I got the error message “Surveillance Equipment (ICAO): “B1” is invalid.” What do I do?

"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:


Device Filing Codes
   KT 74 E, B1 
   KT76A  C
   Ranger XVR with mode A/C transponder C, U2 
   Ranger Lite with mode A/C transponder  C, U1



  GTX 330ES

 E, B1

  GTX 335

 E, B1

  GTX 335R

 E, B1

  GTX 345 

 E, B2

  GTX 345R

 E, B2

  GDL 88/84 w Mode S transponder

 S, U2

  GDL88/84 with Mode A/C transponder

 C, U2



  Lynx NGT-9000 series

 E, B2
  Stratus ESG - file E, B1
  TT31 E, B1

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!