For a while now I've noticed an exclamation mark on the ACARS inflight page of the B737NG at the beginning of a flight. It is located in the top left corner of the page and it just disappears after a while. I've been searching high and low what it means but can't find it. Any ideas?

ACARS page with !

  • 1
    $\begingroup$ I presume this is on a flight sim? $\endgroup$
    – Dan
    Commented Oct 19, 2015 at 8:07
  • 1
    $\begingroup$ No, it's on a real plane $\endgroup$
    – Ron
    Commented Oct 19, 2015 at 9:09
  • $\begingroup$ Not sure what options Boeing offers on the 737NG, but I assume this is a Honeywell product? $\endgroup$
    – DeltaLima
    Commented Oct 19, 2015 at 9:31
  • $\begingroup$ Yes, it's a Honeywell. FMC is 10.8 but I don't know if there is a specific acars/datalink version. $\endgroup$
    – Ron
    Commented Oct 19, 2015 at 9:40
  • 5
    $\begingroup$ If it is company specific, and if you're allowed, please be sure to come back to tell us what it means. Feel free to answer your own question. $\endgroup$
    – FreeMan
    Commented Oct 19, 2015 at 14:21

1 Answer 1


Okay guys, the verdict is in.

It is a symbol to indicate the crew alerting chimes are inhibited. From OUT (off block) until OFF+15 and estimated ON-10 until IN (on block) the chimes to alert for new data and messages are suppressed to avoid nuisance warnings during critical flight phases.

Happy landings!

  • $\begingroup$ On other FMC configurations, the chime is only inhibited below some flight level, e.g. FL230. $\endgroup$
    – mins
    Commented Oct 25, 2015 at 3:26

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