A320 RWY TRK mode
 

Hi all,

I’ve come to ask this question here as I don’t believe the FCOM shows an accurate representation of what may actually happen when you take off and RWY TRK engages… as the diagrams show OP CLB being armed which I don’t think is a function on the 320…. Anyways….


My query:

if you have in the f-plan, no Sid, just the departure rwy inserted which has say a 1000ft pseudo CF wpt on the extended centreline after departure.
if I disarm nav on the ground, I would expect RWY TRK engagement at 30ft.

Once I’ve reached the pseudo 1000ft waypoint if I don’t do anything will the aircraft drop into hdg?
or will it remain in RWY TRK indefinitely until I change the mode by either pulling hdg or doing a direct etc…


thanks everyone, hope you all have a good weekend

The disengagement conditions for RWY TRK will be listed in the Aircraft Systems section of the FCOM. I’m 330, so it might be different to the 320, but my FCOM says:

RWY TRK disengages, when one of the following occurs:

• The flight crew pulls the HDG/TRK knob: HDG/TRACK engages.
  
• NAV is armed, and the aircraft reaches the capture zone of the active leg: NAV engages.
  
• The flight crew inserts a DIRECT TO waypoint: NAV engages.
  

So in your example, it will remain in RWY TRK until you pull hdg etc.​​​​​​​

A320 is identical to the above.

Pilotbrandon7606 is there a reason you don't believe what the FCOM says? OP CLB armed is definitely a function of the A320. See:
So if NAV is not armed for take-off, you will have OPN CLB armed rather than CLB.

Ask yourself why you think any mode will change when you ‘pass’ the 1000’ pseudo waypoint. You are not actually tracking to that waypoint, you’re not in NAV, you are in RWY TRK. So why would any mode change abeam some random point?

Agreed with the above posters, I think they have written enough proof. By the way, it will certainly go to OP CLB after the pseudo-waypoint, tried this myself in real life on a visual departure (i.e ATC clearance was climb RWY heading and at 4000 turn left DCT to XXX), so we decided to give it a go.

whenever I have seen it IRL, nav is disarmed and CLB stays armed, but OP CLB actually engages.

i was under the impression it couldn’t arm on the 320, only on the wide bodies. Happy to be proved wrong though

Open climb can’t be armed on the A320 but the vertical mode will revert to open climb if climb is no longer possible, ie lateral mode changes from nav to hdg/trk.

You’ll get the triple click and a boxed FMA when this happens.

When would it be acceptable to fly runway TRACK if given a clearance to fly runway Heading? With parallel runway departures and a stiff cross wind the upwind aircraft flying runway heading may drift into conflict with the downwind aircraft flying runway track.

If you are asking in my case in particular, it was a single runway airport in the middle of nowhere.
And you have a very valid point: In airports where parallel departures are taking place, as it happens at some places and sometimes in the US, needless to say I fly a heading.

On the other hand, would you want to be blown towards downwind when ATC asks you to maintain runway heading? This is a never ending ambiguous discussion.
Airbus in their wisdom have given priority to fly on the runway track and I think that makes a lot of sense in the real world, whatever side you take in this discussion ;)

Well, if ATC clears You to maintain a heading, is not this what they want and expect You to comply with, with all its consequences? If they don´t like the drift the wind imposes on one of the aircraft under their control, they can always amend the heading "for drift correction", as some units tend to explain when giving such instructions.

If they had wanted runway track, they could have given such a clearance instead. I guess that they don´t do this because they are aware that not all aircraft are able to accept an ad hoc "track" clearance. Consider a 320 (able to fly a cleared track) and a Dash 8 (unable for a track) departing parallel runways, both cleared for runway heading, and the 320 crew decides to use track instead. All it takes is a matching crosswind for the tracks to converge. With proper headings, both would be subject to roughly the same drift.

In the US, you NEVER correct for wind. You’re over-thinking it and putting yourself in a dangerous situation.

You fly the HEADING that’s assigned. If wind is a factor, you’ll be given a heading that accounts for the wind.

It's not ambiguous, it's clearly spelt out in the rules. Heading means heading. If you drift, so be it, everyone else SHOULD be drifting as well.

I fully acknowledge that yet it’s not always that black and white. Like the response above, the most ‘maintain runway heading’ instructions I receive actually imply ‘fly straight ahead’. But again, I’m not dismissing what you say.


Question: how would you deal with ‘maintain runway heading’ when you depart in, say, a lefthand 38 knot crosswind. You will initially fly runway track until you pull heading. But by then your nose will be into the wind so you will actively have to turn 20-25 degrees to the right to end back on runway heading! Which is quite large a correction..

Yep. That's what they've asked for so that's what you give them. They know the wind is there. If they don't like the result they can give you a new heading.

Things differ between airports. At Cairo with its 3 parallel runways, the clearance is typically for runway heading, 6000ft, contact radar. So heading it is and let ATC sort out the drift. Other airports, like the slightly more mountaineous Tehran (29R/L with L being a secondary taxiway in practice most of the times) require runway track and there even is a corresponding SID: IKA1A reads "Fly runway track, climb 7000ft, contact radar when airborne and expect vectors". No need to overthink it - the clearance is given, confirmed, accepted by the Captain, and will be flown.

For those advocating flying a track when cleared a heading: what do You do when instructed by London approach to e. g. leave Lambourne on heading 265? Will You fly the cleared heading then or will You introduce a wind correction on Your own and deviate from Your clearance? If You follow the clearance in this case and fly the heading, letting ATC sort out the separation, what makes the heading when airborne different?

(my bold)

https://www.faa.gov/air_traffic/publ...CG_7-24-14.pdf

That's the way to go!

By the way I think the thread might have drifted a little. I am with PENKO on what he said, not every airport is the same, not everywhere is the same, not all the crosswinds are to the max, not every time there are parallel departures. We apply airmanship and we adjust our operation on what we see/feel the safest course of action. In busy airports we try to be on top of the game, on smaller airports at nowhere with single ops and one take-off/arrival every hour, we tend to relax a little.