Even at smaller facilities without a control tower, trying to multitask in the cockpit to, say, beat a clearance void
time or get to the restroom, is a distraction from the task at hand: safely and efficiently taxiing to or from the runway.
if not off in [number of] minutes (or by a specified Zulu time).
If you call, expect a void time: "Clearance void
if not off by 1030." You can depart within that period and fly the issued clearance.
There's a variation you may want to consider: a cellphone call to Flight Service or ATC requesting an instrument clearance with a takeoff time and clearance void
time--a narrow window of time during which you are permitted to enter the IFR system before establishing radio contact.
I can't abort, I've got a clearance void
time and it'll be a pain in the whatsis to sort that out if I don't pick it up."
Then she says, "Clearance void
if not off by 1830Z." She may also add, "If not off by 1830 advise Departure not later than 1900 of intentions.
The self-imposed pressures of a clearance void
time, a distant appointment or passenger expectations can mean we'll ignore or minimize the importance of ensuring the airplane is ready, even when we need to the most.
is precise: "Pilots who depart at or after their clearance void
time..." [Emphasis added!
The FAA's Aeronautical Information Manual (AIM) says a clearance void
time is "[u]sed by ATC to advise an aircraft that the departure clearance is automatically canceled if takeoff is not made prior to a specified time." Of course, there's no way ATC can know when we take off from a non-towered field.
Contact Flight Service or ATC to get your clearance with an IFR release, or with a clearance void
"If not off by 1210, advise me no later than 1215 of intentions." Again, AIM 5-2-6: "A pilot who does not depart prior to the clearance void
time must advise ATC as soon as possible of their intentions.