Interception of civil aircraft

Recognise and respond

Interception should be a last resort for identification and safety.

Immediate response

Interception may arise from an unidentified or strayed aircraft, unauthorised entry or security concern. Follow and interpret the intercepting aircraft’s visual signals, notify the appropriate ATS unit if possible, attempt contact on 121.5 MHz with identity and nature of flight, and select 7700 unless otherwise instructed by ATS. If contact fails, repeat on 243 MHz if practicable.

If radio instructions conflict with the interceptor’s visual instructions, seek immediate clarification while continuing to comply with the visual instructions. Do not improvise a threatening approach toward the interceptor. Maintain the appropriate safe aircraft control and terrain awareness.

The first signals

The interceptor rocks wings and flashes navigation lights at irregular intervals, normally from slightly above and ahead to the left, then makes a slow level turn to indicate the desired heading: “You have been intercepted; follow me.” The intercepted aircraft rocks wings, flashes navigation lights at irregular intervals and follows. An abrupt climbing breakaway of 90 degrees or more without crossing the intercepted aircraft’s line of flight means “You may proceed”.

Gear lowered, steady landing lights and overflight of the runway in use indicate “Land at this aerodrome”; the intercepted aircraft responds by lowering gear, showing steady landing lights and following, then landing if considered safe. The complete Appendix 2 includes signals for an unsuitable aerodrome, inability to comply and distress. The visual viewer distinguishes these signals rather than treating every wing rock as the same message.

Keep the message unambiguous

Standard phrases help when a common language is unavailable.

Use short standard messages

The interceptor may use CALL SIGN, FOLLOW, DESCEND, YOU LAND, PROCEED and the standard acknowledgment WILCO. The intercepted pilot can use CALL SIGN with identity, WILCO, CAN NOT, REPEAT, AM LOST, MAYDAY, HIJACK, LAND with a place, and DESCEND as prescribed. Their purpose is a short exchange of identity and intent, not a lengthy negotiation on a congested frequency.

An unsuitable designated landing aerodrome is indicated by the prescribed gear/landing-light and pass-over actions; inability to comply and distress have different light signals. A pilot should use the correct complete signal and continue attempts to clarify by radio. Learn the visual signal and its acknowledgment as a pair.

Resolve the conflicting instruction

An ATS instruction that appears inconsistent with the interceptor is a reason to request clarification immediately. Meanwhile comply with the interceptor’s visual instructions as the rule specifies. Report the interception to the relevant authority under the applicable procedures after the immediate situation is safe.

The intercepting aircraft should avoid wake hazards and unnecessary manoeuvring. This lesson’s synthetic scene illustrates recognition and sequencing only; it is not a tactical model of military aircraft performance.

Can you apply the rules?

Four original questions. Choose from the facts, then review the explanation.