Hey Bob and Co,

Just trying to get my head around this one.

It states that you are "tracking on the LOC" and have the "VASI lights in sight". So in AIP 1.14.6 b it states that you may descend within 5nm if aligned with runway centreline and established on slope on the VASIS or 7nm for a runway equipped with ILS/GLS.

The 10nm is if you're established on the ILS/GLS path. So how is the answer 10 miles when the question only states you're tracking on the LOC? It also doesn't state that you're established on slope of the VASIS so that doesn't seem like an option either.

Could you please provide some more info on this one.

Thanks

Tracking on the LOC is the ILS path, you track the LOC with the G/S being your VNAV.

- 10nm being on LNAV with the ILS path (aka LOC)

Hmm are you sure? I thought you could track on the LOC but use the DME or GNSS for distance and the Altimeter for height at certain distances. In the AIP is states "10nm of the aerodrome, established not below the ILS/GLS glide path with less than full scale azimuth deflection". This question says nothing about being established on the glide path

Glide slope G/S = vertical guidance
Localiser LOC = lateral guidance

You can be on an ILS/LOC IAP using only the LOC and no G/S

The DME dist and Altimeter have no relevance for this question.

Your CDI shows you “tracking” on the LOC

Therefore you are establish on the LOC Approach

To avoid further confusion on this question see AIP ENR 1.5 para 1.14.5 b(ii) that says you don't have to be established on the glide path. All you need is to be not below the glide path, and have less than full scale 'fly up' deflection on the glide path indicator (remember you are flying visually at this stage). I have amended the wording of the question text to say that. The answer remains 10nm.

Awesome thanks for the clarification Bob!