July 20 (Reuters) - Alaska Airlines has

requested for a ground stop for all its mainline aircraft, the

U.S. Federal Aviation Administration (FAA) status page showed on

Sunday.

The company also requested for ground stops of all Horizon

Air ( ALK ) flights, the regional subsidiary operating Alaska Airlines

flights.

The reason behind either of the requests was not immediately

clear.

Alaska Airlines, Horizon Air ( ALK ) and the FAA did not immediately

respond to Reuters' requests for comment outside regular

business hours.

The FAA status page showed all destinations being impacted

by the ground stop of Alaska's mainline aircraft, and Horizon's

ground stop.

Alaska Air Group ( ALK ) maintains an operational fleet of 238

Boeing 737 aircraft, and 87 Embraer 175 aircraft, according to

its website.

In June, Alaska Air Group ( ALK )-owned Hawaiian Airlines said some

of its IT systems were disrupted by a hack. Alaska Air Group ( ALK )

said it was still determining the financial impact of the hack.