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I am aware that not all variants of the A320 are equipped with the HIGH ALT LANDING guarded push button. I know that it is pushed before landing at high altitude airfields. Was wondering what it does exactly?

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    $\begingroup$ Have you read this facebook post that suggests it's about affecting passenger oxygen masks? $\endgroup$
    – Mr R
    May 7, 2022 at 7:17
  • $\begingroup$ @MrR Interesting did not come across that. Thanks for sharing! $\endgroup$
    – Tap
    May 7, 2022 at 8:51

1 Answer 1

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The button raises the altitude at which the oxygen masks in the cabin automatically deploy. When landing at a high elevation airport, the masks might otherwise deploy during approach when the cabin pressure is reduced to the destination field pressure.

MASK MAN ON pb

The guard keeps this button in the AUTO position.

AUTO: The mask doors open automatically, when the cabin altitude exceeds 14 000 ft, or 16 000 ft if the HI ALT LANDING pb-sw is set to ON.
Pressed: The mask doors open.

HI ALT LANDING pb-sw

This pushbutton-switch changes the altitude threshold for the deployment of the passenger oxygen masks.

OFF: The masks drop, if the cabin pressure exceeds 14 000 ft (+ 250, -750 ft).
ON: The masks drop, if the cabin pressure exceeds 16 000 ft (+ 250, -750 ft).

(Airbus A320 FCOM - Oxygen - Fixed Oxygen System for Cabin - Controls and Indicators)

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  • $\begingroup$ So this button would only be needed at La Paz, Bolivia and a handful of Chinese airports above 13,250ft? $\endgroup$
    – njuffa
    May 7, 2022 at 23:24
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    $\begingroup$ @njuffa It isn't just the airport elevation. The approaches also have to be taken into account which are usually 2,000 feet above the surface. $\endgroup$ May 8, 2022 at 5:29

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