What does squawk 7700 mean?
Squawk 7700 means the aircraft has declared an emergency. The crew has set the code on its transponder so every controller can see at a glance that it needs priority. Most 7700 flights end in a normal landing at the nearest suitable airport.
What a squawk code is
Every airliner, and most other aircraft, carries a transponder: a box that answers radar and broadcasts the aircraft’s details. One of those details is a four-digit code the crew dials in, called the squawk. Each digit runs from 0 to 7, which gives 4,096 possible codes. Controllers hand out most of them one flight at a time, so a code on the radar screen points to one aircraft. A few codes are reserved, and everyone in aviation knows them by heart.
7700: general emergency
7700 is the all-purpose emergency code. A crew sets it when something serious is happening and they need help: an engine problem, smoke in the cabin, a pressurization issue, a sick passenger who has to get to a hospital. The code makes the aircraft stand out on every radar screen that can see it, not just the one controller the crew is talking to.
7600: radio failure
7600 means the crew can’t talk to air traffic control. The aircraft may be perfectly healthy, with a broken radio or a lost frequency. The crew follows a published procedure for flying and landing without radio, and controllers clear other traffic out of the way because they know what the aircraft will do next. Many are sorted out quickly, often when the crew finds a frequency that works.
7500: unlawful interference
7500 is the hijack code. It is taken very seriously: controllers ask the crew to confirm it, and the response can involve security services and military aircraft. It is also the code most likely to be a mistake. Crews occasionally dial 7500 by accident, usually while meaning to set a different code, and it gets cleared up quickly once the controller asks. A 7500 on a flight map is worth noticing, but it is not a reason to assume the worst.
The everyday codes
- 1200: the standard code in the United States for a pilot flying by visual rules who isn’t using air traffic control. A Cessna on a weekend flight is usually squawking 1200.
- 7000: the equivalent visual-flight code in much of Europe.
- 2000: a general code used where no specific code has been assigned, for example when an aircraft arrives in radar coverage from somewhere without it, or over the ocean.
Anything else is usually a code a controller assigned to that one flight.
What happens after a 7700
The aircraft gets priority. Controllers clear a path, give it the most direct route and the runway it wants, and have fire and rescue crews waiting at the airport. That is routine for them and doesn’t mean anything is on fire. Many emergencies are precautionary: the crew lands at the nearest suitable airport because a warning came on, not because the aircraft is in danger. A heavy jet that has just taken off may circle for a while first to burn fuel and get down to a safe landing weight. More on why planes circle.
Once the crew is talking to a controller, they are sometimes asked to switch back to a normal code. So a 7700 can disappear from a flight map while the emergency carries on.
You can see squawks on a flight map
The squawk code is part of what the transponder broadcasts, so live aircraft maps can show it. That is how 7700 flights end up being watched by thousands of people at once. How those broadcasts work. In Bogey, any aircraft squawking 7700, 7600 or 7500 wears a red halo on the map, so an emergency near you is impossible to miss. Tap it to see the type, the operator and where it’s headed, which usually tells you where it will land.
