Interception
Interception by military aircraft occurs when a civilian flight is unknown or suspicious — e.g. when no flight plan is filed, radio failure, or the aircraft deviates in protected airspace.
Source: ICAO Annex 2 Appendix 1+2 Interception of Civil Aircraft; ICAO Doc 9554 Manual on Implementation of a 300m (1000ft) Vertical Separation Minimum (for VSM context); ICAO Annex 11.
When does interception occur?
- Unidentified traffic in restricted airspace (e.g. ADIZ).
- Radio failure without squawk 7600 → ATC alerts military.
- Squawk 7500 (hijack).
- Deviation from assigned route without explanation.
- Drones / UAVs without authorisation.
Interception procedure
Standardised by ICAO Annex 2 Section 3.8 + Appendix 1+2.
Phase 1: Identification
- Military aircraft approaches.
- Position: typically left and slightly above the civil aircraft.
- Visible signal given.
Phase 2: Standard signals from interceptor
Pilot (interceptor) signals via:
| Signal | Meaning |
|---|---|
| Wing rocking + position lights flashing | "You have been intercepted, follow me." |
| Turn left (standard turn) | "Follow me." |
| Acceleration + climb + tail lights flashing | "You may proceed" (cleared away) |
| Wing rocking + lights on + tail down | "Land at this airport." (with follow-up turn) |
Phase 3: Responses by intercepted pilot
| Pilot reaction | Meaning |
|---|---|
| Wing rocking | "Understood, will comply." |
| Steady lights + tail lights flashing | "Cannot comply." |
| Lights flashing regularly + tail lights off | "In distress." |
| Lights flashing irregularly | "Hijacked / unable to communicate." |
Radio communication during interception
- Try contact on 121.500 MHz (emergency).
- Try contact on the frequency the interceptor specifies (e.g. 121.500 or military frequency).
- If radio works: identify with callsign, position, intentions.
Standard "Follow Me" instruction
Interceptor: wing-rocking + left turn.
- Pilot follows with same turn direction, lower speed.
- Distance: about 200 m behind and slightly above interceptor.
- With multiple interceptors: pilot follows the leading one.
Re-routing
Interceptor can instruct to:
- Land at a specific aerodrome.
- Take a different altitude.
- Fly a different route.
Pilot must cooperate — even when instructions seem incomprehensible.
Pilot behaviour
What to do during interception?
- Stay calm — no sudden manoeuvres.
- Wing-rock back → "understood, will comply".
- Follow, don't evade.
- Try radio contact on 121.500.
- Identify: callsign, flight plan, position.
- Comply with instructions — even with understanding problems.
- After landing: identity check by military/police.
Things NOT to do
- Don't try to evade — can be interpreted as a threat.
- Don't fly away without explanation.
- Don't perform aggressive manoeuvres.
- Don't set squawk 7500 by chance → interpreted as hijack.
Special case: civilian crossing ADIZ
ADIZ (Air Defense Identification Zone) is an extended airspace where all flights must be identified:
- USA ADIZ: Atlantic, Pacific, Mexico border, Alaska.
- Russia ADIZ: wide areas.
- China ADIZ: East China Sea.
On entry: pilot must file flight plan in advance and establish radio contact, otherwise interception risk.
Historical incidents
Tragic examples:
- KAL 007 (1983): Korean Airlines Boeing 747 shot down by Soviet Sukhoi Su-15 over Sakhalin.
- El Al 4X-AXG (1973): Israeli Boeing 707 shot down by Libyan Mirage III over Sinai.
- Iran Air 655 (1988): A300 shot down by US Navy USS Vincennes over Persian Gulf (identification error).
Sources: ICAO Investigation Reports.
Cross-reference
- Subject 010 Lesson "Airspaces": ADIZ definition.
- Subject 090 Lesson "Hijack": specific hijack squawk code.