12
$\begingroup$

I just saw a YouTube video with an A340 landing. There were the regular altitude callouts (1000, 500, etc.) until the callout "110". I was quite puzzled by this.

What are the conditions that the automatic callout would call "one hundred and ten" instead of one hundred?

Parenthetically, I'm almost certain - though I can't recall the details right now - that I've also heard a callout "seventy" in some other video, possibly with another plane type.

$\endgroup$
18
$\begingroup$

From the same channel and also an A340 at 4:26 in this video the standard '100' can be heard.

The reason is a built-in timeout, if a certain time elapses between callouts—say due to non-standard [shallower] descent rate, perhaps due to high headwind for example—the current height is called out. In other words, you get to hear a callout at regular intervals.

From an A340 manual, here is the bit about the intermediate callouts:

enter image description here


Just a bit of history: one of the early TAWS systems (Mk II I believe) had a rising tone instead of the 100, 50, etc., you can watch it here.

Note on terminology: those callouts are heights (radio), not altitudes (barometric).

$\endgroup$
  • 2
    $\begingroup$ What a great answer, cheers! $\endgroup$ – Digital Dracula Jan 1 '18 at 5:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.