Delta Airlines has canceled hundreds of flights during Thanksgiving due to staff shortages during the busiest travel week since the launch of the Corona virus pandemic.

Demand is less than half of last year’s level as the Pandemic Transportation Security Administration airport screenings rose more than a million on Sunday and Wednesday.

On Thursday, Delta canceled about 300 flights, about 20% of the schedule and about 160 flights, or 9% of the Friday schedule.

Many factors have put pressure on our ability to staff dozens of scheduled flights on time, ”Delta said in a statement. “We apologize to our customers for any inconvenience caused by these flight cancellations.”

The airline expects operations to return to normal over the weekend, and most of the customers who canceled their flights were re-booked on the same day.

Hundreds of pilots have already taken retirement packages after seeing the performance issues reported from the Wing blog. Earlier this week The pilots agreed to accept the partial paDo not fly until 2022, avoiding more than 1,700 furrows.

Injuries to pilot ranks can cause cascading problems as pilots need to be trained and retain currency on some aircraft so they cannot easily switch from one to another.