AIM Text
- If an aircraft with a coded radar beacon transponder experiences a loss of two‐way radio capability, the pilot should adjust the transponder to reply on Mode A/3, Code 7600.
- The pilot should understand that the aircraft may not be in an area of radar coverage.
Source: FAA Aeronautical Information Manual · current edition · paragraph 6-4-2.
The short answer
This AIM section is FAA advisory guidance telling a pilot whose transponder-equipped aircraft loses two-way radio capability to set the transponder to reply on Mode A/3, Code 7600. It cautions that the aircraft may not be within radar coverage, supporting lost-communications procedures under 14 CFR 91.185.
Research Notes
Common Questions
What transponder code do I squawk if I lose two-way radio?
The AIM advises adjusting the transponder to reply on Mode A/3, Code 7600 when an aircraft with a coded radar beacon transponder experiences a loss of two-way radio capability.
Does squawking 7600 guarantee ATC will see me on radar?
No. The AIM specifically notes the pilot should understand that the aircraft may not be in an area of radar coverage, so a 7600 reply is not a guarantee that controllers can observe the aircraft.
Is the 7600 squawk a regulation or advisory guidance?
This AIM section is advisory guidance describing what the pilot should do; it supports the lost-communications regulatory framework in 14 CFR 91.185 rather than itself being a rule.