Interception of civil aircraft
Learning objectives
- State the actions required of the pilot of an intercepted aircraft, including radio frequency and transponder code.
- Interpret the interceptor's three signal series (follow me, you may proceed, land here) and state the correct response to each.
- State the signals the intercepted aircraft can initiate: aerodrome inadequate, cannot comply and distress.
- State what to do when a radio instruction conflicts with the interceptor, and which phrases to use when there is no common language.
The idea
Being intercepted means that another aircraft, usually military, has come up beside you because someone on the ground wants to know who you are or needs you out of the place you are in. It is rare, it is meant to be a last resort, and it is not a punishment. What makes it safe is that both pilots know the same script: where the interceptor appears, what its signals mean, and how you answer. The one rule to hold onto is that while you are being intercepted, you follow the interceptor and ask questions afterwards.
What interception is, and its limits
Apart from intercept and escort service given on request, interception of civil aircraft is governed by Member States' own regulations and administrative directives. They are issued in line with the Chicago Convention, under which States must have due regard for the safety of navigation of civil aircraft when regulating their State aircraft.
Guidance addressed to States says national rules should ensure that interception is only a last resort. It should be limited to identifying the aircraft, unless it is necessary to return the aircraft to its planned track, direct it beyond national airspace, guide it away from a prohibited, restricted or danger area or congested areas, or instruct it to land at a designated aerodrome. Practice interceptions are only done if agreed in advance with the PIC, with ATC told. A designated landing aerodrome should be suitable for the aircraft type. States should also publish a standard method for manoeuvring interceptors, designed to avoid any hazard to the intercepted aircraft.
Avoiding interception
The best defence is not to be a surprise. A flight plan is required for any flight in or into areas or along routes designated by the competent authority to facilitate coordination with military units or adjacent States' ATS units, "in order to avoid the possible need for interception for the purpose of identification". Flight plans are taught on page 030-11-01. When an ATS unit has located a strayed aircraft, it advises the aircraft of its position and corrective action, immediately if it knows there is a possibility of interception or other hazard. Prohibited areas and areas needing special authorisation should be clearly published in the AIP, together with any risk of interception if entered. The areas themselves are taught on page 010-05-02, and airspace classes and infringements on page 010-07-01.
Plan around published areas, check NOTAMs and use the flight information service. If a second radio or a standby monitor function is available, listen on 121.5 MHz near prohibited or restricted areas or national borders, so that an interceptor's call can reach you.
What the interceptor is expected to do
The guidance tells you what to expect, in three phases of visual identification.
- Phase I: the interceptor approaches from astern. The leader, or a single interceptor, normally takes up a position on the left, slightly above and ahead, within your field of view, initially no closer than 300 m. Other interceptors stay well clear, preferably above and behind.
- Phase II: the leader closes in gently at the same level, no closer than necessary, avoiding startling the crew or passengers.
- Phase III: the leader breaks gently away in a shallow dive, and the others rejoin.
For navigational guidance the interceptor takes position on the left, slightly above and ahead, so you can see its signals, and it must be satisfied that you are aware and acknowledge. Weather or terrain may put it on the right side, where it must stay clearly visible. The interception method must account for civil aircraft performance limits and avoid wake turbulence hazards, particularly if the intercepted aircraft is a light aircraft. An intercepted aircraft with ACAS may get a resolution advisory against the interceptor, so interceptors with SSR transponders should suppress pressure-altitude reporting within at least 37 km (20 NM) of the intercepted aircraft. Tracer bullets to attract attention are hazardous, and measures are expected to avoid their use.
Guidance to interceptors on landing says that care must be taken not to lead the aircraft into conditions below VMC, that if made to land the aerodrome and surrounding terrain should be suitable and the aircraft must have enough fuel, and that "only the pilot-in-command of the civil aircraft can judge the safety of the landing operation in relation to runway length and aircraft mass at the time".
Describe this figure
Four panels are stacked from top to bottom, each seen from above with the light aeroplane's nose pointing up. Panel 1, Phase I: the interceptor approaches from astern and takes a position on the left, slightly above and ahead of the light aeroplane, initially 300 m or more away. Panel 2, Series 1: the interceptor rocks its wings and flashes its navigation lights at irregular intervals, meaning follow me; the light aeroplane answers the same way, meaning understood, will comply. Panel 3: the interceptor makes a slow level turn, normally to the left, and the light aeroplane follows. Panel 4, Series 2: the interceptor makes an abrupt climbing turn of 90 degrees or more away, without crossing the light aeroplane's line of flight, meaning you may proceed; the light aeroplane rocks its wings.
The storyboard has four panels, seen from above with the light aeroplane's nose pointing up. Panel 1, approach and position: a fighter silhouette approaches from astern, then sits above, ahead and to the left, labelled "300 m or more initially". Panel 2, Series 1: the fighter rocks its wings with irregular navigation-light flashes, and the light aeroplane answers the same way. Panel 3, following the interceptor: the fighter makes a slow level turn and the light aeroplane follows. Panel 4, Series 2 release: the fighter makes an abrupt climbing turn of 90° or more away, not crossing the light aeroplane's path, and the light aeroplane rocks its wings.
Your first actions when intercepted
The pilot of an intercepted aircraft: follows the intercepting aircraft's instructions at once, interpreting and answering its visual signals; notifies the appropriate ATS unit if possible; tries to establish radio contact with the interceptor or the intercept control unit with a general call on 121.5 MHz, giving identity and the nature of the flight, repeating on 243 MHz if there is no contact and it is practicable; selects Mode A Code 7700 if fitted with an SSR transponder, unless the ATS unit instructs otherwise; and, if fitted with ADS-B or ADS-C, selects the appropriate emergency function if available, unless the ATS unit instructs otherwise.
| Done | Step | What to do | Reference |
|---|---|---|---|
| 1. Follow | Follow the interceptor’s instructions at once. Read its visual signals and answer them (Tables S11-1 and S11-2). | SERA.11015(b)(1) | |
| 2. Tell ATS | Notify the appropriate ATS unit, if possible. | SERA.11015(b)(2) | |
| 3. Call 121.5 | Try to reach the interceptor or the intercept control unit with a general call on 121.5 MHz, giving identity and nature of flight. If there is no contact and it is practicable, repeat on 243 MHz. | SERA.11015(b)(3) | |
| 4. Squawk 7700 | If you have an SSR transponder, select Mode A code 7700, unless the ATS unit instructs otherwise. | SERA.11015(b)(4) | |
| 5. ADS-B emergency | If you have ADS-B or ADS-C, select the appropriate emergency function if available, unless the ATS unit instructs otherwise. | SERA.11015(b)(5) | |
| 6. Conflict? Ask | If other instructions conflict with the interceptor’s visual signals or radio instructions, ask for immediate clarification and keep following the interceptor’s. | SERA.11015(c), (d) | |
| Aircraft-specific: many light aeroplanes have no 243 MHz capability, and whether an ADS-B emergency function exists depends on the avionics. Check the POH/AFM and avionics supplements. | |||
Describe this figure
The checklist has six rows, each with a tick box, a step name, what to do and the rule reference. First, follow the interceptor's instructions and answer its visual signals; second, notify the ATS unit if possible. Third, call on 121.5 MHz with identity and nature of flight, repeating on 243 MHz if there is no contact and it is practicable. Fourth, select Mode A code 7700 and fifth, the ADS-B or ADS-C emergency function if fitted, unless ATS instructs otherwise. Sixth, if instructions conflict, ask for clarification and keep following the interceptor. A note says to check the POH and avionics supplements for 243 MHz and ADS-B emergency capability.
The checklist runs in order: follow the visual signals, tell ATS if possible, call on 121.5 MHz with identity and nature of flight (243 MHz if practicable), squawk 7700 unless ATS says otherwise, select ADS-B emergency if available, and if instructions conflict, ask for clarification while still obeying the interceptor.
Most light aeroplanes have no 243 MHz capability and many have fixed landing gear. Whether an ADS-B emergency function exists, and how to select it, depends on your avionics. The rule's own wording ("if practicable", "if fitted", "if available") allows for this. Check your aircraft's POH/AFM and avionics supplements.
Transponder codes in general are taught on page 010-06-02, and radio distress procedures on page 090-05-01. The use of 121.5 MHz is limited to emergency purposes by the Member States.
When instructions conflict
If radio instructions from any source conflict with the interceptor's visual signals, you ask for immediate clarification while continuing to follow the interceptor's visual instructions. If they conflict with the interceptor's radio instructions, you ask for immediate clarification while continuing to follow the interceptor's radio instructions. The interceptor wins over other sources, ATC included, while clarification is sought.
The interceptor's signals and your answers
All of these apply to aeroplanes, day or night. The signals for helicopters differ and are not taught here.
Series 1: "You have been intercepted. Follow me." The interceptor rocks its wings and flashes its navigation lights at irregular intervals from a position slightly above and ahead of, and normally to the left of, you. After you acknowledge, it makes a slow level turn, normally to the left, onto the desired heading. You answer by rocking your wings, flashing your navigation lights at irregular intervals, and following. That means "Understood, will comply." Weather or terrain may make the interceptor take the opposite position and turn the other way. If you cannot keep pace, the interceptor is expected to fly a series of race-track patterns and rock its wings each time it passes you.
Series 2: "You may proceed." The interceptor makes an abrupt breakaway: a climbing turn of 90° or more without crossing your line of flight. You answer by rocking your wings.
Series 3: "Land at this aerodrome." The interceptor lowers its landing gear (if fitted), shows steady landing lights and overflies the runway in use. You lower your landing gear (if fitted), show steady landing lights and follow it. If, after overflying the runway in use, landing is considered safe, you proceed to land.
Older books show different details for the Series 1 answer and for Series 3. The SERA wording is the rule in force: day or night, rock wings, flash navigation lights irregularly and follow; for Series 3, gear down if fitted, steady landing lights and an overflight of the runway.
Signals you can start
Series 4: "Aerodrome you have designated is inadequate." You raise your landing gear (if fitted) and flash the landing lights while passing over the runway in use at a height of more than 300 m (1 000 ft) but not more than 600 m (2 000 ft) above aerodrome level, and keep circling the runway in use. If you cannot flash landing lights, flash any other lights. The interceptor has two replies. To lead you to an alternate aerodrome, it raises its gear (if fitted) and uses the Series 1 signals, meaning "Understood, follow me". To release you, it uses the Series 2 signals, meaning "Understood, you may proceed".
Describe this figure
A side view shows the aerodrome level as a ground line with the runway in use. A band is shaded from 300 m (1 000 ft) up to 600 m (2 000 ft) above aerodrome level, with dotted limit lines. A light aeroplane flies in the band over the runway, with a flash symbol at the nose for flashing landing lights and a note that the gear is up if fitted, and a circular arrow shows that it keeps circling the runway. Below, the interceptor has two possible replies. Series 1 signals, with the gear raised if fitted, mean understood, follow me, and lead you to an alternate aerodrome. Series 2 signals mean understood, you may proceed, and release you.
The side view shows the runway line, the aerodrome level datum, and a band shaded between 300 m (1 000 ft) and 600 m (2 000 ft) above it. A light aeroplane passes over the runway with flashing landing lights and "gear up (if fitted)", then circles. Two branches show the interceptor's replies: Series 1 for an alternate aerodrome, or Series 2 for "you may proceed".
Series 5: "Cannot comply." You switch regularly on and off all available lights, in a way distinct from flashing lights. The interceptor answers with the Series 2 signals, meaning "Understood".
Series 6: "In distress." You flash all available lights irregularly. The interceptor again answers with the Series 2 signals, meaning "Understood".
A memory aid: regular on and off means "cannot comply", irregular means "distress", and irregular navigation-light flashing together with wing rocking is the Series 1 acknowledgement, "will comply".
Describe this figure
Three timelines of light pulses run top to bottom, each with a raised bar for lights on and a flat line for lights off. The first shows uneven navigation-light flashes together with a wing rock, the Series 1 answer, meaning understood, will comply. The second shows all available lights switched on and off in equal steps, Series 5, meaning cannot comply. The third shows uneven bursts of all available lights, Series 6, meaning in distress. A time arrow runs along the bottom.
The strip shows three timelines of light pulses: irregular navigation-light flashes with a wing rock (will comply), evenly spaced on and off of all lights (cannot comply), and irregular flashing of all lights (distress).
| Series | Signals first | Signal | Meaning | Reply by the other aircraft | Meaning of the reply |
|---|---|---|---|---|---|
| Series 1 | Interceptor | Rocks its wings and flashes its navigation lights at irregular intervals, from slightly above and ahead of you, normally on your left. After you acknowledge, a slow level turn, normally to the left, onto the desired heading. | “You have been intercepted. Follow me.” | You: rock your wings, flash navigation lights at irregular intervals and follow. | “Understood, will comply.” |
| Series 2 | Interceptor | Abrupt breakaway: a climbing turn of 90° or more, without crossing your line of flight. | “You may proceed.” | You: rock your wings. | “Understood, will comply.” |
| Series 3 | Interceptor | Lowers landing gear (if fitted), shows steady landing lights and overflies the runway in use. | “Land at this aerodrome.” | You: lower landing gear (if fitted), show steady landing lights and follow. If landing is safe after the overflight, land. | “Understood, will comply.” |
| Series 4 | You | Raise landing gear (if fitted) and flash landing lights (or any other lights) while passing over the runway in use at more than 300 m (1 000 ft) but not more than 600 m (2 000 ft) above aerodrome level. Keep circling the runway. | “Aerodrome you have designated is inadequate.” | Interceptor: to lead you to an alternate, raises its gear (if fitted) and uses Series 1 signals. To release you, uses Series 2 signals. | “Understood, follow me.” or “Understood, you may proceed.” |
| Series 5 | You | Regularly switch all available lights on and off, in a way distinct from flashing lights. | “Cannot comply.” | Interceptor: Series 2 signals. | “Understood.” |
| Series 6 | You | Flash all available lights at irregular intervals. | “In distress.” | Interceptor: Series 2 signals. | “Understood.” |
| Series 1 notes: weather or terrain may put the interceptor on your right, turning the other way. If you cannot keep pace, it is expected to fly race-track patterns and rock its wings each time it passes you. | |||||
Describe this figure
The table has one row per series, with columns for who signals first, the signal, its meaning, the reply by the other aircraft and the meaning of that reply. Series 1 to 3 start with the interceptor: follow me, you may proceed, and land at this aerodrome; you answer by rocking wings and flashing navigation lights and following, rocking wings, or gear down and steady landing lights, and each answer means understood, will comply. Series 4 to 6 start with you: raise gear and flash landing lights over the runway at more than 300 m but not more than 600 m above aerodrome level while circling, meaning aerodrome inadequate; regular on and off of all lights, meaning cannot comply; irregular flashing of all lights, meaning in distress. The interceptor replies to Series 4 with Series 1 signals to lead you to an alternate or Series 2 signals to release you, and to Series 5 and 6 with Series 2 signals meaning understood. A note covers the interceptor on your right and race-track patterns.
The table lists Series 1 to 6 for aeroplanes, with columns for who signals, what you see, the meaning, the response and the meaning of the response.
No common language
If radio contact exists but there is no common language, use the standard phrases, transmitting each phrase twice. For the intercepting aircraft the phrases are: CALL SIGN, "What is your call sign?"; FOLLOW, "Follow me"; DESCEND, "Descend for landing"; YOU LAND, "Land at this aerodrome"; PROCEED, "You may proceed".
For the intercepted aircraft they are: CALL SIGN (call sign), "My call sign is …"; WILCO, "Understood, will comply"; CAN NOT, "Unable to comply"; REPEAT, "Repeat your instruction"; AM LOST, "Position unknown"; MAYDAY, "I am in distress"; HIJACK, "I have been hijacked"; LAND (place name), "I request to land at (place name)"; DESCEND, "I require descent".
The call sign you give is the one used in RTF with ATS units, matching the aircraft identification in the flight plan. Circumstances may not always permit, or make desirable, the use of HIJACK. Note that DESCEND means "descend for landing" from the interceptor, but "I require descent" from the intercepted aircraft.
On the radio side, the intercept control unit and interceptor first try to talk on 121.5 MHz in a common language, using the call signs "INTERCEPT CONTROL", "INTERCEPTOR (call sign)" and "INTERCEPTED AIRCRAFT"; failing that, on other frequencies prescribed by the competent authority or through the ATS unit.
Keep a one-page interception card with the signal series and the phrases in the flight bag, and make sure the aircraft can communicate on 121.5 MHz.
You can print ours: A5 interception card (PDF, 2 sides). It is a learning aid, not an official document.
What ATS does
When an ATS unit learns of an interception in its area, it tries to establish two-way contact, including on 121.5 MHz, tells the pilot about the interception, contacts the intercept control unit and passes information about the aircraft, relays messages, takes all necessary steps for the intercepted aircraft's safety in coordination with the intercept control unit, and informs adjacent FIRs if the aircraft seems to have strayed from them. If the interception is outside its own area, it informs the unit serving the airspace concerned and relays messages as needed.
In the real world
On 8 September 2008 a CTSW microlight that had entered a temporary prohibited zone was intercepted by a Mirage 2000. The microlight's radio was on the club frequency, not 121.5 MHz, so the interceptor's calls were not heard. The occupants did not recognise the interception and took the passes as an invitation to continue. One to two minutes after the jet left, the microlight flew into its wake turbulence; the canopy broke and a door partly opened before the pilot recovered and landed. The BEA found the occupants did not know the interception procedures and recommended that official pilot documentation describe them fully, including the radio frequency, and make them easy to find. Read the BEA report.
Exam traps
"If ATC tells me something different from the interceptor, ATC wins." Ask for clarification but keep following the interceptor, whether through its visual signals or its radio instructions.
"When intercepted, squawk 7500." Select Mode A 7700 unless the ATS unit instructs otherwise.
"A climbing breakaway means follow me." A climbing turn of 90° or more, not crossing your path, means "you may proceed". Follow me is wing rocking and irregular navigation-light flashes, then a slow level turn.
"To say the aerodrome is inadequate, I just raise my gear." Raise the gear (if fitted) and flash the landing lights while passing over the runway between 1 000 and 2 000 ft above aerodrome level, then keep circling.
"Regular and irregular flashing mean the same." Regular on and off of all lights means cannot comply. Irregular flashing means distress.
"Say each phrase once, clearly." Without a common language, transmit each phrase twice. And DESCEND from the intercepted aircraft means "I require descent".
Explain it back
You are flying a light aeroplane and a military jet appears above, ahead and to your left, rocking its wings. Explain in your own words what you do in the first moments, including radio and transponder, and how you would tell the interceptor that you cannot comply and that you are in distress.
Self-check
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You are flying a light aeroplane with a transponder and are intercepted. Which set of actions is correct?mcq · easy
Show answer
The required actions are to follow the interceptor, notify ATS if possible, make a general call on 121.5 MHz and select Mode A 7700 unless ATS instructs otherwise. The first option disobeys the interceptor and uses the wrong code. Climbing away does the opposite of following, and the general call belongs on 121.5 MHz. 7600 is not the code for this and waiting is not an action.
Reference: SERA.11015(b)(1)-(4)
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The intercepting aircraft makes an abrupt climbing turn of 90° or more away from you without crossing your line of flight. What does this mean, and what do you do?mcq · medium
Show answer
An abrupt climbing breakaway of 90° or more, not crossing your path, means you may proceed, and you acknowledge by rocking your wings. Follow me is wing rocking with navigation-light flashes and a slow level turn. Land here is gear down, steady landing lights and a runway overflight. The inadequate-aerodrome signal is one you start, not an interceptor signal.
Reference: SERA.11015, Table S11-1, Series 2
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While you follow an interceptor's visual signals, ATC tells you by radio to turn onto a different heading. What do you do?mcq · medium
Show answer
If radio instructions conflict with the interceptor's visual signals, you ask for immediate clarification while continuing to follow the interceptor's visual instructions. ATC does not outrank the interceptor in this situation. Continuing on your heading ignores the interceptor, and picking the first instruction has no basis in the rule.
Reference: SERA.11015(c)
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You have been told to land at an aerodrome that is unsuitable for your aeroplane and you want to say so with visual signals. What do you do?mcq · hard
Show answer
The signal for 'aerodrome you have designated is inadequate' is gear up (if fitted) and flashing landing lights over the runway in use at more than 300 m (1 000 ft) but not more than 600 m (2 000 ft) above aerodrome level, then circling. Regular on-off of all lights means cannot comply. Rocking wings is the acknowledgement of follow me. Gear down with steady landing lights is the interceptor's 'land here' signal.
Reference: SERA.11015, Table S11-2, Series 4
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You are intercepted, you can talk to the interceptor, but you share no common language, and you cannot comply with its instruction. Which phrase do you use, how many times do you transmit it, and what does the word DESCEND mean when you say it?short · medium
Show answer
Use CAN NOT, meaning 'unable to comply', and transmit each phrase twice. DESCEND from the intercepted aircraft means 'I require descent', while from the interceptor it means 'descend for landing'.
Reference: SERA.11015(e)
Key concepts
Written with ASD-STE100 writing principles: short sentences, one topic per sentence, active voice, one word for one meaning.
First actions when intercepted
An intercepted aircraft must follow the interceptor's instructions at once, and answer its visual signals. Notify the appropriate ATS unit if possible, and try to call on 121.5 MHz with your identity and the nature of the flight. If fitted, select Mode A code 7700, unless ATS instructs otherwise.
Do: if there is no contact on 121.5 MHz, and it is practicable, repeat the call on 243 MHz.
Do: if fitted with ADS-B or ADS-C, select the emergency function, if available, unless ATS instructs otherwise.
Rule: SERA.11015(b)(1)–(5)
Series 1 signal: follow me
The interceptor rocks its wings and flashes its navigation lights, from above, ahead and normally to the left. The meaning is: you have been intercepted, follow me. Respond with wing rocks and irregular flashes of your navigation lights, then follow.
Rule: SERA.11015, Table S11-1, Series 1
Series 2 signal: you may proceed
The interceptor makes an abrupt climbing breakaway of 90° or more, without crossing your line of flight. This series means you can proceed. Respond with a wing rock.
Rule: SERA.11015, Table S11-1, Series 2
Series 3 signal: land here
The interceptor lowers its landing gear, if fitted, shows steady landing lights and overflies the runway in use. This series means land at this aerodrome. Respond the same way and follow the interceptor, and land if landing is considered safe after the overfly.
Rule: SERA.11015, Table S11-1, Series 3
Conflicting instructions
If radio instructions conflict with the interceptor's visual signals, ask for immediate clarification and continue to follow the visual signals. If radio instructions conflict with the interceptor's radio instructions, ask for clarification and follow the interceptor's radio instructions. The interceptor therefore takes priority over other sources, including ATC, while clarification is sought.
Rule: SERA.11015(c), (d)
Your own signals to the interceptor
The intercepted aircraft shows that the aerodrome is inadequate by raising its landing gear, if fitted, and flashing its landing lights over the runway. Regular switching on and off of all lights means cannot comply. Irregular flashing of all lights means in distress.
Rule: SERA.11015, Table S11-2, Series 4, 5, 6
Do: pass over the runway at more than 1 000 ft and not more than 2 000 ft above aerodrome level.
No common language
If there is radio contact but no common language, use the standard phraseology, and transmit each phrase twice. The interceptor uses phrases such as FOLLOW, DESCEND, YOU LAND and PROCEED. The intercepted aircraft uses phrases such as WILCO, CAN NOT, REPEAT, AM LOST and MAYDAY.
Rule: SERA.11015(e); GM1 SERA.11015, 5.2
Avoiding interception
A flight plan must be filed for flights in designated areas or along designated routes, to avoid the possible need for interception. Guidance to States says interception is a last resort, mainly for identification. A 2008 serious incident in France shows the risk: the occupants did not know the procedures, and their radio was not on 121.5 MHz.
Rule: SERA.4001(b)(4)
Do: learn the interception procedures and the emergency frequency before a flight.
Flashcards
Print them: A6 landscape cards (PDF, front and back) · 4 cards per A4 landscape sheet (PDF, cut lines) · Key figures deck (PDF, 9 figures) · A5 interception card (PDF, 2 sides)
Print double-sided, flip on the short edge.
010-05-05-01What do you do first when intercepted?
Follow the interceptor's instructions at once, and answer its visual signals.
010-05-05-02Which frequency do you call first when intercepted?
121.5 MHz, the emergency frequency. If there is no contact and it is practicable, repeat the call on 243 MHz.
010-05-05-03Transponder code when intercepted?
Mode A code 7700, if fitted, unless ATS instructs otherwise.
010-05-05-04How many times is each phrase sent when there is no common language?
Twice.
010-05-05-05Series 1 signal, what does the interceptor mean?
You have been intercepted. Follow me.
010-05-05-06Series 1 signal, how do you respond?
Rock your wings and flash your navigation lights at irregular intervals. Then follow the interceptor.
010-05-05-07Series 2 signal, what does the interceptor mean?
You may proceed. The interceptor makes an abrupt climbing breakaway of 90° or more.
010-05-05-08Series 2 signal, how do you respond?
Rock your wings.
010-05-05-09Series 3 signal, what does the interceptor mean?
Land at this aerodrome. The interceptor lowers its landing gear, if fitted, and overflies the runway in use.
010-05-05-10Series 3 signal, how do you respond?
Respond the same way and follow the interceptor. Land if landing is considered safe after the overfly.
010-05-05-11Radio instructions conflict with the interceptor's visual signals. What do you do?
Ask for immediate clarification and continue to follow the interceptor's visual signals.
010-05-05-12Radio instructions conflict with the interceptor's radio instructions. What do you do?
Ask for clarification and follow the interceptor's radio instructions.
010-05-05-13Whose instructions take priority while clarification is sought?
The interceptor's, over other sources, including ATC.
010-05-05-14Your signal to show that the aerodrome is inadequate?
Raise the landing gear, if fitted, and flash the landing lights over the runway, at more than 1 000 ft and up to 2 000 ft above aerodrome level.
010-05-05-15Your signal to show that you cannot comply?
Switch all available lights on and off regularly, in a way distinct from flashing.
010-05-05-16Your signal to show that you are in distress?
Flash all available lights irregularly.
010-05-05-17The interceptor phrase CALL SIGN means?
What is your call sign?
010-05-05-18The intercepted phrase WILCO means?
Understood, will comply.
010-05-05-19The intercepted phrase CAN NOT means?
Unable to comply.
010-05-05-20The intercepted phrase AM LOST means?
Position unknown.
010-05-05-21The intercepted phrase MAYDAY means?
I am in distress.
010-05-05-22Which flight plan rule helps avoid the need for interception?
A flight plan is required for flights in designated areas or along designated routes.
010-05-05-23Is interception normal practice?
No. It is a last resort, mainly for identification.
010-05-05-24What did the 2008 French microlight incident show?
The occupants did not know the procedures. Their radio was not on 121.5 MHz.
010-05-05-25Aircraft fitted with ADS-B or ADS-C, when intercepted?
Select the emergency function, if available, unless ATS instructs otherwise.
010-05-05-26Closest initial distance of the interceptor in Phase I, for visual identification?
300 m.
010-05-05-27Range within which the interceptor suppresses pressure-altitude reporting?
37 km (20 NM), for interceptors with SSR transponders when the intercepted aircraft has ACAS.
010-05-05-28When intercepted, must you notify ATS?
Notify the appropriate ATS unit, if possible.
Sources
- Commission Implementing Regulation (EU) No 923/2012 (SERA): Article 3; Article 4; SERA.1001; SERA.4001; SERA.11010; SERA.11015; SERA.14095; AMC1 SERA.11015; GM1 SERA.11015 — via EASA Easy Access Rules for Standardised European Rules of the Air (SERA), August 2025, with the related AMC/GM.
- BEA, serious incident to the CTSW microlight 26-ZT, Roussillon, 8 September 2008 (report 26-t080908, May 2011): bea.aero.
This page is educational. It does not replace instruction at your ATO or your aircraft's POH/AFM. Rules change: check the regulation in force.