"We are not considering standing-only accommodations, nor do we have any plans to do so," says spokesman Nick West. "Among other things, stringent regulatory requirements - including seats capable of withstanding a force of 16 Gs - pretty much preclude such an arrangement."

Sixteen Gs is 16 times the force of gravity, so the seats must be strong enough - and strongly secured enough - not to topple over like dominos in the event of a crash. Vertical seats would require more reinforcing than standard seats, because the passenger's centre of gravity is higher.

"More reinforcement means heavier planes which use more fuel, and that's the last thing Ryanair wants," says David Learmount, operations and safety editor of Flight International. "They'd end up having to reinforce the floor, and possibly the bulkheads too if the seats need to be secured top and bottom. And how many points of contact would the straps have to have? Across the body, perhaps securing the ankles, the knees, the head."

Which sounds like the Hannibal Lecter way to fly.