Skydiving uploads: Workout category and preserving airborne altitude

Hi everyone,

I'm Anubhav, the developer of BreakOff, a skydiving logbook and analysis app for iPhone and Apple Watch that also imports Garmin FIT recordings. Strava Developer Support pointed me here for guidance on a proposed upload integration.

We want jumpers to share the actual jump, from reviewed exit to touchdown, with GPS, altitude and heart rate where recorded. The aircraft climb and time on the ground would be excluded.

We've run a manual file-upload experiment using a real Garmin recording. GPX and TCX exports containing GPS altitude appeared to show a terrain-level elevation profile rather than the airborne descent. A later GPX using pressure-derived altitude and a creator string containing "with barometer" displayed an airborne profile alongside the route and heart-rate graph.

That later test changed both the altitude source and creator metadata, so it does not isolate which change affected Strava's processing. The pressure conversion used a standard atmosphere, and the unfiltered diagnostic contained spikes; we aren't treating the result as proof of altitude accuracy or exact sample preservation. These were manual uploads, not an end-to-end API validation.

I'd appreciate guidance on three points:

1. Is Workout an appropriate interim activity type for explicitly labelled skydives, given the absence of a Skydiving category?

2. What is the supported way for an app-generated upload to identify recorded barometric altitude and preserve an airborne descent? In particular, is the "with barometer" creator convention appropriate here, and when would Strava apply terrain correction or filtering during rapid descent?

3. Is there a recommended FIT or TCX representation for GPS, altitude and heart-rate samples that arrive at different timestamps? We want to preserve missing readings rather than fill them with zeroes or interpolated values.

The dedicated Skydiving category request is being raised separately. For this post, we're hoping to establish a reliable, supported upload approach before building out the integration.

Thanks,
Anubhav
BreakOff