Add field elevation command or indicator

[JPmAn24]

I usually tell aircraft to descend to 2000 ft above field elev, and I sometimes forget what the field elevation is.

Suggestion: do either of two things:
**1: **Add a new command (for example: "fieldelev") that shows the field elevation as a response, kind of like the "sa" command does

**2: **Add a indicator next to the terrain elevation legend

[erikquinn]

Option 2 sounds pretty good! Perhaps we could stick that with some basic weather we ought to be displaying. Maybe a simple bit of text we could shove in a corner somewhere (or hide/show) which includes the field elevation for the convenience of the controller. Just spitballing, but maybe something like this?

WIND  | 03017G24
ALTIM | KSEA 2992
ELEV  | KSEA 433

[JPmAn24]

Just like that. Perfect.

[n8rzz]

For whomever implements this, please do not tie this in to the CanvasController. This should be its own thing separate from the CanvasController.