Budget airlines tend to be more efficient as they seat as many passengers as possible 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 Air travel is famously one of the hardest sectors to decarbonise, and