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"Error message: Surveillance Equipment (ICAO): “B1” is invalid" causes an error due to the absence of a listed transponder.

ATC requires a transponder code included in the ICAO Surveillance field in order for the flight plan to be accepted. The transponder code must be one of these:

     A, C, E, H, I, L, N, P, S, or X

Here are the most common codes installed in aircraft.

     A - Mode A only (no altitude)

     C - Mode A and C

     S - Mode S, Aircraft ID and Altitude

     E - Mode S, Aircraft ID, Altitude, Extended Squitter (Most ADS-B Out transponders are this code)

     L - Mode S, Aircraft ID, Altitude, Extended Squitter, EHS

Examples of transponder and ADS-B Out systems with recommended ICAO Surveillance codes are listed in the table below:

Note: If you just file an ADS-B code such as B1, B2, U1, or U2 and do not also include a transponder code, your flight plan will be rejected. All flight plans must file a transponder code!