Boeing 737-300 vs. Boeing 737-400

The Boeing 737-300, launched in the early 1980s, is a seminal model in the 737 family, known for ushering in the era of modern narrow-body jetliners. As the first of the 737 Classic series, it was developed to meet the growing demand for more efficient and higher-capacity short to medium-haul aircraft. Compared to the Original 737 models, the -300 featured new wings, a redesigned tailfin, and improvements inside the cabin. Fast forward a bit, the 737-300 was eventually replaced by the 737-700 of the Next Generation series.

The 737-300 stretches 109.6 feet (33.4 meters) from nose to tail, with a wingspan of 94.5 feet (28.8 meters). This aircraft was Boeing's answer to the need for a larger capacity in the single-aisle market, accommodating 128 passengers in a typical two-class layout. Its increased length over its predecessor, the 737-200, allowed for additional seating, making it a more economical choice for airlines.

Equipped with two CFM International CFM56-3B1 engines, the 737-300 produces a total thrust of 44,000 lbf (196.0 kN). This enhancement in power, combined with a fuel capacity of 5,310 US gallons (20,100 liters), extended the aircraft's range to 2,376 nautical miles (4,400 kilometers). The 737-300's cruise speed of 495 mph (796 km/h) made it a swift and efficient option for airlines, reducing flight times on popular domestic and regional routes.

The 737-300 marked a shift in the commercial aviation landscape, competing with models like the McDonnell Douglas MD-80. Its launch was pivotal for Boeing, demonstrating the company's ability to innovate and adapt to market shifts. The 737-300's popularity was driven by its improved efficiency, greater capacity, and enhanced performance, meeting the needs of airlines expanding their short-haul operations.

Major carriers such as Southwest Airlines and United Airlines incorporated the Boeing 737-300 into their fleets, capitalizing on its operational advantages. The American carriers purchased a majority of the -300, with 299 units between the two airlines. The aircraft's role in these fleets was significant, as it enabled airlines to offer more frequent services and open new routes, particularly in the domestic and regional markets.

The Boeing 737-400, part of the 737 Classic series, is a narrow-body, twin-engine airliner developed to meet the evolving requirements of the short to medium-haul market. First introduced in 1988, the 737-400 expanded upon the success of its predecessor, the 737-300. The -400 variant entered manufacturing shortly after finalization of design plans between Boeing and launch customer Piedmont Airlines (later merged into US Airways). It gives increased capacity and range, offering an option in between Boeing's 737-300 and the 757-200.

The fuselage incorporated a key 8 foot expansion to enable typical accommodation for up to 170 passengers in a 2-class layout. Other changes included increased weights and structural reinforcements, enhanced avionics/flight controls, and higher thrust CFM powerplants required for the heavier max takeoff figures. Cost efficiencies were achieved keeping cockpit continuity with the ubiquitous 737 flight deck suite.

Spanning 119.6 feet (36.5 meters) in length with a wingspan of 94.5 feet (28.8 meters), the 737-400 was designed to accommodate the growing demand for larger single-aisle aircraft. The aircraft typically seats 144 passengers, providing more space and comfort compared to earlier models in the series. This increased capacity made the 737-400 an attractive option for airlines seeking to transport more passengers on popular routes, without the need for a larger, wide-body aircraft. Equipped with two CFM International CFM56-3C1 engines, the 737-400 delivers a total thrust of 44,000 lbf (196.0 kN). This engine configuration, combined with a fuel capacity of 5,310 US gallons (20,100 liters), allows the aircraft to achieve a range of 2,079 nautical miles (3,850 kilometers).

In the competitive commercial aviation market of its time, the Boeing 737-400 contended with models like the McDonnell Douglas MD-80 series. Its introduction marked another milestone for Boeing in the evolution of the 737 family, solidifying the company's position in the market for short to medium-haul airliners. Airlines such as Alaska Airlines, Turkish Airlines, and British Airways incorporated the Boeing 737-400 into their fleets. The aircraft's operational role was significant, enabling these carriers to expand their route networks and increase flight frequencies, particularly in domestic and regional markets.