WASHINGTON — U.S. Transportation Secretary urges airlines to proactively adjust schedules amid 5G altimeter retrofit concerns.

In a communication to Airlines for America (A4A) on Friday, U.S. Transportation Secretary Pete Buttigieg cautioned about potential flight disruptions commencing July 1 due to a notable portion of airplanes not yet equipped with updated radio altimeters that mitigate 5G C-Band interference. He strongly advised airlines to amend their schedules proactively to evade undue inconvenience.

Although over 80% of the nation's domestic fleet serving U.S. airports has been retrofitted, a considerable quantity of aircraft, inclusive of many operated by foreign airlines, still await this necessary adaptation. This lack of readiness could particularly amplify delays and cancellations on adverse-weather days when visibility is reduced, according to Buttigieg.

The 5G service's potential to interfere with airplane altimeters, integral to ascertaining an aircraft's elevation from the ground especially during challenging weather landings, instigated temporary disruptions at a few U.S. airports last year. This was due to cancellations of some flights by international carriers fearing this very interference.

Representing major U.S. carriers, A4A assured that the airlines are committed to updating the altimeters. However, the persisting lag in global supply chains relative to the current demand is a hindrance. A4A's member carriers remain optimistic about their ability to uphold their flight schedules' integrity, notwithstanding the looming deadline.

International airlines have repeatedly expressed concerns about this fast-approaching deadline. In 2022, AT&T and Verizon voluntarily consented to postpone some C-Band 5G utilization until July to provide airlines a window for the necessary radio altimeter retrofit.

The Transportation Secretary insisted on airlines possessing non-upgraded equipment to judiciously recalibrate their schedules in consideration of the number of aircraft still requiring retrofitting, thus averting potential customer inconvenience based on unrealistic published schedules.

Delta Air Lines informed on Friday that it had been notified by its supplier of an insufficiency in radio altimeters for its entire fleet by July 1. Approximately 190 of Delta's narrowbody aircraft, encompassing all A220s, most A319s and A320s, and a few A321s, are still without updated radio altimeters. However, Delta assured that all its widebody aircraft will have the upgraded equipment prior to the deadline.

In a bid to address aviation safety apprehensions, major U.S. GSM operators, including AT&T, Verizon, T-Mobile US, and US Cellular, consented to several voluntary measures. Following protracted discussions with the Federal Aviation Administration (FAA), this agreement will facilitate wireless carriers to augment power levels to achieve full C-Band usage on July 1.

Buttigieg emphasized on Friday that the passengers should not suffer due to any airline's inadequacy to sufficiently equip their aircraft to operate safely within the 5G C-band ecosystem.