Popular US aircraft operator Alaska Airlines implemented a fleet-wide grounding order for aircraft operating under its primary brand, according to a Federal Aviation Administration notice issued Sunday evening.The FAA’s advisory, released shortly after 9 pm Sunday, came without immediate explanation. The directive impacts over 200 aircraft flying under the Alaska Airlines banner, while excluding planes operated by its subsidiary companies.The Alaska Air Group also requested ground stops for all Horizon Air flights, the regional subsidiary operating Alaska Airlines flights. The FAA status page showed that all destinations were impacted by the ground stop of Alaska’s mainline aircraft and Horizon’s operations, accordin to Reuters.Alaska Air Group maintained an operational fleet of 238 Boeing 737 aircraft and 87 Embraer 175 aircraft, according to its website.Later, the airline was quoted by ABC News saying, “At approximately 8 pm Pacific on Sunday, Alaska Airlines experienced an IT outage that’s impacting our operations. We requested a temporary, system-wide ground stop for Alaska and Horizon Air flights until the issue is resolved.” “We apologize to our guests for this inconvenience. There will be residual impacts to our operation throughout the evening. If you are traveling tonight, please check the status of your flight before leaving for the airport,” it added.