Legal Interpretations
Unterseher-World Airways 2010
Summary
The Question
To dispatch an extended overwater flight under 14 CFR 121.615(a), must both the destination and the required alternate be forecast at or above minimums at the estimated arrival time?
Background
A World Airways captain wrote that the airline reads 14 CFR 121.615(a) to require only the destination or the required alternate to be forecast above applicable minimums at the estimated time of arrival, and asked whether both must be.
The FAA’s Interpretation
No. Under 14 CFR 121.615(a), the destination may be below minimums at dispatch so long as the alternate is at or above minimums at the estimated time of arrival. But a flight may not be dispatched if the alternate would be below minimums on arrival there (14 CFR 121.625). If the alternate falls below minimums en route, the release may be amended under 14 CFR 121.631(f).
- Requester
- Unterseher
- Organization
- World Airways
- Issued
- April 12, 2010
- Subject
- Air Carrier & Commercial Operations
Regulations Cited
Page 1
U.S. Deportment
of Transportation
Federal Aviation
Administration
APR 1 2 2010
Office of the Chief Counsel
Captain Gregory Unterseher
World Airways EXCO
8595 SE McBreen Lane
Port Orchard, WA 98367
Dear Capt. Unterseher,
800 Independence Ave., S.W.
Washington, D.C. 20591
This is in response to your request for a legal interpretation submitted on December 9, 2009, regarding the alternate weather minimum requirements under 14 C.F.R. § 121.615(a). Specifically, you state that World Airways interprets§ 121.615(a) to require only "the destination or the required alternate weather to be forecast to be above the applicable minimums at the [estimated time of arrival]." You question whether the weather forecasts for both the destination and the required alternate airport must be above the applicable minimums at the estimated time of arrival.
14 C.F.R. § 121.615(a) states that "[n]o person may dispatch or release an aircraft for a flight that involves extended overwater operation unless appropriate weather reports or forecasts or any combination thereof, indicate that the weather conditions will be at or above the authorized minimums at the estimated time of arrival at any airport to which dispatched or released or to any required alternate airport."
As stated in a recent interpretation regarding this issue, " [a]n air carrier may dispatch an extended overwater flight to a destination airport that is forecasted to be below minimums as long as the alternate airport is forecasted to be at or above minimums." Legal Interpretation to Captain Mark Anderson, from Rebecca MacPherson, Assistant Chief Counsel for Regulations (May 31, 2006). This is necessary to allow flexibility yet ensure proper planning in case weather conditions change during flight. Accordingly, under§ 121.615(a), at the time of dispatch, the destination airport may be below minimums so long as the alternate airport is at or above minimums at the estimated time of arrival. However, an aircraft may not be dispatched if, at the time of dispatch, the alternate airport would be below minimums at the time of arrival at the alternate airport. See 14 C.F.R. § 121.625. If conditions at the alternate airport fall below minimums while the aircraft is enroute, the dispatch or flight release may be amended in accordance with § 121.631 (f). See Legal Interpretation to Captain Mark Anderson.
Page 2
We appreciate your patience and trust that the above responds to your concerns. ff you require further assistance, please contact my staff at (202) 267-3073. This response was prepared by David Pardo, attorney for the Operations Law Branch of the Regulations Division of the Office of the Chief Counsel, and coordinated with the Air Transportation Division of Flight Standards Service.
Sincerely, /JW-.J £t: [,L,..
fo,.... Rebecca B. MacPherson
Assistance Chief Counsel for Regulations, AGC-200
Enclosure
Regulations Referenced
Snapshot retrieved August 6, 2026.