What does squawk 7700 mean? The emergency codes 7700, 7600 and 7500

Every airliner's transponder sends a four-digit code to air traffic control, the squawk. Almost always it is just a label that controllers assign to tell aircraft apart. Three codes are different: they mean trouble, they mean the same thing in every country, and every flight tracker shows them.

The three emergency codes

ICAO, which sets the world's aviation standards, reserves these three codes everywhere. Most other codes are assigned by controllers flight by flight, and some mean different things in different countries: see the squawk codes list.

7700: general emergency

A crew facing an emergency sets 7700 to make sure controllers notice. In the FAA's words, the code normally triggers an alarm or a special indicator at every control position that sees the aircraft; on US controllers' screens its label reads EMRG. The UK's radiotelephony manual says it gives the emergency controller both a sound and a visual warning, and advises crews to set it before they make the emergency call.

What counts as an emergency is broad. Pilots declare either distress, "Mayday", when the aircraft is in serious and imminent danger and needs help at once, or urgency, "Pan-Pan", for a serious problem that does not need immediate help. The FAA says an aircraft is in at least an urgency condition as soon as its pilot is in doubt about its position, its fuel or the weather. A passenger who falls seriously ill, a technical fault, smoke in the cabin or a pressurisation problem are all reasons a crew may set 7700.

Not every emergency shows 7700, though. The rules differ in the detail but agree on the principle:

• In Europe and the UK, a crew already given a code by air traffic control may keep it, at the pilot's or controller's discretion, and select 7700 when there is a reason to.
• In the US, a crew already in radio contact keeps its code unless told otherwise, and uses 7700 when it cannot make contact at once.

And in the US, controllers who have identified an aircraft and are talking to it may ask the crew to change from 7700 back to an ordinary code, so that other controllers can see the emergency is being handled. That is why a flight can show 7700 on a tracker for a few minutes and then not at all, while the emergency goes on.

Modern transponders and ADS-B also send an emergency status alongside the code, so the alert reaches both radar and the receivers that flight trackers use.

7600: radio failure

7600 means the crew has lost two-way radio contact with air traffic control. It is used whether the radios have failed or the crew simply cannot reach anyone on the frequency. Controllers then know the aircraft will follow the published procedures for a radio failure and keep other traffic clear of it.

In FlyScout's records, 7600 is the second most common of the three: 31 aircraft in the 29 days to 16 October 2026, against 120 squawking 7700.

7500: unlawful interference

7500 is the code for unlawful interference with the flight. The FAA describes it as the aircraft being hijacked or forced to a new destination. European rules say a crew should attempt to set it, or use 7700 if the circumstances call for it.

Controllers never assign 7500 themselves unless the crew has reported a hijack first, and they ask the crew to confirm it. To keep false alarms away, pilots changing codes are told never to pass through 7500, 7600 or 7700 on the way: from 2700 to 7200, for example, they go through 2200. FlyScout recorded 4 aircraft showing 7500 between 18 September and 16 October 2026; it records the code the transponder sent, not what was happening on board.

How often aircraft squawk 7700

Flightradar24 looked at its own data from late December 2022 to mid-March 2024: on average 36 flights a week squawked 7700, never fewer than 19 and at most 67 in a week, and the busiest single day had 18. Against the 10 to 17 million flights it tracks a week, that is a tiny share.

FlyScout's own count, from 18 September to 16 October 2026, was 155 aircraft with an emergency code: 120 squawking 7700, 31 squawking 7600 and 4 squawking 7500. 71 were over Europe and 72 over North America, where the receiver networks are densest. Of the 155, at least 12 landed at an airport other than their destination, and 9 more returned to the airport they had left.

What a 7700 does and does not tell you

A squawk says that something needs attention, not what. Flightradar24 puts it plainly: 7700 means a problem that needs immediate attention, not necessarily immediate danger. Most end in an ordinary landing, sometimes at another airport, and some serious incidents never show 7700 at all.

FlyScout treats it the same way. It finds aircraft squawking 7700, 7600 or 7500 anywhere in the world, follows them to the landing, and says where they came down and whether that was where they were going. It never guesses at the cause: the track shows where an aircraft went, and only the crew, the airline or the investigators can say why. To follow emergencies live, see how to track emergency flights.