When to set the Missed Approach Altitude?

[212man]

I see that in both the Airbus and Boeing FCOMs, it is suggested not to set the Missed Approach Altitude until below it. Other than when anticipating further descents towards the approach, I can't see why this would be. e.g. you are at 3000 ft intercepting the localiser, why not set the Missed Approach Altitude of 2500 ft then, in the spirit of anticipation and forward planning?

I'm not being type specific, so maybe there is a problem in doing this on some types (ALT capture?) but I'd be interested to know peoples thoughts.

[Intruder]

Our procedure (747 Classic) is to set MAP at the Final Approach Fix. After that, we are using Glideslope or Vertical Speed for vertical guidance, so Altitude Capture is not a problem and setting an altitude other than the "target" altitude will not affect Flight Director guidance.

If you are at level at 3000' intercepting the localizer, cleared for the approach, and Altitude Hold (or your equivalent) is engaged, the MAP could be preset after ILS mode is selected and prior to G/S capture.

[212man]

Have just spoken to a colleague who flew 737NG and 320/319 and the answer seems clear. On the 737 passing the altitude set will activate a loud claxon, warning you, and on the 320 setting the altitude arms its capture. I'm used to types where setting the ALTP (Preselect) is there for use later once you arm it's capture.

[Gullyone]

Most A/C I have flown set GA alt during the landing checks when established on the glidepath, or on a NPA it can vary due to the neccesity of arming V/S prior to the decent if the G/A alt is the same or lower than the platform alt.

[A Very Civil Pilot]

737 - If you're at 3000' and capture the g/s, there is nothing to stop you setting g/a of 2000'. It won't capture at 2000', as you are in app mode.

For an NPA we now set MDA in the alt window, and once more than 300' below g/a alt reset that into the window.

In all cases the 1000' point is the reminder to check it is set.

[Dream Land]

and on the 320 setting the altitude arms its capture Not if you have intercepted an ILS G/S, after intercepting a glide slope it will ignore any altitude selected that is below your present altitude, we set our Missed Approach altitude at G/S intercept or at the FAF for a non precision approach.

[TACHO]

On a precision approach one would normally set the go around altitude at GS* (ie the aircraft is capturing the glideslope and will then ignore any altitude that is set in the FCU window). However when doing a visual approach or a non precision approach we normally set the GA alt once we are below it.

It gets a little bit disconcerting when you are descending with a horn blaring down your lughole and you ahven't got a bug to prompt you when to stop the descent. And with the Airbus especially ALT* can be the most annoying annunciation when you are trying your very best to descend at a reasonable rate.

Tacho

[Spooky 2]

I think Boeing is pretty clear about this issue in the repective FCOMS. For instance on the B777.

Set the MAP after capturing the GS, or on a VNAV approach when at least 300' below the MAP altitude, or if your using VS or FPA you should set the MAP when you are within 300' of your DA/MDA. Various operators may have modified this data to suit their operations along with the respective authorities approval.

I think the best practice requires standardization within your respective airline protocols and procedures. Freestyle methods usually bring with them unexpected consequences!

[Propellerhead]

Probably the thing I forget most often! Tend to do it at glide capture but sometimes gets missed during hand flying, visual or non precision approach during high workload. Perhaps should check it as I check '5 greens' on short final.

[flyboyike]

Our procedure (new one, actually) is for the PNF to call "500' Above" (meaning, 500' above MDA), whereupon the PF will respond "Set Missed Approach Altitude".

[mike wess]

A320/330/340 setting the GA altitude on an ILS approach is done when you get glide slope * (star) on the FMA, if you are doing a non presicion approach set the GA altitude when crossing the final approach fix. On a visual approach and your are cleared for a visual appraoch leave the altitude window on circuit altitude.

[Carlos Gómez-Mira Ga]

This is the best procedure in all airplanes