Interception after an unnoticed prohibited area
On a clear summer morning a private pilot in a Cessna 182 flies VFR from State A to State B under a filed flight plan, cruising at 4,500 ft AMSL over mountainous terrain. Forty miles before destination the GPS fails; he continues by dead reckoning and drifts about 12 nm off track. He does not know that a circular prohibited area of 3 nm radius around a nuclear power station inside State B is active by NOTAM - he has not checked NOTAMs for two days. A voice on the radio warns him, but before he can act two fighter aircraft appear. The first takes station on his left, rocks its wings from level flight, and he follows. The second aircraft then circles the aerodrome ahead and lowers its landing gear while overflying the runway. His aircraft carries no transponder. He has 2 h 30 min of fuel and the weather is CAVOK, but the terrain rises to 6,000 ft within 5 nm of his track.
1. Identify each signal the interceptors give and the response the pilot must make, including the radio actions.
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These are the interception signals of Annex 2, Appendix 1, and they are a sequence with different meanings. The interceptor's manoeuvre, not the pilot's expectation, determines which signal is being given.
- Rocking the wings from level flight, stationed to the left of the intercepted aircraft: 'You have been intercepted, follow me.' The response is to rock the wings in acknowledgement ('understood, will comply') and follow the interceptor, keeping it in sight.
- Circling the aerodrome and lowering the landing gear while overflying the runway: 'Land at this aerodrome.' The response is to lower the landing gear, follow, and land behind the interceptor. If the pilot could not comply with a landing instruction, the recognised response is to keep the gear retracted while continuing to circle.
Radio actions run in parallel:
- Attempt contact with the interceptor on 121.5 MHz, giving identity, position and intentions in plain language.
- Notify ATS if able, and broadcast on the appropriate frequency in case the call is heard by the warning voice or by ATC.
- Select code 7700 if a transponder is fitted, unless the interceptor or ATC instructs otherwise; with no transponder, radio and visual signals carry the entire burden of communication.
- Continue to monitor 121.5 and keep the interceptor in sight until released, watching for the break-away signal (a climbing turn of 90 degrees or more away from the aircraft), which means 'you may proceed'.
Failing to respond to the signals is itself an infringement and invites escalation, including being forced to land.
2. The pilot fears that following the interceptor would take him towards high ground. What are his obligations, and how should he reconcile compliance with safety?
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Compliance with the interceptor's instructions is mandatory, but the commander remains responsible for the safety of the aircraft, and the interception procedure is built on that assumption: the interceptor is required to take account of the intercepted aircraft's performance and limitations, including its inability to climb or descend sharply.
Given terrain rising to 6,000 ft within 5 nm and the aircraft at 4,500 ft, a turn towards high ground or a descent may be unsafe. The correct sequence is:
- Comply promptly and visibly with the initial instruction where it is safe to do so - this establishes that the pilot has understood and is not a threat.
- If the instruction cannot be flown safely, do not simply ignore it. Broadcast on 121.5 MHz in plain language, for example 'Terrain ahead, unable to descend, request climb on present heading', so the interceptor knows the problem immediately.
- Use the visual response available in the landing series (keeping the landing gear retracted while continuing to circle) if the instruction is to land and it cannot be complied with.
- Climb only when it does not conflict with the interceptor's manoeuvre, and continue to watch for the break-away.
- If the situation becomes unsafe, declare an emergency (MAYDAY) on 121.5 MHz, and report the occurrence to ATS after landing.
The safety of the aircraft prevails over blind compliance. The pilot is not entitled, however, to use terrain as a reason for ignoring the interception altogether; he must communicate, cooperate and be seen to be cooperating.
3. After landing, State B's police propose a fine and wish to search the aircraft. What is the legal position of the pilot and the aircraft under the Convention?
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State B's own rules govern the flight. Article 11 makes the laws and regulations of a contracting state relating to the flight and manoeuvre of aircraft applicable to all aircraft in its territory, without distinction of nationality, provided they are published; Article 12 makes compliance with the rules of the air mandatory. Flying into an active prohibited area is an infringement of State B's published regulations, and navigational error is not a defence in itself.
The pilot's position is weak on the merits: he had not checked NOTAMs for two days and continued on dead reckoning in mountainous terrain without a positive fix. That will be characterised as at least negligent, and State B may act under its national law by fine or prosecution, and may take action in respect of the licence in accordance with its own procedures. State A may also act, because a licence holder must comply with the rules of the air wherever they fly.
On the aircraft, Article 16 gives the authorities of each contracting state the right, without unreasonable delay, to search aircraft of other contracting states on landing or departure and to inspect the certificates and other documents prescribed by the Convention. Detention is possible for reasons of aviation safety, but the Convention also requires states to deal with aircraft expeditiously and not to delay them unduly; detention is not available as a debt-collection device for the fine.
Cooperating fully, producing the documents, and reporting the navigational failure promptly will affect penalty and enforcement discretion. They do not remove the infringement.