The passengers waiting to board at Kenya’s Jomo Kenyatta International Airport include a bunch of UN staffers, a couple of British diplomats and security contractors spottable by their shaved heads and tactical backpacks. The US ambassador to Somalia is also in the line, as are aid workers from a host of charities that are busy trying to alleviate Somalia’s latest drought. They’re all waiting for the morning flight to Somalia’s capital Mogadishu, operated by the United Nations Humanitarian Air Service (UNHAS). This three-times-a-week service is a lifeline to one of the world’s most dangerous cities. With 70 aircraft in 17 countries and an operating budget of €205m this year, UNHAS is the biggest airline you’ve never heard of, and its rugged fleet ferries aid workers in and out of humanitarian crises all over the world.