Workers rebuild a cellular tower with 5G equipment in Orem, Utah.

AT&T and Verizon on Sunday rejected the U.S. Department of Transportation’s request that they delay this week’s scheduled launch of a new round of 5G wireless service — and instead pledged to take enhanced measures to avoid warned disruptions of air travel.

“With continued COVID crises, it has never been more important that our country’s critical communications infrastructure have the spectrum needed to handle escalating traffic demands from our customers,” AT&T CEO John Stankey and Verizon CEO Hans Vestberg wrote in a joint letter to the department.