United Airlines is canceling 35 round-trip flights from its Newark Airport schedule per day starting this weekend amid continued air traffic control staffing issues and construction on one of the runways.

United Airlines CEO Scott Kirby says more than 20% of Newark's air traffic controllers "walked off the job" this week, forcing the airline to indefinitely remove nearly three dozen round-trip flights from its Newark schedule per day.

"It's disappointing to make further cuts to an already reduced schedule at Newark, but since there is no way to resolve the near-term structural FAA staffing issues, we feel like there is no other choice in order to protect our customers," Kirby said in a letter.

It comes after several days of travel nightmares -- and experts warn it's only going to get worse as the summer travel season heats up.

By Friday afternoon, 19 flights were canceled and 297 experienced delays.