IFR Alternate Requirements
The 1-2-3 Rule
For an IFR flight, you do not have to file an alternative if the following conditions are forecast at ETA +/- 1 hour:
- At least 2000 ft ceiling
- At least 3 SM visibility
Alternate Minimums
In order to qualify as an alternate, an airport must be forecast to have at least:
- 600 ft ceiling and 2 SM visibility for precision approaches
- 800 ft ceiling and 2 SM visibility for non-precision approaches
If the airport has non-standard alternate minimums defined for it (identified by an “A” icon in the notes section of their FAA approach plates)), those values apply instead. These non-standard minima are published in the U.S. Terminal Procedures Publication (TPP).