There are pretty much no aircraft in the skies today that have any remote resemblance to the seldom-used British Aerospace BAe-146. This aircraft might just be the most unique four-engine aircraft to ever take to the skies, as well as one of the most dynamic regional jets ever produced. Today, flying commercially on short-haul hops between smaller destinations that take less than a couple of hours or so is typically done on regional aircraft. These jets (and some smaller turboprop regional aircraft) are the backbone of short-haul operations all across the globe, and they almost all share one thing in common: a twin-engine configuration.
The BAe-146, however, operates these kinds of routes (not in an abnormal capacity, as this is exactly what it was designed for) and does so at a large scale with a four-engine configuration. Historically, smaller jets typically only need two engines to power them, making the BAe-146 a very noteworthy exception. On the other hand, aircraft with four engines are typically significantly more redundant, so there are some reasons that operating these kinds of routes with a high-capacity four-engine jet would be worthwhile. We analyze the fascinating question of why exactly the BAe 146 was built with such a unique configuration.
A Brief Overview Of The BAe-146
The British Aerospace 146, which was later developed into the Avro Regional Jet, is a British short-haul regional jet that was produced from 1983 to 2001, and it was widely regarded as the most successful British civilian aircraft program, with more than 380 models built for paying customers. Originally manufactured by British Aerospace (a company which later became part of BAE Systems), the aircraft line was expanded in 1992 in collaboration with Avro International Aerospace to create the improved Avro RJ series. A further upgrade, which included RJX and new engines, was launched in 1997 and subsequently canceled after two prototypes and one production aircraft were developed.
Originally designed as a quiet, city-airport-friendly jet, the aircraft featured a high-wing cantilever layout and four under-wing geared turbofan engines, along with retractable tricycle landing gear. The jet had low noise output and strong field performance, which made it popular at operationally limited airports like London City. The aircraft family came in three different principal passenger variants, and, beyond service as a regional airliner, was also deployed as a private jet.
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A dedicated freighter aircraft that featured a convertible passenger-freight version, the aircraft also found a second life carrying cargo, especially for operators in search of an aircraft capable of managing heavy loads. The aircraft could also be equipped with optional gravel kits, which allow the aircraft to operate on rough or semi-prepared landing strips. Overall, the BAe 146 combines short-runway capabilities with quiet operations to meet the needs of the demanding regional aircraft market.
Development & Production
Hawker Siddeley, a British aircraft manufacturer, launched the HS. 146 program in 1973, in an attempt to bridge the gap between turboprops and small jets, which it believed existed within the market. The manufacturer designed an aircraft with a T-tail layout and four Avco Lycoming ALF 503H turbofan engines, which the company believed would provide the aircraft with exceptional capabilities. The aircraft’s quad-engine choice was subject to considerable scrutiny, especially due to the jet’s relatively small size. We will discuss this specific decision in more detail later.
The United Kingdom’s government initially funded 50% of the aircraft program’s development when work paused in 1974 due to the global oil shock. British Aerospace (BAe) revived the program in 1978, marketing the aircraft as both quiet and fuel-efficient (something relatively odd given its three-engine configuration. The jet flew on September 3, 1981, and certification followed not long after on February 8, 1983. Initial tests beat the aircraft’s climb targets, and the manufacturer pegged the jet’s break-even at near 250 units, a threshold which the aircraft succeeded in blowing past.
Production of the aircraft started at Hatfield, with major structures built across BAe’s various production sites in the United Kingdom. Some components of the aircraft were made by foreign manufacturers, including American Textron and European Saab. The idea of producing a variant that featured just two engines was also considered, but ultimately not pursued. BAe also considered producing a next-generation model in 2000, but later canceled it and withdrews from the regional aircraft market altogether.
A Deeper Look At The Aircraft’s Design
The BAe 146 was marketed as a relatively simple, low-cost aircraft designed for short-haul, high-density routes. The aircraft simplified operating costs with off-the-shelf components and strict internal cost targets, making it more affordable for operators. The model omitted thrust through reversers, and instead used a large clamshell tail airbrake, which was usable in flight for steep descents, and full-width wing spoilers that deployed upon landing. A high-mounted uninterrupted wing and fixed tailplane reduced parts and complexity, while a toughened undercarriage supported operations from short runways.
Aircraft cabins could be arranged into a five-abreast configuration, something unusual for a regional jet, and it could even be equipped with a six-abreast configuration for higher-density operations. Airline reports suggested that many routes were profitable, as only half of the seats were filled. The aircraft’s lower noise footprint was its signature advantage, and the model offered access to noise-sensitive steep approaches into places like London City Airport (LCY), where the type was one of the only conventional jets permitted to land.
Early aircraft used conventional cockpits and manual flight controls, while later models were equipped with the most advanced flight control systems. The BAe 146 was the second airliner after Concorde to adopt carbon brakes, and it featured an auxiliary power unit that was lighter and more fuel efficient than the jet’s contemporaries.
Why On Earth Did The Model Decide To Operate With Four Engines?
It is now time for us to address the elephant in the room. Why exactly was the BAe 146 built with a four-engine configuration? The BAe 146 uses a set of four Avco Lycoming ALF 502 geared turbofan engines, which were uniquely mounted under the wing. The ALF 502 was derived from the Chinook’s T55 turboshaft, keeping fan tip speeds subsonic via the use of an additional gearbox and adding a high bypass ratio and extra acoustic damping, which gave the jet an exceptionally low noise footprint.
By choosing these four engines, the manufacturer sought to offer additional redundancy and improved takeoff performance on short, hot, or high runways. The jet’s electrical power comes from generators on the outboard engines. These features make the aircraft’s design inexplicably unique.
The ALF 502’s increasingly modular design aimed to simplify the maintenance and tooling procedures. However, the engine family had some notable issues, with electronics that could overheat and trigger an automatic shutdown without an in-flight restart capability. Icing conditions also proved a challenge, and British Aerospace had to overcome these teething issues as it introduced the model to service, according to The Guardian.
Was Producing This Jet With Four Engines A Mistake?
There have been a number of industry observers who have extensively analyzed BAe’s decision to utilize a four-engine configuration for this aircraft. Many of whom pointed to factors like high fuel costs and high maintenance costs as key limitations of this decision.
The argument made through these two factors attempts to apply a modern industry context (where airlines are primarily concerned with fuel costs and maintenance expenses) to a decision made in the 1980s, when the industry’s landscape was very different. Carriers back in the 1980s had a fundamentally different set of needs than they do today.
There are certainly some customers who shied away from the BAe 146 due to its quad-engine configuration. There were reasons why the aircraft carried a higher cost of ownership than other models of the time, as the jet was designed to serve high-volume needs from airports with severe operational limitations.
What Is The Bottom Line?
At the end of the day, the BAe 146 is an extremely unique aircraft that satisfied the needs of a relatively limited market during the 1980s and 1990s. The presence of short-field airports in the United Kingdom and throughout Europe meant that an aircraft with BAe’s operational profile had a unique niche to fill in the market.
However, the aircraft’s four-engine configuration made it not only exceptionally valuable and extremely unique, but also a valuable asset for airlines. The jet could fly all different kinds of routes, especially those that the airline could not fly with a different model. Industry critics have still been quick to highlight how the aircraft’s four-engine configuration held it back.
This is true to some extent, as BAe 146 sales certainly became much more limited following the turn of the millennium, as twinjets became more popular. The lack of four engines, however, would likely have prevented the jet from being as successful as it was during its initial years of commercial deployment.
