# Barometric Compensation Algorithm

**URL:** <https://discussions.flightaware.com/t/barometric-compensation-algorithm/45668>\
**Category:** ADS-B Flight Tracking\
**Created:** [February 7, 2019, 11:47pm UTC](https://discussions.flightaware.com/t/barometric-compensation-algorithm/45668 "2019-02-07T23:47:27Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![skygizmo](https://sea1.discourse-cdn.com/flex019/user_avatar/discussions.flightaware.com/skygizmo/32/92948_2.png) [@skygizmo](https://discussions.flightaware.com/u/skygizmo)\
**Post date:** [February 8, 2019, 12:12am UTC](https://discussions.flightaware.com/t/barometric-compensation-algorithm/45668/4 "2019-02-08T00:12:00Z")

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> [@obj](#):
>
> If what you want to know is height above MSL (or AGL, if you know the local terrain height) then a simpler approach for ADS-B equipped aircraft is to use the GNSS/GPS altitude, which is a geometric height above the ellipsoid and so is unaffected by pressure. (nb: you do need to adjust for the geoid height to get height AMSL, but that doesn’t vary a lot over smaller distances)

Yep. Just the MSL. I am not clear on if you are saying there is an option I can click that sill provide this info. Can you elaborate on what you mean by the ellipsoid?

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