Without doing the math, how do you know your true altitude AGL when your altimeter is set to MSL

  • 3
    $\begingroup$ The math isn't that difficult: subtract the field elevation $\endgroup$
    – Sean Huber
    Mar 27, 2018 at 21:19
  • $\begingroup$ Are you asking about an aircraft in flight or sitting on the ground? See this question too. $\endgroup$
    – Pondlife
    Mar 28, 2018 at 1:17

1 Answer 1


I usually don't care a lot about my AGL altitude.

When I'm doing my flight planning on the ground, I do take into account terrain and obstacles, and pick appropriate MSL altitudes to be well clear of anything on the ground.

But by the time I get in my plane, I'm thinking in terms of MSL (altimeter) and no longer about AGL.

That even applies to approaching my destination field. If I know the field is at 1,500 ft. and I want to do a traffic pattern at 1,000ft. AGL, then I plan for my altimeter to read 2,500 (MSL). And I think about if I'm at the proper MSL altitude (2,500), not what my AGL altitude is.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .