IFR alternate required?
Reads the destination forecast for the 1-2-3 rule (alternate required if below 2,000 ft / 3 SM from 1 hr before to 1 hr after ETA), then finds qualifying alternates for your equipment.
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Filing an alternate is more than picking the next airport over
The 1-2-3 rule tells you whether you need an alternate. Choosing a legal one is the part that trips pilots up: the alternate needs an instrument approach you're equipped to fly, weather that's being reported, and forecast conditions that meet the alternate minimums. A GPS-only airport doesn't count for a non-WAAS aircraft. This tool checks the destination TAF for the ±1 hr window, then lists nearby airports that actually qualify for your equipment.
How it decides
It parses the live destination TAF, finds the periods covering your ETA window, and flags an alternate as required if the forecast ceiling drops below 2,000 ft or visibility below 3 SM. The candidate list is filtered to airports with a published approach and a reporting weather station — and, for non-WAAS, to those with a ground-based approach.
Always confirm on the plate
Standard alternate minimums are 600-2 (precision) and 800-2 (nonprecision), but many airports publish higher, non-standard minimums (the ⊠ symbol) or are "NA" as an alternate. Verify the approach plate and current NOTAMs before you file.
The calculator is just the start
These same calculations power the SkyReady app — alongside an offline-first logbook, automatic FAA currency, proficiency scoring, and a one-tap Go/No-Go readiness brief. Free to log.