AIM ¶ 5-2-4 — IFR Taxi Clearance
AIM 5-2-4 explains IFR taxi clearance procedures: contact ground or clearance delivery before engine start for engine start time and taxi info.
AIM 5-2-4 addresses how IFR pilots should obtain taxi clearance before departure. The recommended practice is straightforward: before you start your engines, contact the control tower on the appropriate ground control or clearance delivery frequency.
Doing this before engine start lets ATC provide you with:
- Engine start time (useful when there are flow control or wheels-up time restrictions)
- Taxi instructions
- IFR clearance information
Why it matters operationally: Calling before engine start saves fuel, reduces ramp congestion, and avoids running engines while you wait on a delayed clearance or release. At busier IFR airports, controllers may issue a Expect Departure Clearance Time (EDCT) or hold you for traffic flow management — knowing that before you spool up keeps your operation efficient and professional.
Note that this paragraph is informational guidance, not a regulatory mandate, but it reflects standard practice expected by ATC and DPEs.