Southwest Airlines has celebrated its first 'unmanned' flight, with an all-female crew of two pilots and four flight attendants undertaking a journey between the US cities of St. Louis and San Francisco, California.

Others were quick to take to social media to show their support for the all-female service between St. Louis and San Francisco.

Southwest is America's third biggest airline and the seventh largest in the world, with around 49,000 employees. In the UK, male pilots outnumber female pilots 16 to 1, rising to 33 to 1 at the nation's biggest holiday company, Thomson.

Writing in The Independent this year, Simon Calder said: "When I checked on the flight-deck gender split three months ago [January2017] with all the leading airlines serving UK passengers, a remarkably consistent pattern emerged: at British Airways, easyJet, Monarch and Ryanair, just 6 per cent of crew are female."

He also noted that only one flight in roughly 300 flights to and from the UK is flown by two women; 17 have have one male and one female pilot; and the remaining 282 are two-man operations.