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How to fly this ILS? without DME?

I’ve never flown a timed approach and I’m very sure I’d never do it in IMC. If I’d really be in the situation that a) GPS fails, b) ILS fails and at the same time c) DME fails, I’d have ATC radar vector me to the next military airport and do PAR approach.

a, b and c have already sufficiently demonstrated to me that this is for sure not my lucky day so that I’d not bet my life on having luck with such a timed approach.

Germany

Ibra wrote:

Do you have to overfly VOR or stay on LOC?

Mooney_Driver wrote:

Actually, how far off is it? Would you see a deflection?

Looking at the chart, it appears to be less than 0.2 miless off the centreline. So the localiser path leads through or is close to the “cone of silence”; in practice I would (a) look at the moving map; or on legacy dials, (b) set the VOR receiver to a radial 131 or 311; it will be pretty obvious that way when you get abeam the thing; the needle flicks from one side to the other with or without a brief red flag. That is confirmation you went past it.

Biggin Hill

Malibuflyer wrote:

I’ve never flown a timed approach and I’m very sure I’d never do it in IMC.

If you have a reasonable GPS, you fly timed approaches using the GPS with the primary aid (NDB or LOC) tuned to cross check. On the Garmin navigators, you would simply load the procedure, DISABLE automatic switching from GPS to VLOC, and fly it. You manage the descent the same way as you would on a GPS approach, including any vertical guidance the navigator gets you.

To cross check you should set NAV2 to show the localiser, but keep the NAV1 indicator on the GPS.

But that answer is boring…

Biggin Hill

Mooney_Driver wrote:

Actually, how far off is it? Would you see a deflection?

Under 1/4 dot, examiners tolerate +/-2.5 dots

Cobalt wrote:

This is safe – the purpose of the FAF is to provide an error check to catch gross altimeter setting errors, false glideslopes or misdialed nav-aids, so as long as you have that position check before you go below 2,420ft after ROUBO you don’t bust anything… you just respond that you arranged your descent to arrive at/abeam the VOR at 2,420 and were never below the profile, so there

I think that makes life more easier at Rouen…it’s a brave bold move in non-DME LOC Y 26 at Lille, you descend from 2000ft to 1380ft?

Malibuflyer wrote:

a) GPS fails, b) ILS fails and at the same time c) DME fails…I’d have ATC radar vector me to the next military airport and do PAR approach.

Well that is really unlucky there are no radar services at Rouen bellow 3000ft and the military at Evreux & Villacoublay stopped offering PAR, nearby one is 200nm south-east at Avord…if a, b, c fails, I would just hand myself to the ground, ‘I am sorry Goose’ like in Top Gun

Cobalt wrote:

If you have a reasonable GPS, you fly timed approaches using the GPS with the primary aid (NDB or LOC) tuned to cross check. On the Garmin navigators, you would simply load the procedure, DISABLE automatic switching from GPS to VLOC, and fly it. You manage the descent the same way as you would on a GPS approach, including any vertical guidance the navigator gets you.

Well it’s not easy on this one, pressing direct ROUBO in GPS FPL, I get ‘approach not active’ no LNAV+V, the missed procedure goes missed and the GPS approach is toasted…it works if you have loaded & activate an IAF (activate ROUBO-FAF leg) or activate in vector-to-final VTF mode (removes ROUBO from extended line) and now you need glass-cockpit with 3×CDI: ROU VOR, LNAV GPS and RN LOC

The direct ROUBO (this is not an IAF) has to be done along LOC axis, ROUBO is 1.7nm from FAF, that is too close for GPS/FMS mechanics and also too short an ATC vectoring instruction

Last Edited by Ibra at 17 Nov 12:47
Paris/Essex, France/UK, United Kingdom

Cobalt wrote:

it will be pretty obvious that way when you get abeam the thing; the needle flicks from one side to the other with or without a brief red flag. That is confirmation you went past it.

Exactly. that is what I meant and expect, looking at the chart.

LSZH(work) LSZF (GA base), Switzerland
15 Posts
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