I enjoyed it,
I would suggest adding the character of a jumpmaster giving commands instead of a speaker however, jumpmasters are trained to inspect paratroopers for safety and give commands in coordination with the crew chief and pilot of the aircraft. Jumpmasters have a specific set of commands they call out before jumping, you can find them if you wish, try Fort Benning's website perhaps, the US Army's Airborne School is there, and I'm sure you can find a ton of great information if you want to add some nice details to flesh your story out a bit.

Hope you continue too!