Major US carrier Delta Air Lines has cancelled approximately 100 flights owing to staff shortage, and as a result opened up some middle seats a month earlier than planned for passengers as pandemic travel increases.

During the past few days, the carrier recorded more than one million passengers, which is the highest since before the Covid-19 pandemic began in 2020.

Delta Air Lines spokeswoman was quoted by Bloomberg as saying: “Delta teams have been working through various factors, including staffing, large numbers of employee vaccinations, and pilots returning to active status.

“We apologise to our customers for the inconvenience and the majority have been rebooked for the same travel day.”

To accommodate passengers, Delta took various measures to scale up passenger capacity, including opening middle seats just for Sunday and Monday.

In April last year, the carrier closed booking of middle seats to maintain social distancing but decided to scrap the decision starting May this year as air travel recovers and more people have received Covid-19 vaccinations.

Last week, the Centers for Disease Control and Prevention announced that vaccinated persons need not go through a Covid-19 test and quarantine when traveling within the US.

Recently, American Airlines and United Airlines stated that they are now operating at 80% full capacity.

Delta cut approximately 17,000 workers on voluntarily basis, while another 40,000 took unpaid leave as it implemented cost reduction measures amid the pandemic. The company reported a loss of $12.4bn last year.