narrowbody
An airliner capable of seating, at most, six or fewer passengers in a single row of economy seating, with one aisle.
narrowbody: single-aisle airliner with tight cabin width
A narrowbody aircraft has a fuselage diameter of roughly 3.5 to 3.8 meters, constraining the interior to one passenger aisle with seats on both sides. The Boeing 737 and Airbus A320 families are the workhorses of this category. These jets dominate short to medium-haul routes, typically carrying 120 to 210 passengers depending on configuration and aircraft generation. The single-aisle layout keeps weights low and operating costs manageable compared to their widebody cousins.
The cabin width dictates the seating grid. A narrowbody almost always seats six across in economy: three on each side of the aisle, with two or three seats per section. This geometry is why the term exists, it is a structural and commercial reality baked into the airframe. The cabin pressure differential, cargo volume, and emergency evacuation procedures all hinge on this single-aisle constraint. A widebody, by contrast, seats eight to ten across with a center aisle running between two pairs of aisles.
Maintenance and structural implications
From a maintenance standpoint, narrowbody fatigue cracks and cabin pressure leaks are common failure modes because these aircraft see high cycle counts. A 737 or A320 might complete four to six cycles per day on short routes, where each pressurization and depressurization stresses the fuselage. Inspection schedules for narrowbody airframes are accordingly intense; cracks around door frames, window cutouts, and fuselage splices are typical recurring issues.
Narrowbody design also means tight service access. Engine removal, landing gear overhaul, and avionics swaps require careful scheduling and specialized equipment because floor space is limited. Many maintenance tasks that would be straightforward on a widebody demand careful choreography on a narrowbody to avoid damage to adjacent systems in the compressed cabin.
The narrowbody category has shifted steadily over decades. The 737 Classic and A320-200, delivered from the 1980s onward, seat around 150 to 180. Newer engines and composite materials in the 737 MAX and A320neo generation allow similar or slightly larger payloads with better fuel economy. This incremental growth keeps the category competitive against regional widebodies and turboprops on marginally longer routes, maintaining narrowbody dominance in global airline fleets.