Alaska Airlines requested a ground stop for its entire fleet of planes that operate under its brand name, the Federal Aviation Administration said in an advisory on Sunday night.

The reason for the advisory, issued just after 9 p.m. on Sunday, was not immediately clear. The grounding affects more than 200 planes under the Alaska Airlines brand but does not affect aircraft operated by the airline’s subsidiaries. As of April 24, Alaska Airlines said it operated 238 planes, all Boeings, under its brand.

Neither Alaska Airlines nor the F.A.A responded immediately to requests for comment.

This is a developing story.