Void Times & Takeoff Minimums
What a clearance void time obliges you to do at a non-towered field, and the takeoff minimums that apply before you ever get there.
Clearance Void Times (Non-Towered)
At airports without a control tower, clearances often include a void time — if you're not airborne by that time, the clearance is void.
- If you can't depart by the void time, advise ATC ASAP of intentions
- If you don't contact ATC within 30 minutes after the void time, you're considered overdue and search and rescue is initiated
- Other IFR traffic into that airport is suspended until you contact ATC, the 30-minute window expires, or 30 minutes after release time if no void time was issued
- If you depart at or after the void time, you have no IFR separation and are in violation of 14 CFR § 91.173
- If you choose to depart VFR after the void time expires, do not use the previously assigned IFR squawk code
Standard phraseology: "Clearance void if not off by [time]; if not off by [time] advise [facility] not later than [time] of intentions."
IFR Takeoff Minimums
- Part 91 operators: No standard takeoff minimums. Legally, zero-zero is permitted — though "legal" and "smart" diverge here.
- Part 121/135 (commercial) — 1 or 2 engines: 1 SM visibility
- Part 121/135 — 3+ engines: 1/2 SM visibility
- Part 121/135 — Helicopters: 1/2 SM visibility
The "Troubled T" symbol (a black triangle with "T" inside) on the approach plate means takeoff minimums, diverse vector area information, or obstacle departure procedures are published in a separate document. Look it up before departing in IMC — there's terrain or obstacles dictating non-standard requirements.