If you are flying in nav mode, then atc tells you turn to a different heading, as soon as you change the heading knob the aircraft starts turning, then why do i need to pull it?

  • $\begingroup$ What does the FMA say when your rotate the heading knob without pulling? $\endgroup$
    – Bianfable
    Dec 15, 2022 at 7:31
  • $\begingroup$ The FMA remains in NAV mode until you pull the knob out. $\endgroup$
    – Jan
    Dec 15, 2022 at 8:35

1 Answer 1


When you are in NAV mode the heading indication on the FCU is normally dashed (---*). Then, if you just rotate the knob it first synchronizes the heading to the current heading, then displays the selected heading value and you can pre-select it in the FCU. But it remains in NAV mode and there still is the managed dot after the selected heading value in the FCU (e.g. 270*) until you pull the knob out. When you pull the knob it goes to HDG or TRK mode and the managed dot in the FCU disappears (e.g. just 270 without dot) and only then does the aircraft initiate the turn towards the selected heading.

  • If you do not pull the knob then the heading value will disappear after a while (45s or so) and the FCU heading will be dashed again.

  • Once you are in HDG or TRK mode you can just rotate the selected heading knob and the aircraft will immediately turn. You don't need to pull it again.

It's the same for the selected airspeed and selected vertical speed. You can rotate the knob to pre-select a value but you have to confirm the change to selected mode by pulling the knob.

  • $\begingroup$ But , why can't I just rotate knob in managed mode and then fly my desired heading without pulling? what happens if i continue to follow atc radar vectors but don't pull it but keep on changing the knob ? $\endgroup$ Dec 15, 2022 at 17:02
  • $\begingroup$ it starts turning as soon as i change the knob, even without pulling it $\endgroup$ Dec 15, 2022 at 17:04
  • 2
    $\begingroup$ @SachinChaudhary Are you talking about a simulator or the real aircraft? I'm fairly certain it won't turn in NAV mode when rotating the knob. $\endgroup$
    – Bianfable
    Dec 15, 2022 at 18:15
  • $\begingroup$ FCOM is available online if you want to read the real documentation: smartcockpit.com/aircraft-ressources/A320-Autoflight.html $\endgroup$
    – Jan
    Dec 16, 2022 at 9:24

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