Spoiler (aeronautics)

2025-06-25T12:26:19Z

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{{Short description|Device for reducing lift and increasing drag on aircraft wings}}
[[File:Lift dumperinnerworkingsa320.jpg|thumb|right|The inner workings of spoilers in lift dump deployment during the landing of an [[Airbus A320]]]]
[[File:Air Jamaica A321 landing spoilers opened.jpg|thumb|right|A spoiler (the parts of the wing that are raised up) during the landing of an [[Airbus A321]]]]
[[File:Boeing 767-323ER spoilers on descent to POS, AAL 1167, 11-29-12.jpg|thumb|right|The right wing of a [[Boeing 767-300ER]] during descent with spoilers partially deployed]]
[[File:Qantas Boeing 737-800 spoiler deployed for descent.jpg|thumb|right|Spoilers deployed to slow down for descent on a Qantas [[Boeing 737-800]]]]

In [[aeronautics]], a '''spoiler''' (sometimes called a '''lift spoiler''' or '''lift dumper''') is a device which increases the [[Drag (physics)|drag]] and decreases the [[lift (force)|lift]] of an [[airfoil]] in a controlled way. Most often, spoilers are hinged plates on the top surface of a wing that can be extended upward into the airflow to ''spoil'' the streamline flow. By so doing, the spoiler creates a controlled [[Stall (flight)|stall]] over the portion of the wing behind it, greatly reducing the lift of that wing section.

Spoilers differ from [[air brake (aeronautics)|airbrakes]] in that airbrakes are designed to increase drag without disrupting the lift distribution across the wing span, while spoilers disrupt the lift distribution as well as increasing drag. However, flight spoilers are routinely referred to as "speed brakes" on transport aircraft by pilots and manufacturers, despite significantly reducing lift.<ref>{{Cite web |date=2023-09-28 |title=A320 SPEEDBRAKE LEVER - AviationHunt |url=https://www.aviationhunt.com/a320-speedbrake-lever/ |access-date=2025-02-17 |language=en-US}}</ref>

Spoilers fall into two categories: those that are deployed at controlled angles during flight to increase descent rate ("flight spoilers") or control roll ("[[spoileron]]s"), and those that are fully deployed immediately on landing to greatly reduce lift and increase drag ("ground spoilers"). In modern fly-by-wire aircraft, the same set of control surfaces can serve both functions ("multifunction spoilers").

Spoilers were used by most [[Glider (sailplane)|gliders]] (sailplanes) until the 1960s to control their rate of descent and thus achieve a controlled landing. Since then, spoilers on gliders have almost entirely been replaced by airbrakes, usually of the [[Schempp-Hirth]] type. Spoilers and airbrakes enable the glide angle to be altered during the approach while leaving the speed unchanged.

[[Airliner]]s are commonly fitted with spoilers. Spoilers are used to increase descent rate without increasing speed. Spoilers may also be differentially operated for roll control as spoilerons in place of [[ailerons]]; Martin Aircraft was the first company to develop such spoilers in 1948.<ref>[https://books.google.com/books?id=QCgDAAAAMBAJ&dq=popular+science+1930&pg=PA91 "Spoilers Aid Aileron Control."] ''Popular Science'', August 1948, p. 91.</ref> On [[landing]] the spoilers are usually fully deployed to help slow the aircraft: the increase in [[form drag]] created by the spoilers provides a braking effect. The spoilers also cause a significant loss of lift so that there is more weight acting on the landing gear, allowing more braking to be used without skidding.

In air-cooled [[piston engine]] aircraft, spoilers may be needed to avoid [[Shock cooling (engines)|shock cooling]] the engines. In a descent without spoilers, air speed is increased and the engine will be at low power, producing less heat than normal. The engine may cool too rapidly, resulting in stuck valves, cracked cylinders or other problems. Spoilers alleviate the situation by allowing the aircraft to descend at a desired rate while letting the engine run at a power setting that keeps it from cooling too quickly (especially true for [[turbocharged]] piston engines, which generate higher temperatures than [[normally aspirated]] engines).

==Spoiler controls==
Spoiler controls can be used for roll control (outboard or mid-span spoilers) or descent control (inboard spoilers).

Some aircraft use spoilers in combination with or in lieu of [[aileron]]s for roll control, primarily to reduce [[adverse yaw]] when rudder input is limited by higher speeds. For such spoilers the term [[spoileron]] has been coined. In the case of a spoileron, in order for it to be used as a control surface, it is raised on one wing only, thus decreasing lift and increasing drag, causing roll and yaw. Eliminating dedicated ailerons also avoids the problem of [[control reversal]] and allows [[flap (aeronautics)|flaps]] to occupy a greater portion of the wing trailing edge.

Almost all modern jet airliners are fitted with inboard lift spoilers which are used together during descent to increase the rate of descent and control speed. Some aircraft use lift spoilers on landing approach to control descent without changing the aircraft's attitude.

One jet airliner not fitted with lift spoilers was the [[Douglas DC-8]] which used reverse thrust in flight on the two inboard engines to control descent speed (however the aircraft was fitted with lift dumpers). The [[Lockheed Tristar]] was fitted with a system called ''Direct Lift Control'' that used the spoilers on landing approach to control descent.

[[Airbus]] aircraft with [[fly-by-wire]] control utilise wide-span spoilers for descent control, spoilerons, gust alleviation, and lift dumpers. Especially on landing approach, the full width of spoilers can be seen controlling the aircraft's descent rate and bank.

==Ground spoilers<span class="anchor" id="Lift dumpers"></span>==
Ground spoilers, sometimes called lift dumpers informally, are a special type of spoiler designed to reduce wing lift on landing, differentiated from flight spoilers by having only two positions: deployed and retracted. The spoilers have three main functions: increasing the weight acting the [[landing gear]] for maximum braking effect, increasing [[form drag]], and preventing aircraft "bounce" on landing.<ref>{{Cite web |date=2023-09-21 |title=ATA 27: Airbus A320 (Technical Notes) - AviationHunt |url=https://www.aviationhunt.com/airbus-a320-ata-27/ |access-date=2025-02-19 |language=en-US}}</ref>

Ground spoilers usually deploy automatically on touch down, with the flight spoilers also raised to increase the effect.

Virtually all modern jet aircraft are fitted with ground spoilers. The [[British Aerospace 146]] is fitted with particularly wide-span spoilers to generate additional drag and make [[reverse thrust]] unnecessary.

A number of accidents have been caused either by inadvertently deploying ground spoilers on landing approach, or forgetting to set them to "automatic".

==Incidents and accidents==
* [[Air Canada Flight 621]] – Premature deployment of the spoilers at low altitude contributed to this crash in [[Toronto]] on 5 July 1970.
*[[United Airlines Flight 553]] – Forgetting to deactivate the spoilers contributed to crash at [[Chicago Midway International Airport]] on 8 December 1972.
*[[Loftleiðir]] Icelandic Airlines Flight 509  – Deployment of lift dumpers while attempting to arm them 40 feet above the runway caused this accident at [[John F. Kennedy International Airport]] on 23 June 1973.<ref>{{cite web|title=Accident report AAR-73-20|url=http://www.airdisaster.com/reports/ntsb/AAR73-20.pdf|publisher=NTSB|date=5 December 1973|access-date=2012-11-21|archive-url=https://web.archive.org/web/20121004115036/http://www.airdisaster.com/reports/ntsb/AAR73-20.pdf|archive-date=4 October 2012|url-status=usurped|df=dmy-all}}</ref>
*[[American Airlines Flight 965]] – Forgetting to deactivate the spoilers while climbing to avoid a mountain contributed to this crash on 20 December 1995.
*[[American Airlines Flight 1420]] – Forgetting to deploy the spoilers contributed to this crash at [[Little Rock National Airport]] on 1 June 1999.
*[[Atlantic Airways Flight 670]] – The spoilers did not deploy during landing on a fairly short wet runway, causing overrun and falling over a cliff, on 10 October 2006.
*[[TAM Airlines Flight 3054]] – This [[Airbus A320 family|Airbus A320]]'s pilots were aware of their deactivated starboard engine #2 thrust reverser,<ref>{{cite web|title=Full cockpit-voice transcript of TAM A320 reveals clues to crash|url=http://www.flightglobal.com/articles/2007/08/02/215869/full-cockpit-voice-transcript-of-tam-a320-reveals-clues-to-crash.html|publisher=flightglobal.com|access-date=2008-03-19}}</ref> and so apparently did not attempt to use it to brake when attempting to land at [[Congonhas-São Paulo International Airport|São Paulo's Congonhas Airport]] on 17 July 2007; under one theory of the cause, they used an old procedure, which reduced the required runway length for landing but was superseded because it invited pilot error, which required them to leave the engine in idle rather than reverse thrust, and mistakenly left the engine at full power.<ref>[http://www.cenipa.aer.mil.br/cenipa/paginas/relatorios/pdf/3054ing.pdf Final Report] (PDF), [[Aeronautical Accidents Investigation and Prevention Center]], October 27, 2009.</ref> The plane's spoilers may have been their only method of braking at speed. The plane slid off the runway, over a major highway, and ploughed into a warehouse, killing all 186 on board as well as several on the ground. It was [[Brazil]]'s worst aviation disaster.<ref>{{cite web|title=Brazil pilots' last words aired|url=http://news.bbc.co.uk/2/hi/americas/6926679.stm|publisher=[[BBC]]|access-date=2008-03-19 | date=1 August 2007}}</ref>
*[[2023 Elmina Beechcraft 390 crash]] – Inadvertent deployment of spoilers of a [[Beechcraft Premier I|Beechcraft 390 Premier I]] business jet while attempting to arm them before landing, resulting in a sudden loss of lift and subsequent crash in [[Sungai Buloh]], [[Selangor]], [[Malaysia]], on 17 August 2023.<ref>{{Cite web |title=Elmina Crash Report Aircraft Accident Final Report A05/23 |url=https://www.mot.gov.my/en/aviation/reports/a05-23|access-date=2024-08-16 |website=Ministry of Transportation|language=en}}</ref>

==See also==
*[[Air brake (aircraft)]]

==References==
{{Commons category|Spoilers (aircraft wings)}}
{{more citations needed|date=January 2009}}
{{Reflist}}

{{Aircraft components}}
{{Authority control}}

[[Category:Aircraft controls|Spoiler]]
[[Category:Aircraft wing components]]

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Spoiler (aeronautics)