The problem with abbreviations, especially within a jargon, is the multiple uses of a single abbreviation.
FTE = failure to eject or failure to extract, same problem to the shooter at he moment, but really quite different problems with different fixes.
BTT = bump to top or back to top ... differences with out much distinction.
Don't use them if there is ambiguity in their use.
Try not to use them at all. Then there is no problem with the reader understanding what they mean.
"The irony of the Information Age is that it has given new respectability to uninformed opinion." - John Lawton, speaking to the American Association of Broadcast Journalists in 1995