No Radio at the Control Zone Boundary
Marc is a private pilot flying a Cessna 172 VFR at 3,500 ft, 12 NM west of a Class D control zone. The tower frequency is 118.7. He intends to land for fuel. Without warning, his radio goes silent: he can hear nothing and his transmissions are not answered. He has no handheld radio. The aircraft has a serviceable transponder. The control zone requires an ATC clearance for VFR entry. Weather is 5 SM visibility and a 3,000 ft ceiling, so VFR is not in doubt. Marc is not instrument-rated. He has 2 hours of fuel remaining, and the nearest uncontrolled aerodrome is 20 NM away. He considers entering the zone and landing without a clearance, or circling to attract light signals.
1. May Marc enter the Class D control zone without a radio clearance? Explain the reasoning.
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No. Class D control zones are controlled airspace, and VFR aircraft need an ATC clearance to enter. A clearance requires two-way radio communication. Marc has not received one and cannot receive one now, so entering the zone would be a regulatory violation and a collision risk. The correct action outside the zone is to remain clear, squawk 7600 to indicate radio failure, and divert to the nearest uncontrolled aerodrome. If he were already inside the zone when the radio failed, the situation would be different: he should continue according to his last clearance, watch for light-gun signals, and avoid sudden manoeuvres. Here, because he is still 12 NM out and has 2 hours of fuel, diversion is the safe and lawful choice.
2. If Marc diverts, what should he do with the transponder and radio, and why is circling the zone not a good plan?
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He should not circle the control zone hoping for light signals while outside; light signals are a contingency for aircraft already in the zone or for ground vehicles, not a way to obtain an initial entry clearance without radio. He should turn toward the uncontrolled aerodrome, maintain VFR, and use the transponder on 7600. If he has a cell phone and can land safely, he can call the tower after landing to explain. He should also check whether a handheld or second radio is available; if he can re-establish communications, he can request a clearance normally. Without communications, he must stay out of Class C and D airspace. The key point is that radio failure does not authorize entering controlled airspace; it requires a plan that keeps the aircraft clear and informs ATC afterward.
3. What must Marc do after landing at the uncontrolled aerodrome?
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After landing, Marc should notify the tower by telephone as soon as practical, explaining the radio failure, his position when it occurred, and his diversion. He should record the event in the journey log if required and have the radio inspected before the next flight. If the failure was caused by an equipment defect, the aircraft should not be flown again until it is repaired and a maintenance release is issued. He should also consider filing an occurrence report if the failure affected safety. The priority is to close the loop with ATC and to ensure the aircraft is not returned to service with a known communication defect.