can do so safely; consider a low pass or a diversion.