-1 for Altitude Data


Hi Everyone - I’m completely new to this and completely new to FlightAware data. I am an engineer and I received an output of FlightAware data from a colleague. It has fields with -1 for an altitude. Anyone know why this might be? Is it a valid field value for Altitude (if so, what does it indicate) or is it possible the output I have has been corrupted? Thanks!


Could it be the output for “on the ground”?


I was making the assumption that on the ground was 0 but that’s totally an assumption (and we all know making assumptions is bad). Maybe -1 means no data available?


What API are you using? Generally we omit altitude if it’s not available, we don’t use -1. Negative altitudes are possible and valid, but typically you’ll only see them in multiples of 25ft so -1 looks like a placeholder that something (perhaps a system between our APIs and the data you have) has inserted to represent a missing altitude.

(more generally, altitudes are typically given as pressure altitudes or as altitude AMSL; they are not altitudes above ground level, so 0 is not necessarily ground level)


Straight from the mouth of the FlightAware Staff! I was leaning toward an error on our end or with an API. This has been very helpful. Thank you!