The U.S. Federal Aviation Administration (FAA) said it gave clearance to an estimated 45% of the U.S. commercial airplane fleet to perform low visibility landings at some airports where 5G C-band will be deployed. The FAA has previously warned airlines that potential 5G interference could affect airplane instruments such as altimeters and affect low visibility operations.

U.S. passenger and cargo airlines have warned the officials that the issue could severely impact flights. The trade group Airlines for America, which represents passenger and cargo airlines, said even with the FAA’s approval the airlines would not be able to operate the majority of passenger and cargo flights because of the agency’s 5G related restrictions. The group added that new action is needed before the planned January 18 rollout.

The FAA cleared two radio altimeter models used in many Boeing and Airbus planes, just days before AT&T and Verizon announced new 5G service on Wednesday. The FAA said it expects to give new approvals in the coming days.

The FAA said approvals open runways at 48 of 88 airports most affected by 5G C-band interference. However, the agency warned that even with the approvals, flights at some airports may still be affected.

AT&T and Verizon, which won almost all of the C-Band spectrum in an $80 billion auction last year, agreed to buffer zones around 50 airports to reduce interference risks. The FAA revealed 50 U.S. airports that will have 5G buffer zones including New York City, Los Angeles and Chicago among others.