[2.9.5.55918 MT] TACAN warmup/synchronization issues

[Stickler]

When entering the cockpit, having external power connected, switching on the engine master switches, setting generators to EXT ON and switching on the Instrument Ground Power switch, I found three cases of which only case 1 produces the expected result.

1) Without a human WSO in the jet, leave the rear TACAN in OFF and switch the front TACAN to T/R. The NAV CMD light will illuminate in REC and T/R. TACAN warmup will complete in approximately 2 minutes. Subsequently switching the rear TACAN to T/R does not produce any unexpected results.

2) As 1), but instead of switching on the front TACAN, leave it in OFF and switch the rear TACAN to T/R. No NAV CMD light illuminates in the rear (and front) cockpit, neither in REC nor in T/R. TACAN warmup does not take place. Switch the front TACAN to REC (or T/R). Note that the front NAV CMD light illuminates both in REC and T/R. Warmup completes in about 2 minutes.

3) With a human WSO in the jet, switch the front TACAN to T/R. Observe that the front NAV CMD light will illuminate only in REC, not in T/R. Switch the rear TACAN to T/R. The rear NAV CMD light will not illuminate, neither in REC nor in T/R. TACAN warmup does not take place. To initiate warmup, the front TACAN has to be recycled to OFF, then back to REC (or T/R).

To avoid the issue altogether, human WSOs have to switch their TACAN to REC (or T/R) before the pilot. Waiting for the completion of warm-up before switching on the front TACAN is not required.

Edited July 2, 2024 by Stickler

[Bazz_Mulder]

Bumping this thread as the issue is still there.