I saw the shortcut CPLD on this altitude alerter from a Cessna 210, and could not work out what it could possibly mean:

Altitude alerter

What does it mean on this altitude alerter, and if CPLD is also used elsewhere in aviation, what does stand for there ?


1 Answer 1


The unit in the image is a Cessna AA-801A altitude alerter.

CPLD Green Lamp:

Lights when airplane reaches selected altitude and Integrated Flight Control System altitude hold mode is automatically engaged

CPLD would be short for coupled, indicating a system is linked to the autopilot.

You can see this and read more in this C210 POH, page 559 in the pdf (Supplement 47, page 4).

enter image description here

  • 2
    $\begingroup$ Ahh … Maybe I should read both the P210N and the T210N POH in the future - there seems to be a lot of information in the latter that isn't in the former. Thank you very much ! +1 $\endgroup$
    – TheEagle
    Dec 15, 2021 at 23:02

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