By David Shepardson

WASHINGTON (Reuters) -The Federal Aviation Administration (FAA) began publishing notices early on Thursday that detailed the extent of potential impact of new 5G wireless service on sensitive aircraft electronics.

The FAA has been in talks with airplane makers, airlines and wireless carriers to reduce the impact of new wireless service set to begin on Jan. 19.

The FAA has warned that potential interference could affect sensitive airplane instruments like altimeters but on Wednesday reported progress.

AT&T and Verizon Communications, which won nearly all of the C-Band spectrum in an $80-billion auction last year, on Jan. 3 agreed to buffer zones around 50 airports to reduce the risk of interference. They also agreed to delaydeployment for two weeks, averting an aviation safety standoff.

The FAA began publishing what are known as 'Notices to Air Missions' at midnight Thursday local time offering details on "aircraft with untested altimeters or that need retrofitting or replacement will be unable to perform low-visibility landings where 5G is deployed."

More than 300 notices had been posted by 01:00 ET, including many around major airports and hospitals where medical helicopters are used. The FAA did not respond to a question about how many in total were to be published.

Many of the notices https://notams.aim.faa.gov/notamSearch/nsapp.html#/details say certain procedures are unavailable unless the FAA approves alternative methods of compliance "due to 5G C-Band interference."

The wireless industry provided additional transmitter location data and the FAA said it was able to determine that in the initial 5G deployment, aircraft will be able to safely land in low-visibility conditions on some runways without restrictions.

Some notices include details of how instrument approaches at major airports are impacted. The FAA has determined that some GPS-guided approaches will continue to be possible at certain airports like Miami and Phoenix.

The FAA said Wednesday that it "expects to provide updates soon about the estimated percentage of commercial aircraft equipped with altimeters that can operate reliably and accurately in the 5G C-Band environment."

The FAA is still "working to determine which radar altimeters will be reliable and accurate with 5G C-Band deployed in the United States."

On Friday, the FAA picked 50 U.S. airports that will have buffer zones when wireless carriers turn on new 5G C-band service.

(Reporting by David Shepardson; Editing by Leslie Adler and Kenneth Maxwell)