UAV-1004270-001
41
Rev A
A.1.2 Transponder Status
In UCP-HD, the Transponder Status is sent in response to each Control
message, as documented in the ICD.
The presence of a fault to annunciate is delivered by the “Fault or Failure
Indicated” bit being set. To determine the specific fault, query the Heartbeat
message using a Message Request. The following specific fault indications
are available in the Heartbeat message, and should be mapped to
annunciations compliant with applicable regulations. TSO-C166b requires
annunciations of ADS-B transmission device and function failures (see
RTCA/DO-260B §2.2.11.5)
Fault
Description
Maintenance Required
ICAO address not set (RTCA/DO-181E §2.2.10.3)
ICAO address not set (RTCA/DO-260B §2.2.11.3.1)
Multiple position sources available
– check configuration
(RTCA/DO-260B §2.2.5.3)
Failure TX System
Transponder replies not enabled or acquisition squitter rate
failure (RTCA/DO-181E §2.2.10.4)
Transmit not enabled or extended squitter rate failure
(RTCA/DO-260B §2.2.11.2.1 and §2.2.11.5.1)
Failure GNSS No 3D
Fix
No valid 3D position from GNSS (RTCA/DO-229E §2.1.2.6)
Failure GNSS
Unavailable
Unable to communicate with GNSS subsystem (RTCA/DO-
260B §2.2.11.6)
