Emergencies, communication failure and contingencies
Learning objectives
- State the steps of the VFR radio-failure procedure and the transponder code it uses.
- Explain why air traffic control (ATC) can protect other traffic only because the VFR radio-failure procedure is fixed.
- Identify the difference between minimum fuel, urgency (PAN PAN) and distress (MAYDAY), and state what 121.5 MHz is for.
- Explain what air traffic services (ATS) do for an aircraft in an emergency, a strayed or unidentified aircraft, and a lost VFR pilot, and say where ICAO and the EU rule differ.
The idea
Most rules on this page exist so that people who cannot talk can still predict each other. If your radio dies, ATC cannot ask what you plan to do, so the rules tell both sides in advance. You do the known thing, and the controller protects the sky around you on the assumption that you are doing it. If you are in real trouble, the same logic applies: the right words, the right code and the right frequency tell everyone how much help you need and how fast.
Emergency authority and priority
Start with the principle behind everything else. If ATS knows or believes that an aircraft is in an emergency, it gives that aircraft as much consideration, help and priority over other traffic as the situation calls for. The controller's next steps follow your intentions and the traffic picture.
You are the pilot-in-command, and you may depart from the rules of the air when that is absolutely necessary for safety. A controlled flight normally sticks to its flight plan and clearance. If an emergency demands immediate action, you act first. You then tell ATS, as soon as circumstances allow, what you did and that you did it under emergency authority.
Departing from the rules of the air is allowed only when absolutely necessary in the interests of safety. Departing from the flight plan or clearance is allowed only when an emergency needs immediate action, and ATS must then be told as soon as circumstances allow.
Fly the aeroplane first, then navigate, then communicate. Telling ATS early lets them help, but never at the expense of aircraft control. No rule says when to declare an emergency, so declare early: ATS can give priority only once it knows, and a declaration can be downgraded or cancelled later.
Emergency checklists and descent techniques belong in your aircraft's POH/AFM. Check your aircraft's POH/AFM. This page does not replace ATO instruction or the POH/AFM.
Minimum fuel, urgency and distress
Think of a ladder. Each rung tells ATC how much help you need.
Describe this figure
A ladder runs upward from "Normal operation". The first rung, MINIMUM FUEL, is not an emergency: the pilot is committed to one aerodrome, and ATC reports expected delays or none. The next rung, PAN PAN, is urgency: safety is affected but no immediate assistance is needed. The top rung, MAYDAY, is distress: serious or imminent threat needing immediate assistance. Both signals are preferably spoken three times; for fuel distress the pilot says MAYDAY, then FUEL. A bracket beside PAN PAN and MAYDAY points to two tools: squawk 7700 unless ATC has assigned a code, and 121.5 MHz for genuine emergencies only.
The figure shows four rungs from bottom to top: normal flight, MINIMUM FUEL, PAN PAN and MAYDAY. Beside the upper rungs sit two tools, the transponder code 7700 and the frequency 121.5 MHz. The word MINIMUM FUEL is marked as "not an emergency".
MINIMUM FUEL. This tells ATC that you are now committed to one specific aerodrome. Any change to your clearance could mean landing with less than the planned final reserve. It is not an emergency, but an emergency is possible if there is more delay. When you report it, the controller tells you as soon as practicable about expected delays, or that none are expected.
Urgency. This is a condition affecting the safety of an aircraft or vehicle, or of a person on board or in sight, that does not need immediate assistance. The first urgency message starts with PAN PAN, preferably spoken three times. PAN is pronounced like the French word "panne".
Distress. This is a condition of serious and/or imminent threat that needs immediate assistance. The first distress message starts with MAYDAY, preferably spoken three times. If your fuel state makes distress necessary, you say MAYDAY, preferably three times, followed by the nature of the distress, FUEL.
The message goes out on the air-ground frequency you are already using, and the traffic normally stays there unless moving gives better help. Distress traffic has absolute priority. Stations that hear it do not transmit on that frequency unless the distress is over or has moved, the controlling ATS unit allows it, or they must help. Urgency traffic comes next, ahead of everything except distress.
The unit that acknowledges your distress message takes control of the communications, or clearly hands that over, and makes sure the information reaches the other ATS units and your operator. When you are no longer in distress, you send a message cancelling the condition. Only the ATS unit controlling the traffic ends distress traffic and silence.
For the transponder side, select 7700 to show an emergency, unless ATC has already assigned a code. Even then you may select 7700 if you have a specific reason to think it is the best action. The full code story is on page 010-06-02.
"MINIMUM FUEL is an emergency call." No. It is not an emergency. It warns that one could follow with more delay. The fuel emergency itself is MAYDAY followed by FUEL.
What ATS does for you
Once ATS has established that you are in an emergency, nearby aircraft are told its nature as soon as practicable. ATS uses every communication facility to keep contact with you. It plots your flight to work out your probable position and maximum range, and follows you on the display where surveillance exists. On a controlled aerodrome, emergency vehicles going to help have priority over all other surface traffic.
If horizontal separation cannot be kept, ATC may use emergency separation of half the normal vertical minimum: 500 ft where 1 000 ft normally applies, or 1 000 ft where 2 000 ft applies. The crews are told that it is in use and get essential traffic information.
ICAO adds that the controller first tries to learn identity, type of emergency, intentions, position and level, then offers suitable aerodromes, minimum safe altitudes and weather.
The emergency frequency 121.5 MHz
When normal channels fail you, a common, well-known frequency is needed: 121.5 MHz.
Describe this figure
A banner states that 121.500 MHz is for genuine emergencies only. Six icon cards show the listed uses: a clear channel when normal channels are busy; an aircraft to aerodrome channel not normally used by international services; a common search and rescue channel; contact when own equipment failure prevents use of normal channels; ELTs and survival craft; and interception. Below, one panel says ATS stations keep a continuous watch during service hours, and another says aircraft guard it on long over-water flights, where an ELT is required and where the authority requires it. A note says other uses are exceptional and search and rescue coordination must not hinder distress traffic.
The figure shows six small icons, one for each listed use, and below them two groups showing who listens: ATS stations and aircraft.
121.5 MHz is for genuine emergencies only. The listed uses are: a clear channel when normal channels are busy; a channel between aircraft and aerodromes not normally used by international services when an emergency arises; a common channel for search and rescue; contact when equipment failure prevents use of normal channels; emergency locator transmitters (ELTs) and survival craft; and interception. A Member State may exceptionally allow other uses, such as training, limited to what is necessary and with low impact on aircraft in distress.
Who listens? ATS providers make the frequency available at all area control centres and flight information centres, and at towers and approach units serving international aerodromes. Aeronautical stations keep a continuous listening watch during their hours of service. Aircraft must guard it on long over-water flights and over areas where an ELT is required, except while the radio is busy on another channel or when equipment or workload does not allow it. They must also guard it where the competent authority requires it because of interception or other hazards. Other flights should guard it as far as possible.
"Every ATS unit listens on 121.5 MHz around the clock." No. Stations listen during their hours of service, and not every aeronautical station guards it continuously. Also, your emergency message goes first on the frequency in use. 121.5 MHz is an extra option, not a requirement.
Radio communication failure
You call, and nobody answers. Before you decide it is a failure, check the simple causes: volume and squelch, the selected frequency, headset plugs, the avionics master and a stuck transmit switch. A stuck switch blocks the frequency for everyone.
Describe this figure
The flowchart starts with "No reply from ATS". Step 1 is good practice: check volume and squelch, frequency, headset plugs, avionics master and a stuck transmit switch. Steps 2 and 3 try the previous channel, another suitable channel, then ATS units, other aircraft and mobile phones. Step 4 sends the message twice, preceded by TRANSMITTING BLIND; a side box covers receiver-only failure. Step 5 watches for light signals in controlled aerodrome traffic, step 6 sets 7600, and step 7 stays in VMC, lands at the nearest suitable aerodrome and reports arrival.
The flowchart runs top to bottom: no reply, simple checks, previous channel, another channel or station, two blind transmissions, "watch light signals" if in aerodrome traffic, code 7600, ending with "stay in VMC, nearest suitable aerodrome, land, report arrival".
A controlled flight keeps a continuous listening watch on the ATC channel and makes two-way contact as needed. If a failure prevents this, the communication-failure procedures apply. The sequence is this.
- Try to get through. Try the previous channel, then another channel suitable for the route. Then try the appropriate ATS unit, other ATS units or other aircraft by every available means, including data link, satellite voice and mobile phones. Once through, say that contact on the assigned channel could not be made.
- Transmit blind. If all that fails, transmit your message twice on the designated channels, preceded by TRANSMITTING BLIND, with the addressee if necessary.
- Apply the failure procedure. If you are in the aerodrome traffic at a controlled aerodrome, watch for visual light signals. Set Mode A code 7600 and/or the ADS-B loss-of-communication indication. The light signals are taught on page 010-05-04.
- Fly the VFR procedure. Continue in VMC, land at the nearest suitable aerodrome and report your arrival to the appropriate ATS unit by the quickest means.
To judge suitability, consider runway characteristics, facilities and how complex the operating environment is.
If only your receiver has failed, send your reports at the scheduled times or positions on the channel in use, preceded by TRANSMITTING BLIND DUE TO RECEIVER FAILURE. Give the message, then a complete repetition, state the time of your next transmission and give your intentions for the rest of the flight.
A VFR flight with radio failure continues in VMC, lands at the nearest suitable aerodrome and reports arrival by the quickest means.
Why the procedure is fixed
Describe this figure
The left column lists the pilot's actions: restore contact and transmit blind, squawk 7600, watch for light signals at a controlled aerodrome, stay in VMC and land, then report arrival. The right column shows ATS assuming the pilot follows the rule and protecting other traffic on that basis. ATS calls the aircraft, may ask for IDENT, a manoeuvre or a code change, asks others to relay, and sends only non-clearance messages blind. It tells units along the route and nearby aircraft. After 30 minutes without a report or landing it tells operators and pilots concerned; this does not replace alerting. A banner says quick arrival reports close the loop.
The figure is split into two panels. The left panel, "Pilot", lists: stay in VMC, land nearest suitable, report arrival. The right panel, "ATS", lists: call, test the receiver, relay, inform units, protect other traffic.
ATC bases its service to other traffic on the premise that you follow the failure procedure. For a VFR flight, ATC assumes you will stay in VMC, land at the nearest suitable aerodrome and report arrival, and it protects other traffic on that basis. That is why a "creative" plan, such as flying on to your planned destination, is so dangerous: ATC is not expecting it. Reporting your arrival quickly closes the loop and avoids needless alerting and search action.
What does ATC do meanwhile? If an expected call does not come, it calls you on the frequencies you may be listening to. It may ask you to acknowledge by a manoeuvre, IDENT or a code change, then asks other units and aircraft on the route to relay, and starts telling your operator. ATC does not transmit clearances blind, except when the originator specifically asks. Other messages go blind on the frequencies you may be listening to. ATC forwards news of an apparent failure to all ATS units along the route, and again when you regain contact or land.
If the arrival unit suspended normal operations for you and you have not reported or landed within 30 minutes after the latest of your ETA, the area control centre's ETA or the last acknowledged EAT, ATC tells the operators and pilots concerned, and normal control resumes if they wish. This does not replace the alerting service, which is taught on page 010-07-04.
IFR as a contrast only
Radio failure for an IFR flight is a different procedure, and you should know the contrast. An IFR flight keeps its last assigned speed and level (or the minimum flight altitude if higher) for 20 minutes, then follows the filed plan to the destination aid. An IFR flight that meets VMC and decides to continue in VMC sets code 7601, lands at the nearest suitable aerodrome and reports arrival. Code 7601 is a recent EU addition, applying since 1 May 2025, and ICAO has no such code. ICAO says 7 minutes instead of 20 in airspace where surveillance is used. The EU rule in force says 20 minutes.
"7601 is the VFR radio-failure code." It is not. VFR uses 7600. 7601 is for an IFR flight that meets VMC and continues in VMC.
Contingencies on the ground side
ATS providers plan for their own failures: every provider has contingency plans for events that seriously degrade or interrupt its services, drawn up in coordination with adjacent providers.
For radio, the causes include ground radio failure, airborne equipment failure, a frequency blocked by accident, or unauthorised use. If the ground radio fails completely, the controller tries 121.5 MHz. The controller also tells adjacent units and may have controlled flights hold or re-route outside the affected area. If an aircraft transmitter blocks the frequency, ATC tries to identify the aircraft and reach it by other means to have the crew stop transmitting. If false or deceptive transmissions occur, ATC corrects them and warns all aircraft to verify instructions and clearances before acting. ICAO adds that crews challenge or verify any instruction or clearance they suspect may be false.
If a system failure leaves you below the performance needed for the airspace you are in, tell ATC without delay.
Other emergency situations
Collision-avoidance advice. Some larger aircraft carry a collision-avoidance system (ACAS II). If it gives a resolution advisory (RA), the pilot follows it at once, even against an ATC instruction, unless that would endanger the aircraft. The pilot never manoeuvres opposite to the RA and tells ATC as soon as workload permits. After an RA is reported, the controller does not try to change that aircraft's flight path until the pilot reports CLEAR OF CONFLICT.
Emergency descent. In a typical unpressurised aeroplane, you are most likely to meet this as a listener. If you hear an emergency-descent broadcast, the guidance is to continue on your clearance and keep listening, unless ATS tells you to clear the area or there is immediate danger. Look out for traffic. If you must descend quickly yourself, the guidance says not to go below the lowest published minimum altitude giving 1 000 ft of obstacle clearance, or 2 000 ft in designated mountainous terrain.
Unlawful interference. An aircraft under unlawful interference tries to set code 7500 and to tell ATS about significant circumstances and any deviation from the flight plan. 7700 may be used if circumstances warrant. The pilot-in-command tries to land as soon as practicable at the nearest suitable aerodrome, unless the situation on board dictates otherwise. ATS answers requests promptly and speeds up the flight, especially the landing. ATS makes no reference on the radio to the nature of the emergency unless the aircraft has mentioned it first and ATS is sure that doing so will not make things worse.
Strayed and unidentified aircraft
A strayed aircraft has deviated significantly from its intended track, or reports it is lost. An unidentified aircraft is one seen or reported in an area whose identity has not been established.
| Topic | Strayed aircraft | Unidentified aircraft |
|---|---|---|
| Definition | Has deviated significantly from its intended track, or reports that it is lost. | Seen or reported operating in an area, but its identity has not been established. |
| What ATS does | If the position is unknown: tries to make two-way contact and uses all means to fix the position. Once the position is known: tells the aircraft where it is and what corrective action to take. | Tries to identify it when needed for ATS or by the military: calls it, asks other ATS units in the FIR and adjacent FIRs to help, asks other aircraft in the area. |
| Who else is told | ATS units into whose area it may stray, and the military as locally agreed. These units and other aircraft are asked to help find and contact it. Details of the position go to other ATS and military units as needed. | The military unit, once the identity is known. |
| Link to interception | Corrective action is given immediately if interception or another hazard is possible. Navigation help matters most when the aircraft is straying, or about to stray, into an area where it risks interception or another hazard. ATS considers that it may be under unlawful interference and, if it thinks so, tells the designated authority at once. | ATS considers that it may be under unlawful interference and, if it thinks so, tells the designated authority at once. |
| Both at once | The same aircraft may be "strayed" to one unit and "unidentified" to another. | |
Describe this figure
The table has one column for strayed aircraft and one for unidentified aircraft. A strayed aircraft has deviated significantly from track or reports it is lost; an unidentified aircraft is seen or reported but its identity is not established. For a strayed aircraft ATS seeks contact, fixes the position and gives corrective action. For an unidentified aircraft ATS calls it and asks other units and aircraft to help identify it. ATS units, the military and other aircraft are involved. For both, ATS considers possible unlawful interference and tells the designated authority at once if it thinks so.
The table has two columns, strayed and unidentified, with rows for definition, what ATS does, who else is told, and the link to interception.
If a strayed aircraft's position is unknown, ATS tries two-way contact and uses all means to fix its position. It informs ATS units into whose area it may stray and the military as locally agreed, and asks them and other aircraft to help. Once the position is known, ATS tells you where you are and what corrective action to take, immediately if interception or another hazard is possible. For an unidentified aircraft, ATS calls it, asks other ATS units in the area and adjacent areas to help, and asks other aircraft in the area. It tells the military unit once the identity is known. With either, ATS considers that the aircraft may be under unlawful interference and, if it thinks so, tells the designated authority at once. Interception itself is taught on page 010-05-05.
If you are unsure of your position, call the ATS unit in use, or 121.5 MHz if you have no other contact, early, while you still have fuel, daylight and height.
Lost or caught by weather: ICAO assistance
The EU text is silent on assisting a lost VFR pilot, so this section teaches what ICAO says, not an EU rule.
ICAO says a VFR flight that reports being uncertain of its position or lost, or that runs into adverse weather, should be treated as an emergency. The controller stays clear, concise and calm and does not question your faults at that stage.
Describe this figure
A banner says surveillance-based help is given only at the pilot's request or with agreement, aiming to return the aircraft to VMC without entering cloud. An aeroplane approaches a cloud, labelled lost or caught by weather. Four boxes show what ATS can do: fix the position by surveillance, direction-finder, navigation aids or another aircraft; give nearby aerodromes in VMC; give the minimum flight altitude; suggest a track, heading or climb. A further box covers a clear frequency and gentle manoeuvres. A checklist lists ten items the pilot should have ready, from flight conditions to endurance.
The figure shows a VFR aircraft near a cloud edge with four help options around it, and a checklist of information to have ready beside it.
Depending on the case, the controller may ask for: flight conditions, position and level, speed and heading since the last known position, experience, navigation equipment, SSR code, ADS-B capability, departure and destination, persons on board and endurance.
ICAO says the help can include a position fix from a surveillance system, a direction-finder, navigation aids or another aircraft sighting you, taking care that you do not enter cloud. You also get information on nearby suitable aerodromes in VMC. If you report difficulty staying in VMC, the controller gives the minimum flight altitude for the area. If your position is reasonably certain and you are below that altitude, the controller may suggest a track, heading or climb to reach a safe level.
ICAO says surveillance-based assistance to a VFR flight is given only at your request or with your agreement, and the type of service is agreed with you. In bad weather the main aim is to get you back into VMC as soon as possible without entering cloud. If you cannot avoid IMC, turns and speed reductions are done clear of cloud if possible, and abrupt manoeuvres are avoided.
In the real world
On 11 February 2022 a private flight in Sussex lost engine power when one selected tank ran dry, although enough fuel remained in other tanks. The pilot made a MAYDAY on the local aerodrome frequency. A nearby air ambulance crew heard it and went to the site of the forced landing. The lesson: a MAYDAY on the frequency in use brings help from anyone listening, not only from ATS.
On 1 March 2011, poor VHF reception meant the pilot could not reach the approach unit he had planned to call. He returned to the departure aerodrome, where communications with the tower stayed poor, and the landing ended in a nose-over. The pilot said the radio problems had distracted him, and a faulty coaxial connection was found afterwards. The lesson: a degraded radio is a workload problem, so fly the aeroplane first.
Exam traps
"After landing, the job is done." Not yet. Report arrival by the quickest means, otherwise alerting action may start.
"With radio failure a VFR flight continues to its planned destination." It lands at the nearest suitable aerodrome. Routing by the flight plan is the IFR procedure.
"Squawk 7600 first, then think." The sequence is to try to re-establish contact by all means first, then apply the failure procedure, including 7600.
"ATC will send me a new clearance blind." Clearances are not transmitted blind, except at the specific request of the originator. Only other messages go blind.
"IFR radio failure under surveillance: hold level for 7 minutes." That is the ICAO assumption. The EU rule in force is 20 minutes, and neither applies to VFR.
Explain it back
Your radio goes silent in VFR flight, ten minutes from your destination, and a controller can only guess what you will do. Walk through what you do, in order, and explain why the controller can protect other traffic without hearing from you.
Self-check
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CS-ABC, a VFR flight in good weather, loses all radio contact. Calls on the previous and another suitable channel, and two blind transmissions, bring no answer. Which action completes the correct procedure?mcq · easy
Show answer
After the attempts to re-establish contact fail, the failure procedure applies: code 7600, stay in VMC, land at the nearest suitable aerodrome and report arrival quickly. The first option is the IFR procedure. The second uses 7601, which is only for an IFR flight that continues in VMC, and goes to the planned destination instead of the nearest suitable aerodrome. The fourth declares a distress that was not described.
Reference: SERA.14083(a); SERA.14083(c)(2); SERA.14083(c)(3)
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Why does ATC treat a VFR aircraft with radio failure the way it does?mcq · medium
Show answer
The procedure is fixed so that both sides can predict each other: ATC protects other traffic assuming the pilot does exactly the known procedure. Clearances are not sent blind unless the originator specifically asks. Following the filed plan is the IFR logic, not the VFR one. Nothing requires a switch to 121.5 MHz.
Reference: SERA.14083(d); AMC1 SERA.14083(d); SERA.14083(b)(3)
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You are flying CS-ABC to a single aerodrome. Delay for a runway inspection would mean landing below your planned final reserve, but you are not yet in difficulty. What do you tell ATC?mcq · medium
Show answer
MINIMUM FUEL tells ATC you are committed to one aerodrome and that further delay could eat into the final reserve. It is not an emergency, and ATC then tells you about expected delays. MAYDAY with FUEL is for when the fuel state makes distress necessary, which has not happened. PAN PAN with 7700 declares an urgency that is not described here. Saying nothing denies ATC the chance to help.
Reference: SERA.11012(a); SERA.11012(b); GM1 SERA.11012
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Which statement about 121.5 MHz is correct?mcq · medium
Show answer
The frequency is for genuine emergencies, with exceptional limited other uses possible, and a distress message goes first on the frequency already in use. It is not mandatory for all messages. Stations keep watch during their hours of service, not around the clock. Routine reports are not among its uses.
Reference: SERA Article 4a; SERA.14095(d); SERA.14080(b)
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A VFR pilot reports being lost and close to cloud. Which statement matches what ICAO provides, and its status?mcq · hard
Show answer
Under ICAO, a lost VFR flight or one in adverse weather should be treated as an emergency, with no questioning of faults, and surveillance help depends on the pilot's request or agreement. The aim is to get back to VMC without entering cloud, so the third option is wrong. The first option attributes this to the EU rule, which has no equivalent. No MAYDAY is required before help, so the fourth option is wrong.
Reference: ICAO Doc 4444 15.4.1.1; ICAO Doc 4444 15.4.1.6; ICAO Doc 4444 15.4.1.7
Key concepts
Written with ASD-STE100 writing principles: short sentences, one topic per sentence, active voice, one word for one meaning.
VFR radio failure procedure
A VFR flight with radio failure stays in visual meteorological conditions (VMC). It lands at the nearest suitable aerodrome and reports its arrival by the quickest means.
Rule: SERA.14083(c)(3)
Do not: Do not enter instrument meteorological conditions (IMC) after a radio failure.
Radio communication failure procedure
Before this procedure, the crew tries the previous channel and then another suitable channel. If both fail, it tries other ATS units or other aircraft by every available means.
If these attempts still fail, the aircraft sets Mode A code 7600. At a controlled aerodrome, it also watches for light signals when it is in the aerodrome traffic.
Rule: SERA.14083(a), (c)(2)
Predictable procedure protects other traffic
ATC gives other traffic its service on the premise that the aircraft follows the radio failure procedure. Controllers plan around that premise, so the pilot follows the procedure exactly.
Rule: SERA.14083(d)
Emergency authority
The pilot-in-command can depart from the rules of the air when this is absolutely necessary for safety. A controlled flight can also depart from its flight plan or clearance when an emergency demands immediate action. ATS gives an aircraft in an emergency as much help and priority as the situation calls for. The pilot must tell ATS, as soon as circumstances allow, what was done and that emergency authority was used.
Rule: SERA.8020(a)
Distress and urgency
Distress is a condition of serious and/or imminent threat that needs immediate assistance. Urgency is a condition affecting the safety of an aircraft or vehicle, or of a person on board or in sight. That condition does not need immediate assistance. The first distress message starts with MAYDAY, and the first urgency message starts with PAN PAN. Each signal is preferably spoken three times. Distress traffic has absolute priority, and urgency traffic comes next.
Rule: SERA.14095(a)(1), (a)(2)
Emergency frequency 121.5 MHz
The emergency frequency 121.5 MHz serves genuine emergencies only. Aeronautical stations keep a continuous watch on it during their hours of service. Aircraft must guard it on long over-water flights and over areas where an emergency locator transmitter (ELT) is required. This duty stops while the radio is busy on another channel. Aircraft must also guard it where the competent authority requires it.
Rule: SERA.14080(a)(1), (a)(2)
Unlawful interference
An aircraft under unlawful interference tries to set code 7500 on its transponder. Code 7700 can be used instead when circumstances warrant. The pilot tries to tell ATS about significant circumstances and any departure from the flight plan. ATS does not mention the nature of the emergency on the radio first. ATS speaks about it only when the aircraft mentions it first and ATS is sure this will not make things worse.
Rule: SERA.11005(aa), SERA.13005(a)(3)
Strayed aircraft
A strayed aircraft has left its intended track significantly, or it reports that it is lost. Once ATS knows the position, it tells the aircraft where it is and what corrective action to take. ATS gives this at once when interception or another hazard is possible.
ICAO Doc 4444 recommends that ATS handles a lost VFR pilot as an emergency, without blame at that stage. The EU rules in SERA do not state this.
Rule: SERA.11010(a)(3)
Flashcards
Print them: A6 landscape cards (PDF, front and back) · 4 cards per A4 landscape sheet (PDF, cut lines) · Key figures deck (PDF, 17 figures)
Print double-sided, flip on the short edge.
010-07-06-01VFR flight with radio failure: which weather does it stay in?
Visual meteorological conditions (VMC).
010-07-06-02VFR flight with radio failure: where does it land?
At the nearest suitable aerodrome.
010-07-06-03VFR flight with radio failure: how does it report its arrival?
To the appropriate ATS unit, by the quickest means.
010-07-06-04Radio failure: which channel does the crew try first?
The previous channel, then another channel suitable for the route.
010-07-06-05Radio failure: whom does the crew try to reach after the channel attempts fail?
The appropriate ATS unit, other ATS units or other aircraft, by every available means.
010-07-06-06Radio communication failure: which transponder code does the aircraft set?
Code 7600, after the attempts to re-establish contact fail.
010-07-06-07Radio failure at a controlled aerodrome: what does the aircraft watch for?
Visual (light) signals, when it is in the aerodrome traffic.
010-07-06-08Why is the radio failure procedure fixed?
ATC gives other traffic its service on the premise that the aircraft follows the procedure.
010-07-06-09Which transponder code shows an emergency?
Code 7700, unless ATC has assigned a code. Even then, a pilot can select 7700 for a specific reason.
010-07-06-10Which transponder code shows unlawful interference?
Code 7500. Code 7700 can be used instead when circumstances warrant.
010-07-06-11IFR flight with radio failure that continues in VMC: which Mode A code?
Code 7601. ICAO has no code 7601.
010-07-06-12What is the VHF emergency frequency?
121.500 MHz (121.5 MHz), for genuine emergencies only.
010-07-06-13Which aircraft must guard 121.5 MHz?
Aircraft on long over-water flights and over areas where an ELT is required, except while the radio is busy on another channel or equipment or workload does not allow it. Also where the competent authority requires it.
010-07-06-14Distress message: which opening word, and how often is it spoken?
MAYDAY, preferably three times.
010-07-06-15Urgency message: which opening word, and how often is it spoken?
PAN PAN, preferably three times.
010-07-06-16What is a distress condition?
A serious and/or imminent threat that needs immediate assistance.
010-07-06-17Distress or urgency: which traffic has absolute priority?
Distress traffic. Urgency traffic comes next.
010-07-06-18Blind transmission with no contact by any means: how is the message sent?
Twice, preceded by TRANSMITTING BLIND.
010-07-06-19Receiver failure: what is the preamble of a blind transmission?
TRANSMITTING BLIND DUE TO RECEIVER FAILURE, then the message and one complete repetition.
010-07-06-20IFR radio failure: for how long does the aircraft keep its last assigned speed and level?
20 min, or the minimum flight altitude if higher. Counted from a missed required report or from squawking 7600 under surveillance.
010-07-06-21IFR radio failure: land within how long after the ETA or the last acknowledged EAT?
Within 30 min after whichever is later: the ETA or the last acknowledged EAT.
010-07-06-22Arrival unit suspended normal operations: after how long without a report does ATC inform operators?
30 min after the latest of the pilot ETA, the ACC ETA or the last acknowledged EAT.
010-07-06-23ICAO only: how long does an IFR aircraft keep its last speed and level in surveillance airspace?
7 min under ICAO. SERA uses 20 min, and the EU rule in force is 20 min.
010-07-06-24Emergency descent guidance over normal terrain: what clearance above obstacles?
1 000 ft above the highest obstacle in the area. Do not go below the lowest published minimum altitude giving this clearance.
010-07-06-25Emergency descent guidance in designated mountainous terrain: what clearance above obstacles?
2 000 ft above all obstacles in the area.
010-07-06-26Emergency separation where the 1 000 ft minimum applies: vertical separation?
500 ft, half the vertical minimum, when horizontal separation cannot be kept.
010-07-06-27Emergency separation where the 2 000 ft minimum applies: vertical separation?
1 000 ft, half the vertical minimum, when horizontal separation cannot be kept.
010-07-06-28Emergency in the air: what does ATS give the aircraft?
As much consideration, help and priority over other traffic as the situation calls for.
010-07-06-29Emergency authority: when can the pilot-in-command depart from the rules of the air?
When this is absolutely necessary for safety. The pilot then tells ATS afterwards.
010-07-06-30Unlawful interference: what does the pilot tell ATS?
Significant circumstances, and any departure from the flight plan.
010-07-06-31Unlawful interference: does ATS mention the nature of the emergency on the radio first?
No. It does so only when the aircraft mentions it first and ATS is sure this will not make things worse.
010-07-06-32What is a strayed aircraft?
An aircraft significantly off its intended track, or one that reports it is lost.
010-07-06-33Strayed aircraft: what does ATS give once it knows the position?
Where the aircraft is and the corrective action to take, given at once if interception or another hazard is possible.
010-07-06-34ICAO only: how is a lost VFR pilot handled?
As an emergency, without blame at that stage. The EU rules in SERA do not state this.
Sources
- Commission Implementing Regulation (EU) No 923/2012 (SERA) — via EASA Easy Access Rules for Standardised European Rules of the Air (SERA), August 2025, with the related AMC/GM.
- Commission Implementing Regulation (EU) 2017/373 (ATM/ANS), Annex I definitions and Annex IV (Part-ATS) — via EASA Easy Access Rules for ATM/ANS – Provision of Services, March 2025, with the related AMC/GM.
- ICAO Annex 11, Air Traffic Services, 15th edition (2018), and ICAO Doc 4444, PANS-ATM, 16th edition (2016): used for ICAO comparisons only.
- Commission Implementing Regulation (EU) 2024/404 amending SERA, Article 2 (application).
- AAIB (UK) report AAIB-28013, Piper PA-32-300 G-KNOW, 11 February 2022: gov.uk.
- AAIB (UK) Bulletin 6/2011, EW/G2011/03/02, Spitfire Mk 26 replica G-CCGH, 1 March 2011: gov.uk.
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.