Widebody versus narrowbody

A narrowbody has a single aisle and a fuselage roughly three to four metres across. A widebody has two aisles and a fuselage of five to six and a half metres. That one difference cascades into almost everything else: how many people fit, how fast the aircraft can be boarded and turned around, whether standard cargo containers fit underfloor, and how far it makes economic sense to fly.

Widebodies exist to cross oceans with enough people to justify the trip. Narrowbodies exist to fly short and often — and they are what most passengers actually experience, because the vast majority of flights taken worldwide every day are single-aisle.

The line between them is blurring. The A321XLR is a narrowbody with transatlantic range, flying routes that once demanded a widebody. It is the most interesting fight in commercial aviation right now.