Some flights have been canceled since the new networks were turned on last month, but predictions of widespread cancellations turned out to be wrong. The Federal Aviation Administration has cleared 90% of the nation’s airline fleet to land during poor visibility at airports near 5G cell towers.

Still, at a hearing Thursday, lawmakers said the matter—a standoff between two federal agencies—should never have reached the point that the White House had to step in to get limits on 5G service near airports.

House Transportation Committee Chairman Peter DeFazio, D-Ore., blamed the Federal Communications Commission, which approved plans by Verizon and AT&T to launch faster and more reliable 5G service using the C-Band part of the radio spectrum that is close to the range used by radio altimeters. Those devices measure the height of planes above the ground and are critical for landing when visibility is limited by bad weather.

DeFazio said he and aviation interests raised concerns about possible interference as early as 2018, but the FCC ignored them and auctioned off 5G spectrum without ensuring there would be no interference with aviation.

“Having a dropped call is way less serious than having a dropped airplane,” he said.

The FCC has said it provided an adequate buffer between C-Band and radio altimeters to prevent interference.

FAA Administrator Stephen Dickson detailed the agency’s attempts to raise concerns with the FCC. He said analysis of new information from the wireless companies has allowed his agency to clear more planes, but that concerns haven’t been eliminated for all altimeters.

The FCC and the telecom companies say that 40 other countries have rolled out C-Band 5G service without any reports of radio interference with planes. Aviation groups counter that most of those countries have lower-power 5G signals than the U.S or imposed other restrictions on the service to prevent interference.

Verizon and AT&T agreed to two delays before launching most of their planned new 5G service on Jan. 19 except near airports, where they agreed not to turn on new cell towers for the time being.

Dozens of flights were canceled last month because of 5G concerns, but widespread cancellations were avoided.

The committee was scheduled to hear from several representatives of the airline industry, and the president of a telecommunications trade group. The wireless industry official said aviation concerns were based on a 2020 study that she said was flawed.

FCC Chairwoman Jessica Rosenworcel was invited but had a conflict, according to the committee.