Staff standby on duty?
I see that it makes perfect sense for staff traveling on leisure to get standby tickets - filling an empty seat costs roughly the additional fuel spent, and staff are the people who know the rules well and make little trouble, so it makes sense to reward them with cheap standby tickets.
But why on duty travel? Logically, the staff on duty should get confirmed seats and bump paying passengers if necessary... after all, the question is either bump one passenger to get space for a pilot or mechanic, or ground a whole plane they are travelling to get off the ground.