<p>Airlines in the United States canceled about 1,400 flights on Friday after a massive winter storm knocked out power and affected businesses in 12 states, with forecast for a brutal freeze over the weekend.</p>.<p>A total of 1,395 flights were canceled and 788 flights were delayed as of 8.16 am ET, according to flight-tracking website FlightAware.</p>.<p>"We expect some operational challenges due to the weather in the Midwest today and potentially tomorrow due to the winter weather in the region," Delta Air Lines said.</p>.Iran says US-Britain attack on Houthis will fuel instability in region.<p>Southwest Airlines issued a travel advisory and said some of its flights in regions such as Chicago, Detroit and Omaha could be impacted.</p>.<p>The Federal Aviation Administration had on Thursday warned that clouds, snow and windforce could delay flights at certain airports.</p>.<p>Southwest led the list of cancellations with 270 flights followed by United Airlines Holdings at 252.</p>.<p>United also canceled some flights through Saturday as it awaits regulatory approvals to resume operating Boeing's 737 MAX 9 jets in the country.</p>.<p>The carrier said it was working to return its MAX 9 jets to service and was continuing to operate some planned flights by switching to other aircraft types.</p>.<p>The FAA had on Thursday launched a formal investigation on 737 MAX 9 after a cabin panel blew off an Alaska Airlines flight last week in mid-air, forcing an emergency landing.</p>
<p>Airlines in the United States canceled about 1,400 flights on Friday after a massive winter storm knocked out power and affected businesses in 12 states, with forecast for a brutal freeze over the weekend.</p>.<p>A total of 1,395 flights were canceled and 788 flights were delayed as of 8.16 am ET, according to flight-tracking website FlightAware.</p>.<p>"We expect some operational challenges due to the weather in the Midwest today and potentially tomorrow due to the winter weather in the region," Delta Air Lines said.</p>.Iran says US-Britain attack on Houthis will fuel instability in region.<p>Southwest Airlines issued a travel advisory and said some of its flights in regions such as Chicago, Detroit and Omaha could be impacted.</p>.<p>The Federal Aviation Administration had on Thursday warned that clouds, snow and windforce could delay flights at certain airports.</p>.<p>Southwest led the list of cancellations with 270 flights followed by United Airlines Holdings at 252.</p>.<p>United also canceled some flights through Saturday as it awaits regulatory approvals to resume operating Boeing's 737 MAX 9 jets in the country.</p>.<p>The carrier said it was working to return its MAX 9 jets to service and was continuing to operate some planned flights by switching to other aircraft types.</p>.<p>The FAA had on Thursday launched a formal investigation on 737 MAX 9 after a cabin panel blew off an Alaska Airlines flight last week in mid-air, forcing an emergency landing.</p>