Collision alarms in the cockpits of both Boeing 737 aircraft went off, warning that they were too close together Get Travel Insider with Simon Calder. A newsletter packed with tips, deals, inspiration, and the latest travel news Get the Travel Insider newsletter with Simon Calder Get the Travel Insider newsletter with Simon Calder Email * SIGN UP I would like to be emailed about offers, events and updates from The Independent. Read our Privacy notice Pilots of two Southwest Airlines planes were