Use of II=14
NISC Operating Procedures for Test, Research and Development (TRD) Interrogator Codes
Interrogator codes for Mode S radars are very limited. Therefore, all Test, Research and Development (TRD) radars are assigned a shared interrogator code: II 14. In order to avoid unnecessary RF pollution in the 1090 MHz band, TRD radars use permanent lockout in their entire coverage, and are not allowed to use All Call lockout override.
This is a restrictive mode of operation which can produce detection problems when two or more TRD stations with overlap transmit concurrently. Therefore, if a TRD operator requires guaranteed detection for limited trials, they can notify the NISC, who will co-ordinate with overlapping TRD operators to make sure that they do not transmit at the same time.
When a TRD operator doesn’t need guaranteed detection, they can transmit without prior co-ordination, as long as they do not conflict with critical operations co-ordinated by others.
If a TRD operator needs to operate for longer periods with guaranteed detection (for transponder monitoring for instance), they should apply for a temporary distinct code allocation, using the normal code allocation request procedure.
If a TRD operator needs to use modes of operation that are normally not allowed on code 14 (such as lockout override), they should apply for an exemption, using the normal code allocation request procedure.