Radio Failure on Approach into Santa Cruz
You are inbound to Viru Viru International Airport (Santa Cruz) in a Cessna 172 on a VFR flight from Trinidad. You have been cleared to enter the control zone and instructed to report on final for runway 33. On downwind, your radio transmits but you receive no reply, and after several attempts you hear nothing on the frequency. The transponder is set to 7600 as a precaution. You are 5 nm from the threshold at 3,000 ft, the weather is CAVOK, and the tower is visible. There is other traffic in the circuit.
1. What does a 7600 transponder code signify, and what are the standard radio-failure procedures for entering a controlled aerodrome?
Read the worked answer
Setting 7600 signals a radio failure to ATC and other aircraft. The standard procedure for a radio failure in VFR conditions is to continue to the destination aerodrome, remain clear of cloud and in VMC, and join the circuit in a predictable manner. The pilot should make blind transmissions on the tower frequency stating position, altitude and intentions, and should watch for light signals from the tower. The pilot should also listen on the appropriate frequency and on the emergency frequency if equipped. At a controlled aerodrome the pilot should join the circuit on the downwind leg, conform to the pattern, and look for a green light signal authorising landing. If no signal is received, the pilot should not land without clearance unless safety requires it, and should consider diverting to an uncontrolled aerodrome.
2. How should the pilot use light signals and circuit positioning to land safely?
Read the worked answer
The pilot should position the aircraft on downwind, then base and final, while watching the tower for light signals. A steady green light means cleared to land; a flashing green means cleared to taxi; a steady red means give way and continue circling; a flashing red means aerodrome unsafe, do not land; a flashing white means return to starting point. The pilot should make blind calls on final and should keep a close watch for other traffic, since the radio failure may not be known to all aircraft in the circuit. If a green light is received, the pilot may land, but should still confirm the runway is clear. If no signal is received and fuel permits, the pilot should continue in the circuit and try again, or divert to an uncontrolled aerodrome where a normal circuit and landing can be made without clearance.
3. What communication and decision-making errors should the pilot avoid in this situation?
Read the worked answer
The pilot should avoid assuming the radio is completely failed without checking the volume, squelch, frequency and headset connections. The pilot should avoid entering the runway or landing without clearance unless an emergency requires it, and should avoid cutting across the circuit in a way that conflicts with other traffic. The pilot should not descend below a safe altitude while distracted by radio troubleshooting. Decision-making should prioritise traffic separation and predictable behaviour: fly a standard circuit, make blind transmissions, watch for light signals, and be prepared to divert. If fuel becomes a concern, the pilot should declare an emergency and land at the nearest suitable aerodrome rather than continue troubleshooting.