Airbus' Clever Engineering Tricks That Made The A330 Become The "Butter Machine"

Published Nov 13, 2026, 9:00 PM EST Passionate about promoting aviation, the beauty of flight and the science behind it, Antonio is an avid reader of aviation magazines and books, and he loves visiting airshows all over the world, taking photos and writing about airplanes and helicopters as well. He is currently based in Palermo, Sicily. The Airbus A330 has earned an unusual nickname among aviation enthusiasts: the “Butter Machine.” The name comes from its reputation for exceptionally smooth landings, often marked by a gentle first contact between the rear wheels and the runway before the rest of the landing gear settles. So what exactly is Airbus doing under the wings? Which parts are true engineering tricks, and which are folk wisdom repeated on aviation forums for twenty years? Even the experts disagree about why the gear sits at an angle, and the answer changes how you should read every “smoothest landing ever” video. Stay with us, because the most surprising answer sits in the middle of the article, and it comes from pilots who say the landings that look smoothest from the fence are not always the ones passengers feel as smooth. Let’s start with the part everyone can see. The Airbus A330’s Unusual Four-Wheel Landing Gear Credit: InsectWorld | Shutterstock The first clue is the tilt. According to Flightradar24, the A330 is often called ‘The Butter Machine’ because of its smooth landings, and it names the main landing gear as the jet’s easiest identifier: two sets of four wheels, tilted backward. Canada’s Transportation Safety Board (TSB) describes the same arrangement in an A330 investigation report: each bogie carries four wheels in a twin-tandem layout, and the bogies are inclined so the rear tires touch the runway first. Flightradar24 adds a useful contrast: the four-engine A340 carries an extra center landing gear, while the A330 relies on its two main bogies alone, which puts even more attention on how those two units behave. That arrangement becomes more interesting once the wheels actually meet the runway. According to the same report, forces are transferred gradually when the wheels touch down, instead of arriving through all eight main tires at once. Simple Flying’s explainer on why the A330 lands so smoothly adds the supporting cast: oleo-pneumatic shock absorbers, a balanced bogie design, titanium and corrosion-resistant steel, and two landing gear control units that alternate for reliability. The wheels, however, cannot simply remain tilted on their own. Something has to position the bogie before touchdown and control its movement as the aircraft transitions from flight to the runway. The Pitch Trimmer: The Hydraulic Mechanism Behind The A330’s Tilted Gear That job belongs to a hydraulic ram called a pitch trimmer. Pilots and engineers on the PPRuNe forum describe it as the part that sets the bogie nose-up when the gear is selected down, and a research paper on tire heat at touchdown says it lifts the front wheels of the bogie and lets the rear wheels descend around the bogie beam. The same paper adds that the pitch trimmer can act like a shock absorber. That damping role is not just forum talk. A patent for a variable-damping pitch trimmer explains that the actuator positions the wheels before touchdown, helps stow the gear, and also damps the motion of the bogie beam relative to the leg. Meanwhile, a shortening mechanism pulls the shock absorber up inside the leg during retraction, which shrinks the gear so it fits into a compact bay. Simple Flying notes that Airbus had not used such a feature on many earlier models. The TSB report adds that the bogie beam pivots at its center on the shock strut, and that the beam position is always the same when the gear is selected. That last point is important because it separates two jobs that are often blended together when the A330’s landing gear is discussed. The pitch trimmer clearly helps position and damp the bogie, while the shortening mechanism helps package the landing gear inside the aircraft. That raises a bigger question about the original purpose of the backward tilt itself. Why The A330’s Landing Gear Is Tilted Backward The reason for the angle is less settled than the nickname might suggest. In a PPRuNe thread on landing gear lean, a contributor insists that simple geometry points to storage, noting that the tilt exists so the bogie fits the bay. Another poster counters that the A330 and A340 are a special case, claiming the nose-up tilt is intentional and works a bit like the semi-levered gear on the Boeing 777-300ER, improving clearance under the aft fuselage. Enthusiasts keep a dedicated Airliners.net thread on A330 main gear bogie tilt, while The Points Guy reports that wheel orientation is mostly a space-saving choice, even though pilots generally agree that trailing-link gear produces the most flattering landings. In other words, the tilt may exist for storage, yet it still shapes the touchdown. Designers rarely mind when a packaging solution doubles as a comfort feature. The landing gear explains why the A330 touches down in stages, but it does not explain everything passengers see or feel during the final seconds of a landing. Once the aircraft is close to the runway, the flight-control system and the wing become just as important. Airbus A330 Flight Controls & The Art Of A Smooth Landing Credit: sorao.211 | Shutterstock The A330 was designed to give pilots familiar handling near the runway even though it uses fly-by-wire controls. According to the Australian Transport Safety Bureau (ASB), flare mode replaces the normal load-factor law with a flare law, letting crews use the same landing technique as on non-fly-by-wire aircraft. Airbus’ own Safety First magazine says the flare should begin around 40 feet (12 meters) above the runway on the A330, A340, A350 and A380, compared with 30 feet (nine meters) on smaller Airbus jets. The same article warns that a steeper approach slope than the nominal three degrees may call for an earlier flare, reminding pilots that the software supports them rather than replacing their timing. Handling plays a part too. Many pilots describe the A330 as stable and predictable, with an older-generation wing that gives a slightly heavier control feel than the A350. Members of the Infinite Flight Community go further, crediting a wing size and strong ground effect, though that is speculation rather than confirmed engineering. A pilot on a PPRuNe flare-height thread offers a more practical view, saying the A330 and A340 settle nicely with a 40-foot (12-meter) retard and a smooth rotation. With the gear tilted, the bogie damped, and the flare law handling the final phase, the ingredients for a smooth touchdown are certainly there. There is still one catch, though: the first contact with the runway is not necessarily the end of the landing sensation. Why Do Some A330 Landings Still End With A Thump? Credit: JetKat | Shutterstock On a PPRuNe thread about hard A330 landings, pilots describe how the aircraft can touch down beautifully on the rear wheels, then float along the runway before the front wheels come down heavily. Their advice is to touch down on the rear wheels, then pitch down firmly enough to bring the front wheels gently onto the runway while speed remains, which is exactly what they say the autopilot does on an autoland. That distinction changes how the A330's landing should be judged from the ground. A long, graceful hold-off can look almost perfect to somebody watching from the fence while producing a noticeably firmer second contact for people inside the aircraft. The sequence is therefore less about eliminating every bump than about controlling when each part of the landing gear takes the load. Timing matters for another reason. A separate thread about A340 touchdowns explains that applying reverse thrust as the rear axle lands can make the aircraft drop onto the front axle once the ground spoilers kill the lift, and that a higher pitch attitude at the flare makes the thump worse. A pilot in the same thread says the A330 behaves similarly, and that the cure is to flare for the rear axle, derotate smoothly until the front axle is down, and only then use reverse. Ground spoiler logic, according to an ATSB investigation of an A330 landing, depends on weight on both main gears plus either a radio altitude below 6 feet (1.8 meters) or a wheel speed above 72 knots (133 kilometers per hour). One Airliners.net user also lists three distinct bumps: rear wheels, front wheels, then the nose wheel. The sequence also explains why the A330's landing gear remains interesting beyond the aircraft itself. Airbus did not stop developing large-aircraft landing gear after the A330, and some of the same principles appear on later widebodies. A330 Landing Gear Design Lives On In Newer Airbus Widebodies Credit: Denver International Airport The A330's basic approach clearly survived into later Airbus designs. As Simple Flying previously explored, the A350-1000’s six-wheel bogie is built, so the rear wheels typically touch down first, stabilizing the aircraft before the forward wheels settle, which reduces pitching forces and improves comfort. The A380 needs 20 tires on its main gear, which shows how far the same weight-spreading problem can be pushed. Both aircraft inherit the same basic logic: share the load, sequence the contact, and let the shock absorbers do the rest. Airbus also launched the A330neo with new engines and winglets that improved per-seat fuel economy by 14 percent, but the family's touchdown personality barely figures in that story. That is what makes the landing gear such an interesting part of the A330's legacy. The aircraft has evolved through new engines and winglets, but the gear that helped create the Butter Machine reputation remains fundamentally part of the family. As the NEO version continues to fly across more route networks, pilots, passengers, and spotters still get the same butter landings.