A group of US pilots has filed a lawsuit over the country's federal mask mandate, which stipulates that all passengers must wear a face covering on public transport, including on flights and at airports. The 10 pilots span several airlines JetBlue, Southwest Airlines and American Airlines " and claim that the Federal Transportation Mask Mandate is "an illegal and unconstitutional exercise of executive authority." Filed in the US District Court for the District of Columbia, the suit alleges that the mask mandate, first introduced in February 2021, has caused "chaos", and claims the CDC "ignored countless scientific and medical studies" disproving the effectiveness of masks in preventing the spread of Covid-19. Federal Aviation Administration (FAA) data shows that masks have been linked to a surge in disruptive passenger behaviour on board American flights - of 5,981 onboard disputes recorded on the country's airlines last year, 72 per cent were related to masks. The plaintiffs have also requested that authorities "remove all signs informing passengers" to wear a mask, and that they be awarded any costs and fees they incurred within the course of the suit. Following an extension last week, the mask mandate is currently due to stay in place until at least 18 April. The news comes after an announcement from London's Heathrow airport that passengers are no longer required to wear a face covering. The change applies across all of Heathrow's terminals, bus and railway stations and office spaces.