VORLOC against LOC

[KAG]

When are we established on the localizer?
1-When VORLOC?
2-When the localizer is alive?

[bfisk]

I don't quite understand your question, but I'd say as far as for when you are established on the localiser; when you are within half-scale deflection, and at a track that will require only minor adjustments to remain so.

[KAG]

I don't quite understand your question

I was not clear enough, I give you that.

On the 737, you are about to intercept the final approach course, the loc frequency is set, VORLOC is armed.
At what point you can say localizer captured, at what point you are established on the localizer?
1-When the localizer is alive, when you see on your PFD the loc becoming alive, and on your MFD set on APP mode you see the localizer alive (the needle turns magenta)?
2-When VORLOC turns green, vorloc captured?

[porch monkey]

Like he said. 1/2 scale deflection. That's the usual established criteria.

[Old Smokey]

You are established on any navaid facility tracking (LOC, VOR, NDB etc.) when within the tracking tolerances for that facility, and your tracking is such that you will be able to maintain this.

On that basis for a LOC, you are established, when, as earlier posters have indicated, you are within 1/2 scale deflection (1 dot).:ok:

A common error I frequently observe, is that many pilots will call "established" when the Flight Director or Auto-Pilot annunciates 'capture', this will frequently occur when still at full scale deflection. ATC are NOT aware or interested in your F/D or A/P modes, only that you are stabilised within the required tracking tolerances.:)

Regards,

Old Smokey

[KAG]

So the answer is when loc is alive, (one dot, alright), not when VOR/LOC turns green on the FMA right? (we are on the B737 here).

I was told that the VOR/LOC mode is more accurate than the actual localizer deviation indication and scale. Some pilot of my company will assume that we are established on the localizer (when on auto pilot) when VOR/LOC turns green on the FMA. And not before.

[Nightrider]

Listen to Old Smokey....your colleagues are on the wrong track. The 737 AP/FD "captures" (VORLOC green) as per intercept angle. On large angles this may happen even well before the CDI starts moving. There is, of course, also the distance to the facility involved.
You may be well off track at 20 NM with a green caption......

[KAG]

Thanks nightrider.
That is what I thought. Had a discussion in flight with a colleague the other day, the loc was alive, so I called loc established, pressed app, set the missed approach heading and altitude, but was told that the AP/FD (VOR/LOC green) was not captured when I called loc established, and that I should wait for it. Haven' t seen this information in the SOPs, so here I am asking.
Thanks for your answers guys.

[DFC]

KAG,

There are two separate issues in your last post.

1. When established. The answer to that is the same no matter what aircraft or what electronic systems you have. As said earlier, you are established when the LOC is within 1/2 scale deflection and going to stay within those limits. i.e. don't call LOC established when the LOC reaches 1/2 scale if you might shoot out the other side more than 1/2 scale during the turn.

2. Separate issue - managing the aircraft systems. Slightly different from aircraft to aircraft as well as from approach to approach. Your SOPs must be checked for this.

However,

Common practice in my experience is that the missed approach altitude is set when the aircraft starts descending. Setting the missed approach altitude well before that point removes the safety net of the altitude deviation warning.

From your comments it appears that your policy is to arm the LOC only when cleared to establish and then when established arm APP. In everywhere except the UK, I have no problem with arming APP when cleared for the approach, the aqircraft will establish on the LOC and descend on the GS. In the UK use LOC to establish unless given the clearance "when established descend on the GS".

Having said that, be aware of the GS position at all times. Some systems have a tendency to pitch up (climb) to the GS if you arm APP when the aircraft is 1/2 scale or less below the GS - this combined with having the missed approach alt set could cause you to level bust with no warning!!!!!!!

You say you set the Missed approach ehading and alt? OK if that is your SOP, my experience is that the heading bug is set to the heading that will follow the LOC on capture and updated as required during the approach. This means that should the LOC fail you can hit HDG and follow the same track and every missed approach starts on the final approach track i.e. a missed approach is always (even if it very briefly) started on the final track. I expect that you will use HDG for this initially.

So if the final approach heading is 270 and the missed approach heading is 360 (eg "straight ahead to 1000ft then right turn heading 360") do you really want to start the missed approach with the HDG bug set 90 degrees from where you are going at that moment? With the FD commanding a turn at 200ft when in HDG?

Just a few personal observations!!

SO everything under 2 is depending on your SOPs while 1 applies in every case.

[Nightrider]

DFC, when you arm the APP mode before the LOC capture is physically indicated this may lead, at least in some aircraft, to give you a handful of recovery work, nothing you want in IMC in a mountainous environment; reason is that some systems allow for descend with the G/S without being established on the LOC. On the 737 it is very simple, "cleared to establish on LOC" or "cleared for the approach" means arm the LOC, indication white.
Caption shows green asks for heading to RWY QFU.
When "cleared for approach" and when inside 1/2 deflection of LOC arm the APP, indication white. When G/S captured, caption green, reset altitude to initial G/A altitude.
Never give the automatics a chance to deviate from your altitude before you really want them to.