What does "per diem" refer to for a crew member?

"Per diem" refers to compensation provided to crew members to cover daily expenses incurred while they are away from their base of operation. This typically includes costs such as meals, lodging, and other necessary expenses while traveling. In flight crews, per diem is essential because they often work flights that take them away from their home base, where their regular living expenses are accounted for differently.

The other options describe various forms of compensation related to flight crew work, but they do not relate specifically to the additional costs a crew member faces when traveling. Bonus pay for overtime work pertains to extra hours worked beyond standard schedules, flat rate pay for ticket sales relates to commissions or incentives linked to sales performance, and salaries paid during training focus on earnings during the training period rather than expenses incurred while away from base. Thus, the definition of per diem as money paid for time away from base is clear and aligns with standard industry practices.