Don't forget that if you don't wipe the stick it will read far higher than it actually has.
I used to from memory always keep the van at about 8 quarts else it blew it out the back, even if the total oil was 12 quarts.
Usually in the tropics these engines will burn about half a litre an hour so a bungle run should use about a quart of oil.
Good job to get it on the ground, poor airmanship having to. I bet he checks it very thoroughly from now on in his next job. Many a guy I know over the years has been sacked from the gator. For most it's not the end of the world and they move on to bigger and better things.