By Kannaki Deka
(Reuters) -U.S carriers Delta Air Lines and Alaska Air Group cancelled hundreds of flights on Tuesday due to adverse weather conditions and rising cases of the Omicron variant.
Delta said it expected to cancel more than 250 of 4,133 scheduled flights on Tuesday, while Alaska cancelled 170 flights across its network and warned of more cancellations and delays throughout the week.
Total cancellations as of 14.00 ET (19.00 GMT) within, into, or out of the United States stood at 1,034, with 2,694 flights delayed, marking a fifth day of flight cancellations.
Delta said it was working to re-route and substitute some planes.
Alaska Airlines said as it heads into Wednesday and Thursday, it is proactively thinning Seattle departures by about 20% to allow for additional time to de-ice aircraft, a requirement during winter weather.
Despite the ongoing disruption, the U.S. Centers for Disease Control and Prevention said on Tuesday it is not currently considering recommending a vaccine mandate for domestic flights, responding to a suggestion the previous day by Dr. Anthony Fauci, the government's top infectious disease expert.
"Right now, what we're talking about is ways to get people vaccinated. Certainly domestic flights has been a topic of conversation, but that is not something we're revisiting right now," CDC Director Rochelle Walensky said on National Public Radio when asked about Fauci's comment.
Walensky said the CDC considers all potential policy and it strongly recommends vaccinations, noting that unvaccinated people have a much higher chance of being hospitalized from COVID-19.
U.S. carriers also canceled more than 1,000 flights on Monday after grounding thousands of planes over the Christmas holiday weekend as airlines struggled with staff shortages from COVID-19 infections and bad weather in parts of the country.
Snowy weather in the Pacific Northwest on Monday contributed to the cancellation of more than 110 flights scheduled to land at Seattle-Tacoma Airport.
Rising infections causing pilots and cabin crew to quarantine have also forced many flight cancellations.
The average number of new COVID-19 cases in the United States has risen 55% to over 205,000 per day over the last seven days, according to a Reuters tally.
The CDC said on Monday it was shortening the recommended isolation time for infected Americans to five days from 10 days previously, if they are asymptomatic. The move could help airlines and other businesses mitigate staff shortages.
(Reporting by Kannaki Deka in Bengaluru; Additional reporting by Chris Gallagher in Washington and Rhea Binoy in Bengaluru; Editing by Shinjini Ganguli and Richard Pullin)