Plain English Meaning

These are special weather rules for taking off on an instrument flight plan from certain airports, where you need clearer weather than usual before you are allowed to depart. The airport has something nearby — like hills, towers, or terrain — that makes a normal departure unsafe in low visibility, so the FAA raises the bar.

Full Definition

Takeoff weather minimums (visibility and sometimes ceiling) that are higher than, or otherwise different from, the standard minimums established by regulation for an IFR departure at a particular airport. They are published when terrain, obstacles, or other local factors require better visibility or to depart safely. Nonstandard are indicated on by a small symbol containing the letter T and are detailed in the of the .