A system for on-wing test of a transponder (XPDR), comprising: an Airborne Collision Avoidance System (ACAS) onboard an aircraft, the ACAS including a Traffic Computer, at least one Traffic Computer antenna (122,124), and a XPDR fail indication; at least one XPDR onboard the aircraft, the at least one XPDR operatively coupled with at least one XPDR antenna (132,134); the at least one traffic computer antenna and the at least one XPDR antenna separated by at least one antenna range (210, 212); a test input coupled with the Traffic Computer, the test input configured for enabling a test of the at least one XPDR; the Traffic Computer and the at least one XPDR each operatively coupled with a suppression bus; the Traffic Computer including a tangible, non-transitory memory operatively coupled with the Traffic Computer and configured to provide the Traffic Computer with a plurality of XPDR system configuration data including at least one of a cable loss, the at least one antenna range (210, 212), and a XPDR class, the tangible, non-transitory memory having instructions stored therein that, in response to execution by the Traffic Computer, cause the Traffic Computer to: receive a test command from the test input to enable the test of the at least one XPDR; disable the suppression bus; execute the test of the at least one XPDR, including a plurality of XPDR tests via at least one Radio Frequency interrogation of the at least one XPDR, the plurality of tests including all of: a radio reply frequency test based on the XPDR class, a suppression test, a receiver sensitivity test including a loss factor for each of the cable loss and the at least one antenna range, a RF peak output power test including the loss factor, a Mode S diversity transmission channel isolation test, a Mode S address test based on a XPDR address, a Mode S format test, a Mode S all-call interrogation test, an Air Traffic Control Radio Beacon System (ATCRBS)-only all-call interrogation test, and a squitter test; re-enable the suppression bus; and illuminate the XPDR fail indication and store failures in a fault memory if at least one of the plurality of tests fails. an Airborne Collision Avoidance System (ACAS) onboard an aircraft, the ACAS including a Traffic Computer, at least one Traffic Computer antenna (122,124), and a XPDR fail indication; at least one XPDR onboard the aircraft, the at least one XPDR operatively coupled with at least one XPDR antenna (132,134); the at least one traffic computer antenna and the at least one XPDR antenna separated by at least one antenna range (210, 212); a test input coupled with the Traffic Computer, the test input configured for enabling a test of the at least one XPDR; the Traffic Computer and the at least one XPDR each operatively coupled with a suppression bus; the Traffic Computer including a tangible, non-transitory memory operatively coupled with the Traffic Computer and configured to provide the Traffic Computer with a plurality of XPDR system configuration data including at least one of a cable loss, the at least one antenna range (210, 212), and a XPDR class, the tangible, non-transitory memory having instructions stored therein that, in response to execution by the Traffic Computer, cause the Traffic Computer to: receive a test command from the test input to enable the test of the at least one XPDR; disable the suppression bus; execute the test of the at least one XPDR, including a plurality of XPDR tests via at least one Radio Frequency interrogation of the at least one XPDR, the plurality of tests including all of: a radio reply frequency test based on the XPDR class, a suppression test, a receiver sensitivity test including a loss factor for each of the cable loss and the at least one antenna range, a RF peak output power test including the loss factor, a Mode S diversity transmission channel isolation test, a Mode S address test based on a XPDR address, a Mode S format test, a Mode S all-call interrogation test, an Air Traffic Control Radio Beacon System (ATCRBS)-only all-call interrogation test, and a squitter test; re-enable the suppression bus; and illuminate the XPDR fail indication and store failures in a fault memory if at least one of the plurality of tests fails. receive a test command from the test input to enable the test of the at least one XPDR; disable the suppression bus; execute the test of the at least one XPDR, including a plurality of XPDR tests via at least one Radio Frequency interrogation of the at least one XPDR, the plurality of tests including all of: a radio reply frequency test based on the XPDR class, a suppression test, a receiver sensitivity test including a loss factor for each of the cable loss and the at least one antenna range, a RF peak output power test including the loss factor, a Mode S diversity transmission channel isolation test, a Mode S address test based on a XPDR address, a Mode S format test, a Mode S all-call interrogation test, an Air Traffic Control Radio Beacon System (ATCRBS)-only all-call interrogation test, and a squitter test; re-enable the suppression bus; and illuminate the XPDR fail indication and store failures in a fault memory if at least one of the plurality of tests fails.