What is a lie flat seat?

The distinction that matters is flat against angled. A true lie flat seat forms a level surface. An angled lie flat, sometimes marketed as angle flat or sloping flat, reclines a long way but finishes on a slope, and a night on one is spent gradually sliding toward the footwell. A handful of carriers still fly them on secondary routes.

Bed length is the number worth checking, and it is not the same as seat pitch. Most long haul business class beds fall between 76 and 82 inches, which suits the majority of adults, though a passenger over six foot three should look at the specific product rather than assume. Width at the shoulder matters just as much for anyone who sleeps on their side.

Layout decides how usable the bed actually is. In a 1-2-1 cabin every passenger reaches the aisle without climbing over a sleeping neighbour, which is why that arrangement has become the standard for new aircraft. On older 2-2-2 cabins the window passenger has to step over someone, and that alone changes how much of the flight is spent asleep.

First class takes the idea further with a separate bed rather than a converting seat, and a growing number of business class products now add a closing door. Neither is required for a good night. A well designed flat bed in a 1-2-1 cabin does most of the work, and the remaining difference is comfort rather than category.