CA.I.D.K3bFAA-S-ACS-7B · Nov 2023Knowledge
b. Estimated time of arrival, including conversion to universal coordinated time (UTC)
Calculating: b. Estimated time of arrival, including conversion to universal coordinated time (UTC)
Bottom line
FAA uses Coordinated Universal Time (UTC) for all operations, and the term "Zulu" may be used to denote UTC. An estimated time of arrival is calculated from the filed or amended (with ATC) estimated time en route. To convert Eastern Standard Time to Coordinated Universal Time, add 5 hours.
Key numbers
| Number | What it means |
|---|---|
| Add 5 hours | EST to UTC |
| Add 6 hours | CST to UTC |
| Add 7 hours | MST to UTC |
| Add 8 hours | PST to UTC |
| Subtract 1 hour | Daylight time |
FAA references
- AIM 4-2-12 (Time) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
- 14 CFR 91.185 (IFR operations: Two-way radio communications failure.) — eCFR current as of 2026-03-05
- AIM 7-3-2 (Pre-Flight Planning for Cold Temperature Altimeter Errors) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
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