Flying five by five: our solution to 5G aircraft interference

Technology is a marvellous thing, but the pace of change can lead to unforeseen challenges. Take 5G deployment. This technology gives mobile device users a massive boost of bandwidth, enabling fibre-like speeds on the go. Yet its introduction in the US almost grounded the civil aviation industry.

It transpired that 5G signals from phone towers close to airfields could interfere with avionic equipment on a lot of airliners – in particular the radio altimeters or radar altimeters that airline pilots depend on to give an accurate altitude reading in reduced visibility. And accurate altitudes are pretty important when it comes to landing aircraft. 

While the avionics equipment was certified to operate with 5G signals that are beamed from satellites, it wasn’t certified to work alongside the new ground-based 5G towers, which transmit a concentrated signal across a shorter distance. This was a particular issue for mobile phone masts erected close to airports. When telecoms providers like Verizon and AT&T scheduled the big potential 5G C-Band wireless switch-on for January 19, 2022, unless the towers by the airport were deactivated, these power levels would have caused havoc to aviation safety. 

The chief executives of the major US airlines warned that the vast majority of aircraft would essentially be grounded. United predicted delays and cancellations of 15,000 flights a day, and many foreign airlines were starting to pre-emptively take flights off the schedule. 

For Cathay Pacific, transpacific routes are among the busiest long-haul routes for our passenger and freighter aircraft. “All of our aircraft are affected to some degree, dependent on how 5G service is implemented at different destinations and the restrictions applied to the aircraft type by the manufacturer,” wrote Captain Mark Hoey, who is also our General Manager Operations, at the time.

All of our aircraft that fly US routes – the Boeing 777, the 747 freighters and the Airbus A350 – could have been affected. Aircraft have a first lifespan of around 20 years, so aircraft approaching that age were designed and built when even 4G was a distant dream. By comparison, the telecoms industry moves at the speed of – well, 5G – and it needed a return on its enormous investment in its new infrastructure.  

Thankfully, the 5G switch-on close to airports was suspended, but it left us just six months to design, develop, implement and fit the aircraft to keep them flying. Teams from Engineering, Flight Operations, Procurement and Aircraft Trading got together and started work immediately, as they knew demand for these solutions was going to be competitively intense in that tight time window.  

“During that time, we needed to research the solution, source the parts and perform the modifications,” says Richard Xing, Head of Technical Services, Engineering.  “And there was Christmas in the middle – a peak holiday period with the potential to put the brakes on logistics and delivery times.” 

Undeterred, the teams got to work. One collected data and insights on what would be needed to make each aircraft type compliant. Another scoured the globe for these sought-after parts; another secured cost-effective contracts with manufacturers. That left Engineering to carry out the large-scale fit-out of all the aircraft required to keep flying to the US, completed a month before schedule and the deadline. 

We became the first airline outside the US to receive a certification to fly there. An impressive effort that netted the project team a coveted Niki Award, the highest internal commendation for excellent work behind the scenes. Now you know that the next time you’re on an aircraft in the United States and switch off airplane mode – it took six months of hard work to make it possible for aviation and 5G C-band environments to safely coexist.