Squawk code · emergency

Squawk 7700: General emergency

Squawk 7700 is the universal transponder code a pilot sets to declare a general emergency.

Squawk 7700 means "this aircraft has an emergency." It is the one code every transponder-equipped aircraft in the world uses to declare a general emergency, and it instantly flags the flight on every air traffic control screen that can see it. Most 7700 flights end with a normal landing.

What 7700 means

A transponder replies to radar and broadcasts a four-digit octal code (each digit 0 to 7) called a squawk. Controllers normally assign a unique code to each flight. Code 7700 is reserved worldwide, by ICAO convention and by the FAA's Aeronautical Information Manual (AIM 6-2-2), for an aircraft in an emergency condition. When a pilot selects it, radar displays highlight the target, sound an alert and show "EMRG" next to the data block.

"Emergency" covers a wide range of situations. Common reasons include:

• A medical problem with a passenger or crew member that needs a fast, priority landing.
• An engine failure or shutdown, including precautionary shutdowns on twin-engine jets.
• Smoke, fumes or an unexplained smell in the cabin.
• Pressurization trouble, which usually means a controlled descent to about 10,000 ft.
• Hydraulic, flap, landing gear or flight control indications.
• Low fuel declared as an emergency ("mayday fuel").

What pilots and controllers do

The first rule in the cockpit is aviate, navigate, communicate. If the crew is already talking to a controller, they often declare the emergency by radio ("mayday" or "declaring an emergency") and the controller may ask them to keep their assigned code, so 7700 is not always set. If they are not in contact, or want to be sure everyone sees them, they select 7700.

A controller who sees 7700 gives the flight priority over all other traffic, clears airspace around it, offers the nearest suitable airport and coordinates fire and rescue crews on the ground. Emergency equipment standing by at the runway is routine and precautionary, not a sign of how serious a situation is.

How 7700 appears on heywhatsflying

Our emergencies now page lists every aircraft in the US snapshot broadcasting 7700, 7600 or 7500, refreshed about every 15 seconds. The home dashboard shows the same count (usually zero to a few right now). Each entry links to the aircraft's live track on airplanes.live, where you can see whether it is descending, turning back or holding.

How common is it?

Across US airspace, a handful of aircraft squawk 7700 on a typical day, which is a tiny fraction of the roughly 45,000 flights the FAA handles daily. Many are airliners diverting for a sick passenger. Others are light aircraft with a rough-running engine, or business jets with a warning light. Tracker data also shows brief 7700 blips when a pilot rolls the knob through the code by mistake on older transponders, or when a squawk is decoded incorrectly.

Common myths

• "7700 means the plane is going to crash." No. It means the crew wants priority and help. The great majority land normally.
• "Every emergency squawks 7700." No. Many emergencies are declared by radio only, with the flight keeping its assigned code.
• "7700 and mayday are the same thing." They are related but separate. Mayday is a spoken distress call. 7700 is the transponder signal.

Related codes: 7600 (radio failure) and 7500 (unlawful interference). See all codes on the squawk code index, or learn to read the rest of a flight's data in how to read flight data.

Questions

Does squawk 7700 mean a plane is in danger?

It means the crew has an abnormal situation and wants priority handling. Most 7700 flights land normally, often at their destination or a nearby diversion airport.

Why does a plane squawk 7700 and then change back?

Sometimes the crew sets 7700 until they reach a controller, who then assigns a discrete code while still treating the flight as an emergency. Brief 7700 readings can also come from a mis-set transponder or a decoding error.

How many planes squawk 7700 each day in the US?

Typically a handful across the whole country, out of tens of thousands of daily flights. Medical diversions and precautionary engine or system issues are the most common reasons.