"their" own
“their” own
In this case “their” is appropriate because the sex of the skydiver is unknown. You could use the more awkward “his/her own” or “his or her own.” I tend to prefer the “his or her own” grammar, myself, but lots of people think that is caving in to the feminists.
Of course, not long ago, “his” in this usage would have been understood to be gender-neutral.
Never let it be said English is simple, especially when liberals are ruining it left and right.
Just wait until “homo sapien with vagina and ovaries” overtakes “woman” in general usage.
The dead person deserves a real pronoun, not “their.”