All Nippon Airways Co. and Japan Airlines Co. joined major U.S. carriers Tuesday in warning that the impending start of new 5G mobile phone services around U.S. airports could disrupt their flights operated with the Boeing 777 aircraft.

The planned deployment of the telecommunication services on Wednesday is widely feared to affect planes' navigation systems.

ANA said it might cancel up to 20 U.S. passenger and cargo flights to and from Haneda and Narita airports in Japan through Thursday, while JAL decided to cancel three passenger and five cargo flights on Wednesday.

According to ANA, its plan is to switch to the Boeing 787 or other planes for flights using the Boeing 777, but an inability to cover all such flights with substitutes could affect up to around 650 passengers.

Both ANA and JAL said the navigation concern does not affect their operations at other domestic airports and that they have not received any reports of trouble during flights in Japan or Europe where 5G services have already launched.

American aerospace giant Boeing Co. has informed airlines that 5G will potentially interfere with sensitive aircraft equipment such as radio altitude meters.

The Boeing 777 is widely used by many airlines including on long-distance routes such as those connecting Asia and North America.

The U.S. Federal Aviation Administration and the U.S. airline industry have long called for delaying the launch of 5G service due to safety concerns.