Which factor affects a pilot's ability to complete their trip under the 14-hour discretion rule?

The start time of a pilot's RAP (Rest and Activity Period) is crucial in determining their ability to complete a trip under the 14-hour discretion rule. This is because the 14-hour rule allows pilots to extend their flight duty period in specific circumstances, but it is contingent upon several factors, including their rest period prior to the flight.

The start time of the RAP directly influences when a pilot is considered to have their rest period end and their duty period begin. If the RAP starts later in the day, the pilot may be more fatigued by the time they reach the end of their duty period, potentially affecting their ability to operate safely during those final flight hours. Conversely, if a pilot's RAP starts earlier, they may feel more rested and capable of completing the trip within the time limits set by regulations.

Thus, the timing of their rest period is pivotal in assessing fatigue and ensuring safety during flight operations, making it a significant factor in their ability to complete their trip under the discretion rule.