Squawk 7700意思
"Squawk 7700" is a transponder code used by aircraft in emergency situations. The transponder is a device on an aircraft that sends out signals to air traffic control (ATC) and other nearby aircraft. By selecting 7700 on the transponder, the pilot is signalling that they are in distress or have an emergency.
When ATC sees a transponder code of 7700, they know that the aircraft is in trouble and will respond accordingly. This could mean rerouting other aircraft to give the distressed plane more space, providing emergency assistance, or any other appropriate action.
The numbers 7700, 7600, and 7500 are all used as emergency codes. 7700 is for a general emergency, 7600 is for a loss of radio communication, and 7500 is for a security-related emergency, such as a hijacking.