Fenix A320 autoland questions

[srce 57]

I've tried a couple of autolands to ILS08R EGKK in the Fenix A320. A couple of questions:

- With managed speed, the speed comes down to green dot and I put in flaps one - but then the speed doesn't come down to S speed. This chart https://www.smartcockpit.com/docs/Airbus_A320-ILS_Approach_Landing.pdf  and a couple of other things I've read suggests to me it should.

- After landing, I see Rollout displayed and both APs are on, but the aircraft doesn't seem to hold the centre line - it veers a little bit left.

Any ideas what I might be doing wrong? 

[Fiorentoni 4,270]

2 minutes ago, srce said:

I've tried a couple of autolands to ILS08R EGKK in the Fenix A320. A couple of questions:

- With managed speed, the speed comes down to green dot and I put in flaps one - but then the speed doesn't come down to S speed. This chart https://www.smartcockpit.com/docs/Airbus_A320-ILS_Approach_Landing.pdf  and a couple of other things I've read suggests to me it should.

- After landing, I see Rollout displayed and both APs are on, but the aircraft doesn't seem to hold the centre line - it veers a little bit left.

Any ideas what I might be doing wrong? 

Not sure, it works for me (haven't tried autoland, though).  Has the aircraft entered APPR phase on the PERF? For me it always goes down to S speed once I set flaps 1 on approach.
Maybe do a short video on final approach, otherwise it's hard to say what's wrong.

[srce 57]

https://youtu.be/AjobHR_4LQA

Flaps 1 at 12:05 - at 12:40 there seems to be no further deceleration towards S

Loses centre line during rollout at 15:50 - Also, why no TCAS warning here? "TA only" is on the ND.
 

[Fiorentoni 4,270]

9 minutes ago, srce said:

https://youtu.be/AjobHR_4LQA

Flaps 1 at 12:05 - at 12:40 there seems to be no further deceleration towards S

Loses centre line during rollout at 15:50 - Also, why no TCAS warning here? "TA only" is on the ND.
 

On the ground it's only TA, you don't need to hear "climb climb" when on the runway...

As for the S speed: Thanks for the video, that explains what you are doing "wrong". When on the glideslope, the glideslope has priority over the speed target. So in simple words: The aircraft is trying to hold the glideslope and therefore descends so much that speed does not drop enough to get to the S speed. Obviously speed is much easier to handle than losing the glideslope (-> mandatory go around), so that's a smart choice by the Autopilot.
Why is it a user error? You absolutely have to be on flaps 1 and down to S speed BEFORE the FAF (= glideslope capture). Otherwise you have to drop gear early to reduce speed, but that's inefficient.
So 5-10 nm before the FAF / before the GS capture, go flaps 1 and speed will drop to S speed. Then all will be fine.

EDIT: as for the "rollout" issue, worth creating a ticket. It does indeed veer sliglty to the left on the runway and it shouldn't.

Edited May 22, 2022 by Fiorentoni

[srce 57]

14 minutes ago, Fiorentoni said:

So 5-10 nm before the FAF / before the GS capture, go flaps 1 and speed will drop to S speed. Then all will be fine.

Ok - but isn't the aircraft too fast at that point? It only gets to the green dot at the FAF.

Thanks.

Edited May 22, 2022 by srce

[polosim 857]

In a side note, not entirely related with your 'issue' :

Attitude Indicaton ( SBY HORIZON ) is mandatory and a requirement for this operation ( AUTOLAND and others ).

To reset SBY attitude indicator pull and hold white knob :

 

 

[Fiorentoni 4,270]

1 hour ago, srce said:

Ok - but isn't the aircraft too fast at that point? It only gets to the green dot at the FAF.

Thanks.

This depends on a lot of factors, like STAR constraints, tailwind, aircraft weight. VNAV isn't perfect (in real life either; a sudden wind change can mess you up), so if you are coming in too fast, you as the pilot need to do one of the following:

a) Go flaps 1 early, like at the deceleration point as soon as you reach 235 kts (which I think is the max. speed for flaps 1). This will add a lot of drag and slow you down considerably, so you reach the FAF in most cases at S speed.
b) Manage your speed early, like slow down to 220 already before the deceleration point. Or just use speed brakes at the deceleration point, that's probably the easiest thing.
c) Say "I don't care, I'll just configure early" and start the glideslope too fast but just go flaps 2 and gear down much earlier.

In real life c) not uncommon, because many times ATC will want you to stay fast at 180 kts for the first part of the final approach (for separation reasons). So pilots have no choice anyway.

Keep in mind VNAV can only control descent rate and thrust level; it cannot use speed brakes or gear down or flaps, so it does not have all the means it needs to get out of unforeseen situations.