United Airlines says several Christmas Day flights were cancelled because of staffing issues. They say the cancellations were not because of the weather.

United cancelled about 50 flights on Tuesday, which was about 14 percent of its scheduled departures from Denver.

A spokesman says pilots were working too many hours because of the storms in the Midwest United States. That caused a ripple effect at DIA.

"We proactively cancelled a small percentage of flights to better accommodate our customers and get them to their destinations safely and as quickly as possible. We have had some residual impact on our operations as a result of this weekends storms," said spokesperson Jeff Kovick.

Airline spokeswoman Robin Urbanski says Tuesday was a light travel day so the airline is using it to move planes and crews to the airports where they need to be to carry holiday travelers home. She says flights aren't crowded today so passengers on canceled flights have been moved to other ones.

United says it is problems that the staff issues could create more problems through the rest of the week.<sic, must admonish 9news on its grammar>