Hello all

Just want to make sure I am reading this correctly. AIP Gen 1.5 para 8.5.5.3 says that an RNAV approach using TSO C129 or C129a can now be used to satisfy the alternate requirements for navaids set out in ENR 1.1 para 58.3. Only that if an alternate is required for other reasons and I only have a C129 or 129a, I will need a ground based aid at the alternate.

Any help would be appreciated.
Thanks

Hi KF,

No, a TSO C129/129a cannot be used to satisfy alternate requirements.

AIP GEN 1.5 8.5.5.3 only says 129/145/146/196 GNSS receivers can be regarded as "radio navigation systems" as discussed in ENR 1.1 58.3 not that they automagically satisfy alternate requirements - in fact, AIP GEN 1.5-21 Table item (3) says only 145/146 and 196 units can be part of deciding whether you need an alternate of not. In other words, the C129 doesn't factor into the decision for an alternate. It is as if it doesn't exist.

Not only that but the Note in AIP GEN 1.5 8.5.5.3 explicitly states that, if you are using a TSO C129/129a unit and you need an alternate for whatever reason, that alternate must have an approach with a ground-based aid. Here they are essentially saying, you can't rely on an RNAV approach at the alternate if you only have a 129 unit.

So, a TSO 129 unit is a radio navigation system but it cannot be used for satisfying alternate requirements.

By the way, it is all a moot point really since after Febraury 4th next year, TSO 129 units aren't going to be much use to IFR pilots anyway. Virtually no 129 units talk to Mode-S transponders properly and these transponders are needed for ADS-B. ADS-B forms the surveillance component of PBN which is going to apply to all IFR aircraft very shortly.

Cheers,

Rich

Thanks a lot for clearing that up, and for the quick response.

Cheers