Final answer:
Flight crew members on reserve are typically required by airlines to report for duty within a short notice period, for which they must always be prepared unless excused for valid reasons. This adherence to timely reporting is part of the professional expectations inherent in the airline industry.
Step-by-step explanation:
The question you asked pertains to the requirements for flight crew members who are on reserve to show up on time for duty. Although the specific time frame within which a reserve flight crew member must report for duty can vary by airline, it is typical for the airline industry to expect on-call crew members to be available and able to report within a few hours' notice. This is part of the overarching expectations of airline personnel to show up to work and be prepared for their designated shifts unless they have an approved reason for absence, adhering to company protocols for reporting any needed time off.
In comparison to other industries or scenarios, such as the military where troops can be sent to foreign countries and must receive congressional confirmation within 48 hours, airline employees also have to navigate through their own set of strict time-bound regulations, including the requirement for passengers to submit documentation for service animals 48 hours before travel in some cases.