The Boeing 787 Dreamliner innovates in multiple key areas beyond just fuel efficiency. From a technological standpoint, it’s one of the most sophisticated planes ever developed, featuring landing gear doors that automatically open on the larger 787-9 and 787-10 variants, for instance, or dual heads-up displays for the pilots as standard. It also boasts the most powerful electrical system of any airliner ever, and it also introduced dimming passenger windows, removing traditional window shades in the process.

One of the most sophisticated systems present onboard the Dreamliner is its ‘Gust Load Alleviation System’ (GLAS). This is an advanced system intended to combat turbulence in-flight, taking a proactive approach to ensure a smoother ride for passengers. It can even help to reduce strain on the aircraft’s structure, allowing Boeing to further optimize its design and construction to be as light as possible. As such, this background system is one of the most important on the 787.

The Gust Load Alleviation System On The 787

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As with any aircraft, the 787 features a system of sensors and ports to obtain critical flight information. On the 787, the onboard flight computers, in addition to providing data to the pilots, also analyze the information to make adjustments to the control surface deflections. It automatically commands the aircraft’s ailerons, elevators, and rudder without pilot input, helping to counteract sudden changes in lift. This helps keep the aircraft’s wing bending motion constant, and the control surfaces can modulate up to 50 times per second.

On older airliners, the aircraft’s autopilot will also make adjustments for turbulence, but only as a reaction to maintain a stable flight path. The Dreamliner’s GLAS takes a proactive approach, reducing the impact that turbulence has on the flight rather than solely correcting it. Boeing testing showed that the GLAS reduces the vertical impact of turbulence by 60% to 70%, although the manufacturer also states it cannot fully eliminate the impact of turbulence.

In addition, when pilots encounter turbulence during manual flight, they’re on their own. With the 787, however, the lateral gust suppression component remains active even when the autopilot is disconnected, subtly adjusting the aircraft’s ailerons, flaperons, and speedbrakes to counter rolling disturbances from gusts or turbulence. Meanwhile, the vertical component has the computer deflecting the flaperons and elevators symmetrically, a function that is only active when the aircraft’s autopilot is engaged in Altitude Hold or VNAV flight modes.

The Benefit Of The 787’s GLAS

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The most direct benefit of the GLAS is that it results in smoother rides. Beyond mitigating stress for the nervous flyer, this also has material safety implications, because although turbulence does not pose an immediate hazard to the safety of the aircraft itself, it can still be dangerous for passengers and crew. In the US, on average, over 50 people are injured by unexpected turbulence, usually those not wearing their seatbelts, and the 787’s GLAS helps mitigate this threat.

In addition, the presence of the GLAS reduces structural strain on the aircraft’s structure. While turbulence does not pose an immediate threat to an aircraft’s structural integrity, it does contribute to fatigue, as the wings, in particular, experience sudden spikes in load. The GLAS works to dampen the impact of these load spikes, reducing the amount the wings flex during sudden gusts and thereby reducing the strain on the wings. Over time, this leads to significantly lower fatigue.

Any airliner is certified to handle far more than what even the most severe bout of turbulence can dish out, but this requires significant structural reinforcement. With this system, engineers were able to further optimize the aircraft’s weight, making the wing lighter, and this also increases the fatigue life of these components. This has material benefits for airlines, which are always looking to reduce costs. With this system, airlines can save on maintenance costs because the components last longer under reduced stress.

Earlier Implementations Of Similar Systems

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A gust alleviation system like what’s seen on the Dreamliner is primarily possible through using a fly-by-wire flight control system. Concorde was the first commercial aircraft to feature a fly-by-wire system, while the Airbus A320 was the first airliner with a digital fly-by-wire system. The A320 and subsequent Airbus models, along with the Boeing 777, feature limited load alleviation systems to dampen the effects of turbulence, using the ailerons or the rudder to respond to sudden gusts.

The aircraft that pioneered a comprehensive gust alleviation system similar to that of the 787, however, is the Northrop Grumman B-2 Spirit bomber. This innovative flying wing also uses a load alleviation system to proactively respond to wind gusts, but the B-2 doesn’t utilize this system just to reduce the impact of turbulence. The B-2 Spirit was designed to be inherently unstable, requiring the presence of a fly-by-wire system to make constant adjustments just to allow it to fly.

The B-2’s flight control systems constantly damp oscillations and make load adjustments to ensure flight path stability, in a manner extremely similar to the GLAS on the 787. While it wasn’t the first aircraft to alleviate load spikes from gusts, it was one of the most thorough implementations of such a system at the time, and it also demonstrated that an aerodynamically unstable aircraft could rely on computer adjustments to maintain steady flight. Today, the 787 now applies similar principles to dampen turbulence.

Other Ways That The 787 Provides A Superior Onboard Experience

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Beyond the smoother ride, another difference that Dreamliner passengers will notice from older aircraft is that the 787 is extremely quiet. While many consider the Airbus A380 and A350 to be the quietest airliners in service, the 787 is hardly any louder than either, thanks to its high-bypass engines and innovative engine nacelle chevrons. In addition, the 787’s carbon-composite construction allows for greater pressurization, resulting in lower cabin altitudes. These benefits are particularly important for the Dreamliner, given its extensive use on some of the world’s longest flights.

The 787’s dimmable windows have been controversial, with some passengers finding the system slow and less effective at blocking out light versus traditional window shades. In addition, cabin crew can digitally lock all the windows. What’s not controversial, however, is the fact that the 787 has the largest passenger windows of any in-production airliner. Positioned high and larger than most laptops, they allow for a significant amount of natural light, enhancing the onboard experience. As a comparison, the Airbus A350, the 787’s technological contemporary, has smaller windows than a Boeing 777.

The 787 was designed with the Boeing Sky Interior, an innovative interior design standard that provides a modern, more comfortable aesthetic for passengers. Due to 787 delays, the Boeing Sky Interior originally debuted on the Boeing 737NG and incorporates advanced mood lighting with organic curves and high ceilings. In addition, the 787 also comes with large, pivot-style overhead bins, designed to fit carry-on bags on their sides, allowing more bags per bin.

Comparing The 787’s GLAS To The A350

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As previously mentioned, the Airbus A350 is the 787’s technological equal, even if the two compete in different market spaces. Similar to the 787, the A350 also features a gust load alleviation system; unlike the Dreamliner, however, this is not a standalone system. Instead, the gust alleviation load functions on the A350 are an integrated part of the aircraft’s overall flight envelope system, with the aircraft managing load spikes as part of its general goal to maintain a stable flight path.

Unlike the 787, the A350 generally retains its gust load alleviation functions during manual flight, as Airbus’s fly-by-wire logic sees pilots commanding a G-load and pitch rate with the sidestick, which is then interpreted by the flight computer on how to deflect the control surfaces. The 787’s fly-by-wire logic adds an airspeed element, and in practice, attempts to simulate the experience of flying an older aircraft with a fly-by-cable system.

This is one example of how these two innovative widebodies differ in the technological improvements they incorporate to boost efficiency, reduce costs, and improve the passenger experience. The A350, for example, only recently introduced dimming windows with the introduction of the ‘New Production Standard’ (NPS), while the 787 has included them from day one. To reduce landing gear retraction time, the 787’s main landing gear doors automatically open after rotation, while the NPS A350 simply reduces the gear retraction time altogether. While they differ substantially in method, they both achieve the same results of being the most efficient long-range airliners on the market.