View source for Deicing boot

[[File:Horizon Air Q400 deicing boot.JPG|thumb|The black rubber deicing boot on the wing of a [[Bombardier Dash 8]] Q400 passenger aircraft is inflated with air, producing ridges to crack and dislodge any accumulated ice.]]
[[File:Deicer (PSF).png|thumb|Operation of deicing boots]]
[[File:Leading edge of Beechcraft 350ER (2).jpg|thumb|De-icing rubber boots on the wing leading edge of a [[Beechcraft Super King Air|Beechcraft 350]]]]

A '''deicing boot''' is a type of [[ice protection system]] installed on [[aircraft]] surfaces to permit a mechanical [[deicing]] in flight. Such boots are generally installed on the leading edges of wings and [[Flight control surfaces|control surfaces]] (e.g. [[Horizontal stabilizer|horizontal]] and [[vertical stabilizer]]) as these areas are most likely to accumulate ice which could severely affect the aircraft's performance.

== Design ==
A deicing boot consists of a thick rubber membrane that is installed over the surface to be deiced. As [[atmospheric icing]] occurs and ice builds up, a pneumatic system inflates the boot with compressed air. This expansion in size cracks any ice that has accumulated, and this ice is blown away into the airflow. The boots are then deflated to return the wing or surface to its optimal shape.

Boots require proper care. Holes in the boot may create air leaks that will decrease the effectiveness of the boots. As such, boots must be carefully inspected before each flight and any holes or cuts must be patched.

== History ==
Deicing boots were invented by the [[Goodrich Corporation|B.F. Goodrich Corporation]] in about 1929–1930 in [[Akron, Ohio]]. The work was begun by retired Ph.D chemist, [[William C. Geer]].  In its quest to develop deicing boots, the company built a large indoor facility in Akron to replicate bad weather and icing on aircraft wings.<ref>{{cite magazine |url = https://books.google.com/books?id=u-IDAAAAMBAJ&dq=Popular+Mechanics+1931+curtiss&pg=PA234 |title = Artificial Blizzards Help To Protect Planes |date =  February 1931 |magazine = Popular Mechanics |page = 234 |via = Google Books }} Illustration of blizzard machine and how de-icing boots work.</ref><ref>{{cite magazine |url = https://books.google.com/books?id=XygDAAAAMBAJ&dq=Popular+Science+1931+plane&pg=PA28 |title = Overshoes For Planes End Ice Danger |date = November 1931 |magazine = Popular Science |page = 28 |via = Google Books }}</ref><ref>{{cite book |first = William M. |last = Leary |title = We Freeze to Please: A History of NASA's Icing Research Tunnel and the Quest for Flight Safety |date = 2002 |location = Washington, DC |publisher = National Aeronautics and Space Administration |page = 10 |oclc = 49558649 }}</ref>

== Alternatives ==
The use of deicing boots may enable an aircraft to be certified for flight into known icing conditions. However, they may not be sufficient to handle extremely severe icing, where ice can accumulate faster than the boots can shed it, or it accumulates on non-booted surfaces to the point where there is a dangerous loss of lift or control, or increase in weight.

Deicing boots are most commonly seen on medium-sized airliners and utility aircraft. Larger airliners and military jets tend to use heating systems within the wing, keeping it constantly warm and preventing ice from forming. Sources of heat include:
* [[Bleed air]] systems use high-temperature, compressed air from the engine compressor sections, and duct it towards the sections to be de-iced where it delivers its heat before being released into the airflow.
* Electrothermal systems pass electric current through [[resistive]] parts, usually the leading edges themselves. These systems require substantial electrical power and are generally used on large aircraft, such as the [[Boeing 787 Dreamliner|787]]. Resistive deicing may also be applied to propeller and helicopter rotor blades.

== Ice bridging ==
'Ice bridging' is the theory that activating deicing boots early may lead to a condition where slushy ice is pushed into a hollow shell around the inflated boot, then freezes in place. This shell can then no longer be dislodged by any further operation of the boot. Bridging was described by the aviation writer [[Ernest K. Gann|Ernest Gann]] in his memoir ''[[Fate Is the Hunter]]''.

The bridging theory is now disputed. In 2008 the [[National Transportation Safety Board|NTSB]] issued an alert<ref>{{Cite web |title = Activate Leading Edge Deice Boots As Soon as Airplane Enters Icing Conditions |publisher = [[National Transportation Safety Board]] |id = SA-014 |url = https://www.ntsb.gov/safety/safety-alerts/Documents/SA_014.pdf |archive-url = https://web.archive.org/web/20210427044612/https://www.ntsb.gov/safety/safety-alerts/Documents/SA_014.pdf |archive-date = 27 April 2021 }}</ref> that pilots should, "activate boots as soon as the airplane enters icing conditions".<ref>{{Cite news |title = De-icing:NTSB: 'ice bridging' is a myth |date = 28 January 2009 |first = Matt |last = Thurber |work = AIN online |url = https://www.ainonline.com/aviation-news/aviation-international-news/2009-01-28/de-icingntsb-ice-bridging-myth }}</ref> Their claim was that bridging was "extremely rare, if it exists at all" and that there were no instances where it had led to an accident. Unwarranted fear of ice bridging contributed to the fatal crash of [[Comair Flight 3272]].

== References ==
{{Reflist}}

== External links ==
* [http://www.tc.faa.gov/its/worldpac/techrpt/ar06-48.pdf Investigations of Performance of Pneumatic Deicing Boots, Surface Ice Detectors, and Scaling of Intercycle Ice], [[FAA]] report, November 2006
* [http://www.avweb.com/avwebflash/news/NTSBWarnsPilotsToUseDeIcingBootsEarly_199451-1.html?CMP=OTC-RSS NTSB Warns Pilots To Use De-Icing Boots Early, AVWeb,  Dec 2008] {{Webarchive|url=https://web.archive.org/web/20160303183705/http://www.avweb.com/avwebflash/news/NTSBWarnsPilotsToUseDeIcingBootsEarly_199451-1.html?CMP=OTC-RSS |date=2016-03-03 }}

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[[Category:Aircraft Icing Protection Systems]] [[Category:Pneumatic Deicing]] [[Category:Anti-Ice Systems]]
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[[Category:In-Flight Icing]] [[Category:Aircraft Safety Equipment]] [[Category:Aircraft Wing Protection]]
[[Category:Aircraft Tail Deicing]] [[Category:Surface Contamination]] [[Category:Aircraft Systems]]
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[[Category:Cold Weather Aviation]] [[Category:Deicing System Failures]] [[Category:Icing Certification]]
[[Category:Flight Hazard Mitigation]] [[Category:Airframe Protection]] [[Category:Pitot Tube Deicing]]
[[Category:Leading Edge Protection]] [[Category:TKS Systems]] [[Category:Aircraft Fluids and Chemicals]]
[[Category:Aviation Meteorology]] [[Category:Icing Sensor Systems]] [[Category:Aircraft System Redundancy]]
[[Category:Crew Procedures in Icing]] [[Category:Preflight Deicing]] [[Category:Air Safety Procedures]]
[[Category:Aircraft Risk Factors]] [[Category:Accident Causal Factors]] [[Category:Post-Crash Investigations]]
[[Category:Flight Risk Management]] [[Category:Propeller Deicing]] [[Category:Aircraft Electrical Systems]]
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[[Category:Wing Aerodynamics]]