The furloughs will include around 10,000 flight attendants and 2,500 pilots, according to the memo from CEO Doug Parker and President Robert Isom on Wednesday.

"We hope to reduce the actual number of furloughs significantly through enhanced leave and early-out programs for represented workgroups, which we are announcing today," it added.

Earlier this month, United Airlines warned nearly half of its frontline workforce that they could be furloughed this fall.

The airline said 36,000 workers will receive layoff notices.