Flying is awful, complaints show. Here's how to make it less so for holiday travel.

The volume of customer complaints against U.S. airlines is so high this year that the Department of Transportation reportedly cannot keep up with them for the first time ever.

Airline records related to flight delays and cancellations, lost luggage and damaged wheelchairs — the most common consumer qualms — have worsened since last year, an analysis of federal flight operations data by the U.S. Public Interest Group (PIRG) shows.

"It's not your imagination, air travel has become much more stressful. We have new fees, more cancellations, delays, long TSA lines and lost bags," Teresa Murray of the PIRG told CBS MoneyWatch.