58

What you saw is called a speed brake, which is one of the functions of the spoilers. From the Boeing 737 NG FCOMv2 (9.20.5 Flight Controls - System Description): Flight Spoilers Four flight spoilers are located on the upper surface of each wing. Each hydraulic system, A and B, is dedicated to a different set of spoiler pairs to provide isolation ...


57

Roll control is provided by 2 flaperons, 2 ailerons, and 14 spoilers. Spoiler panels 4 and 11 are controlled mechanically rather than electrically. They are driven directly from control wheel deflections via a control cable. In case of compete electrical loss, limited roll control is available until the electrical system is restored. This probably ...


30

Spoilers have many uses, but first I want to distinguish types of spoilers. Airplanes will typically have ground spoilers and flight spoilers and they work like they sound. Ground spoilers only open up on the ground -- these are usually much more detrimental to lift than the flight spoilers. Flight spoilers open when actuated by the pilots Another type of ...


26

They can. The Airbus A318 and Embraer E190 both do this in steep approach mode. You can see spoilers extended in this video of a A318 landing and a similar approach in an E190 at London City Airport. Going back further, the Lockheed L-1011 did this with a system called Direct Lift Control. When landing flaps were selected, spoilers raised a set amount. ...


25

Very frequent. Modern airliners are certainly fairly slippery, but it's not so much that they're super-gliders that we can't wrestle down onto the ground. It's more a function of busy airspace than a property of the aircraft. When you remove power from any aircraft, it's going to descend - the only question is the rate. I promise you that if you found ...


20

Surfaces sticking out ahead of the Centre of Gravity act in an unstabilising manner: any dissymmetry will want to amplify itself. A dart thrown with the feathers first is in an unstable equilibrium and will very quickly turn around 180º. Surfaces behind the CoG act as stabilisers, keeping the nose pointing forward. An aeroplane has vertical and horizontal ...


17

Spoilers are used to shed energy when the aircraft is too fast or too high. That means they need to be used when the aircraft is flying fast and are designed accordingly. On the other hand flaps are used to increase lift and when flying fast, there is plenty of lift, so there is no point in using flaps at high speed and therefore they are not designed for ...


17

There are a couple of reason for the presence of thrust reversers: To reduce wear on the brakes. To provide a margin of safety (for example in wet conditions). In 1995, NASA carried out a survey on airlines Why Do Airlines Want and Use Thrust Reversers?. The results of the survey, though dated, give an indication of presence of thrust reversers. The ...


16

Downward aileron travel must be restricted when flaps are deflected. Since flaps change the local incidence on the flapped part of the wing, the outer wing will experience an increase in its local angle of attack. The increased suction over the inner wing will accelerate not only the air flowing over the inner wing, but also that air which will flow over the ...


16

The main issue is the need to manage the vertical sink rate of your 100000+ lb aluminum trash can and the risks of hard landings. Although they are often called speed brakes, the main effect of flight spoilers is to increase sink rate (without speeding up). On a landing approach at typical jet speeds of around 130kt you don't want to be descending any more ...


15

Spoilers reduce lift potential when deployed and increase drag. This makes them doubly helpful at high speed: Not only will the aircraft slow down, but the pilot has less of a chance to break something important when they are deployed. Contrast this with flaps: They create only a moderate drag increase, but vastly increase the potential lift. If they would ...


13

There are two reasons I can think of off the bat: Its possible the controller asked them to hold a slow speed due to increased traffic ahead. The brakes may have been deployed to match the speed requested. I have heard this called on occasion over the radio in the terminal area I fly. The controller cleared them for a steeper decent than usual this would ...


13

The table in the report omits a condition. Here is the ECAM message in full: The limitation applies when the aircraft is in emergency electrical configuration (run by the ram air turbine), which is one way to have the flight laws degraded. The manual does not give a direct reason (not unheard of), but in fact there's more than one reason. ► As a quick ...


12

Certainly! Spoilers are used whenever there's a need to descend a little faster than the aircraft will with idle engines and just flying downwards with it's own drag. This happens quite often. Pilots will try to avoid it since it's not efficient use of fuel, but they usually can't in busy airspace where stuff happens quickly and there are fixed procedures to ...


12

Location choice Note: the BAe 146 / Avro does have wing spoilers. Air brakes are in most cases mounted directly on the fuselage. Forward mounted air brakes would disrupt the airflow to the wings and engines, so the designers are left with three choices: above, under, or at the rear / on the sides. Under, like on the Aero L-39, works well1 if the air ...


12

Though your photos refer to a specific commercial airliner, your question is general, so I will describe a more specialized use case for speed brakes. A glider (also known as a sailplane) has no engine, and it is designed to have a very high glide ratio so that it can travel further between sources of lift. If a glider were to come in for a landing without ...


11

It depends on the aircraft (and conditions). In some aircraft like the MD-11, the deployment of ground spoilers causes a nose up pitching moment- in such a case, the spoilers should be deployed after nose landing gear touches down. An example is the incident in Hawaii where the aircraft, a MD-11 exhibited a pitch up tendency during landing and the pilot had ...


11

This HD video of an A320 landing in Chicago shows that the ailerons move all the time during the approach, although the excitations are very limited from the moment the final flaps are selected. It seems there is some kind of limiting functions activated. Airbus has various versions of the aileron and spoiler control system on the A320 family. It is ...


11

Those are spoilers...not speed brakes. They do increase drag, but their primary function is that they kill lift. They allow the aircraft to lose altitude rapidly without pointing the nose downhill and picking up speed. You will also see them deploy upon touch down. At high speeds they increase drag and thereby aid in deceleration, but again they kill ...


9

Indeed spring-loaded or not, the pilot will keep a hand on it. But in the latter case, they can still use that hand, and return to the lever, without abrupt changes to the plane's pitch/configuration. An example busy scenario is a rapid decompression descent. Source: YouTube; annotated If you continue watching the video past step 4 (deploying the speed ...


8

Air brakes increase drag with little change in lift. The following image shows the air brake being used in BAe 146 "Eurowings bae146-300 d-aewb arp" by Adrian Pingstone - Own work. Licensed under Public Domain via Commons. Spoilers both increase drag and reduce lift- basically, they change the lift-to-drag ratio. Sometimes, they are also used as control ...


7

https://www.eucass.eu/doi/EUCASS2017-318.pdf Above shows a configuration where the flaps and spoilers are deployed. The blue line shows the vertical velocity of the wing's wake, which is indicative of the lift being generated. Since the effect of the flaps lessens outboard, that causes the downforce shown above near the end of the wing due to the spoilers. ...


7

Spoilers lower lift and increase drag on the side where they are deployed. Symmetric spoiler deployment, therefore, is for slowing down. Asymmetric deployment not only creates a (small) rolling moment, but primarily a yawing moment which helps to counteract the adverse yaw created by ailerons, especially at the high lift coefficient at takeoff and early ...


7

The added complexity is a valid point. However, the additional braking option provides enough benefits to offset the added cost. Also, it is not accurate that credit is never given for reverse thrust. Per 14 CFR §25.109, when calculating accelerate-stop distance, reverse thrust is not considered for a dry runway, but: May be included as an additional ...


6

A proximity sensor is any sensor that detects whether there is something in its proximity (within specified distance). There are many kinds of proximity sensors (optical, magnetic, capacitive etc.) that detect different kinds of target objects and to various distances. In this case, proximity sensor is used to detect position of the spoiler. Proximity ...


6

The BAe Jetstream 31 is one of a few aircraft that had a "lift dump" flap position after touchdown. It is not "more than 90°", but it is quite effective. (Jetstream 31 Lift Dump in action; YouTube)


6

Spoilers are called spoilers, because they work by spoiling lift. To slow the aircraft, or make it descend faster, it needs to dissipate the energy and that means increase drag. Disrupting the airflow over the wing creates a lot of drag due to stagnation behind the spoilers, and additional induced drag as the lift distribution is pushed further from optimal....


6

Please read the entire answer to understand the matter even if the answer goes a bit beyond the question. On the A320 wings you have panels that may open upward and that could be used to fulfill 3 different functions: ground spoilers, speed brakes, roll spoilers. The outer panels are used in addition to the ailerons for roll function, that is helping the ...


6

One reason is that any device you want to use as a lift dumper needs to be able to be instantly retracted and this is really difficult to do with a flap. On an airliner when the lift dumpers come up, if you slam the thrust back up to TO, they immediately come back down. A flap system with its slow moving drive line can't do this, and it's enough that it ...


6

As you can see on the photo, the flaps are slightly extended, allowing the aircraft to fly at a lower airspeed. This is common for aircraft to do during an approach, to keep a constant distant between incoming flights. An aircraft flying into an airport, can perform a continuous descent or a step down decent. Illustrated in the figure below: From the figure ...


Only top voted, non community-wiki answers of a minimum length are eligible