British Airways is among the airlines cancelling US flights due to 5G safety concerns.
The action is in response to fears that the activation of the C-band strand of the mobile phone service near US airports on Wednesday could disrupt planes’ navigation systems.
Boeing 777s are thought to be particularly at risk of being affected.
The introduction of the technology has been halted in some parts of the US but is going ahead elsewhere.
The UK’s Civil Aviation Authority (CAA) said it has “issued safety advice” to airlines.
British Airways cancelled a handful of flights from Heathrow to Boston, Chicago, Los Angeles, New York, and San Francisco on Wednesday.
The airline said in a statement: “Safety is always our priority and although we had to cancel a handful of services, we’ve done everything we can to minimise inconvenience for our customers.
“We’ve changed the aircraft operating some of our flights and rebooked those on cancelled services onto alternatives.
“We’re disappointed that, like other airlines, some of our customers’ travel plans have been disrupted.”
Customers whose flights have been cancelled are being offered a full refund or the option to rebook.
Some flights due to be operated by Boeing 777s are using different, larger aircraft such as the Airbus A380 to ensure people can still fly on the same day.
Other airlines have made many more cancellations.
Emirates suspended all its flights to nine US airports on Wednesday “until further notice”.
The Dubai-based carrier told customers the measure was “due to operational concerns associated with the planned deployment of 5G mobile network services in the US at certain airports”.
It added: “Emirates regrets any inconvenience caused. We are working closely with aircraft manufacturers and the relevant authorities to alleviate operational concerns, and we hope to resume our US services as soon as possible.”
Other airlines to cancel flights include Air India Japan-based ANA, Japan Airlines and Korean Air.
