At London City Airport, the air traffic controllers have gone. Rising over the terminal building, the old control tower with its panoramic windows is deserted, with screens, a few pens and some hand sanitiser all that remains. City quietly switched to a remote, digital air traffic control centre earlier this year, the first major international airport to do so, and on Friday it went public with the news. The point is to improve efficiency and allow for smooth future expansion, because the same number of controllers can deal with a larger number of plane movements thanks to new technology that provides them with more data than before. Located beside former dockyards a few miles east of the Canary Wharf financial district, City is the smallest of London"s airports. Before the pandemic, it served 5 million passengers a year, mostly travelling on business to European destinations like Frankfurt and Amsterdam.Now, planes take off and land guided by air traffic controllers who are based 90 miles (144 km) away, in an office block in Swanwick, southwest of London. "Not being at the airport anymore, you don"t have that smell of jet fuel when you arrive at work," said controller Lawrie McCurrach from his new base. "But fundamentally, the job hasn"t changed. It"s still about the controller"s eyes finding the aircraft and monitoring it visually. The difference is we"re using screens instead of windows." The switch to remote air traffic control has "raised a few eyebrows", says Alison FitzGerald, London City"s chief operating officer, but she adds so far it has worked seamlessly. The controllers direct traffic using information that comes to them from a newly built, taller control tower at the airport, equipped with 16 high-definition cameras and multiple lenses. The tower has metal spikes on top to protect its cameras from birds, and each camera has a self-cleaning mechanism to stop insects and debris from blurring the lenses. The images they produce travel down multiple high-speed fibre links to the new remote control centre, where they come up on 14 screens which together provide a panoramic view of the runway. "In the remote event that we lost one of those links, there"s always a back-up," said FitzGerald.ROAR OF ENGINES The live sound of the airport is piped into the new control centre so that controllers still hear the planes" engines roaring into life and the reverse thrust of touch down. Jonathan Astill, director of airports at the UK"s National Air Traffic Services added: "We think we"ve got all the risks well covered. So cybersecurity is well covered, for example." For City Airport, the new remote tower, which cost just under 20 million pounds ($28 million) to design and build, is not primarily about saving money. "It benefits safety, and it also benefits efficiency. It enables us to grow in a more efficient way," FitzGerald said. "It"s more safe because actually what we"re doing is providing air traffic controllers with more data." Once flying recovers after the pandemic, City will be able to handle 45 plane movements per hour, up from 40 in 2019. Britain has banned most travel due to COVID-19 but is set to allow people to fly again from May 17. FitzGerald said she was "cautiously optimistic" about the summer. City"s August capacity is forecast to be at about 27% of 2019 levels. The airport"s plan for a remote tower dates back to 2016, when it realised that in order to go ahead with a 500-million-pound expansion plan to fit in extra, bigger planes, it would need to significantly invest in the old control tower. It decided instead to build a new one given the efficiency benefits offered by new remote technology developed by Swedish company Saab (SAABb.ST). FitzGerald said that City"s new tower had attracted interest from big airports and that remote air traffic controllers will become more common in future. Heathrow, Britain"s busiest airport, is considering remote control towers in its future plans. "When we look at our expansion plans that includes remote control towers," chief executive John Holland-Kaye told Reuters. ($1 = 0.7172 pounds)