Boeing 737-400 vs. Boeing 767-400ER

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.

The Boeing 767-400ER is an advanced, wide-body aircraft developed by Boeing as part of the evolution of the 767. Introduced at the beginning of the 21st century, this variant is an extension of the popular 767 family, designed to address the increasing demands of the airline industry for higher capacity and extended range.

As a later addition to the 767 series, the -400ER variant built upon the established reputation of its predecessors by offering enhancements in both size and performance. The development and subsequent introduction of this model into the commercial market were part of Boeing's strategic response to the competitive dynamics of the aviation industry. The 767-400ER's production started in the late 1990s, with the aim of providing airlines with an aircraft that combined operational efficiency with increased passenger capacity.

The aircraft measures 61.4 meters (201.3 feet) in length, featuring an extended fuselage to accommodate more passengers. The wingspan of the 767-400ER is 51.9 meters (170.3 feet), and it has a wing area of 290.7 square meters (3129.1 square feet). These dimensions contribute to the aircraft's aerodynamic efficiency, particularly important for long-distance travel. Equipped with a choice of General Electric CF6 or Pratt & Whitney 4000 series engines, the 767-400ER offers robust performance with a total maximum thrust of 540.0 kN (121,200 lbf). This thrust capacity, combined with a fuel storage of 90,700 liters (23,960 US gallons), enables the aircraft to cover a range of about 10,400 kilometers (5,616 nautical miles), making it well-suited for extended-range operations.

In terms of passenger capacity, the typical layout of the 767-400ER seats up to 296 passengers, with a maximum capacity of 375 passengers in a high-density configuration. The cabin is generally arranged in a dual-class setup, featuring a standard 7 abreast, 2-3-2 seat arrangement in economy class.

Competing with the Airbus A330-200, the 767-400ER was introduced to provide airlines with a modernized option of the 767, balancing the familiar operational characteristics of its predecessors with the needs of contemporary long-haul travel. Notable airlines of the Boeing 767-400ER include Continental (United Airlines) and Delta Air Lines. The aircraft's combination of extended fuselage, increased passenger capacity, and range efficiency mark it as a significant evolution within the 767 family, catering to the specific requirements of modern commercial aviation. Only 37 units of the -400ER were ever produced.