The Boeing 737-400 is another member of the "737 Classic" series, introduced in the late 1980s. It is essentially a stretched version of the 737-300, designed to meet airline demand for a higher-capacity aircraft for short-to-medium-haul routes, particularly for charter and leisure operations.
Here are its key characteristics:
- Stretched Fuselage: The most defining feature of the 737-400 is its longer fuselage compared to the 737-300. Boeing stretched the airframe by adding fuselage plugs both fore and aft of the wing, increasing its overall length.
- Increased Capacity: This stretch allowed the 737-400 to typically seat between 146 and 188 passengers in a single-class configuration, making it a competitor to aircraft like the McDonnell Douglas MD-80.
- CFM56 Engines: Like the 737-300, it was powered by the same fuel-efficient and quieter CFM56-3 high-bypass turbofan engines, featuring the distinctive flat-bottomed nacelles to maintain ground clearance. Due to the increased weight, these engines were often slightly uprated compared to those on the -300.
- Wingtip Skids: A notable visual difference on some -400s (though not all) was the addition of a small tail skid located beneath the aft fuselage. This was a precautionary measure to prevent tailstrikes during takeoff rotation, which could be more common with the longer fuselage.
- Avionics: It shared the updated digital cockpit and avionics of the 737-300, retaining the two-person flight deck.
- Role: The 737-400 became a popular choice for airlines needing more seats on busy domestic and regional routes, often replacing older, smaller aircraft.
In summary, the Boeing 737-400 took the successful design of the 737-300 and scaled it up to offer greater passenger capacity, making it a highly effective and popular aircraft for airlines looking to maximize seating on their short and medium-range networks during its operational heyday. Many have been retired from passenger service, with some converted to cargo use.
