Legal Interpretations
Jimenez 2014
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U.S. Department of Transportation Federal Aviation Administration Juan Jimenez
Re: Knee Defender
Dear Mr. Jimenez:
NOV 17 201~ This letter responds to your September 8, 2014, request for a legal interpretation regarding use of the Knee Defender, a device designed to allow a passenger on board a cmmnercial aircraft to prevent the seat in front of him or her from reclining. In your letter, you ask (I) whether it is illegal to interfere with "certified components of an aircraft"; (2) whether it would violate FAA. regulations to "attach a device to an aircraft seat that interferes with [the seat's] ability to function as designed"; and (3) whether the knee defender "is a safety issue," and as such should be banned immediately. For the reasons described below, use of the Knee Defender does not violate FAA regulations, unless an individual uses the device against the express instructions of the flight crew.
While many aircraft seats are approved under a Technical Standard Order Authorization, the_ installation of all seats in transport-category aircraft must be approved in accordance with prut 25 of Title 14 of the Code of Federal Regulations (14 CFR). While we have considered how the Kn.ee Defender is used, we have not identified a safety issue associated with inhibiting an aircraft seat's reclining flmction. 1 Furthermore, there is no regulation specifically prohibiting a passenger from interfering with an aircraft seat's reclining function- unlike, for example,§ 121.317(g), which prohibits "tamper[ing] with, disabl[ing], or destroy[ing] any smoke detector installed in any aiiplane lavatory." For these reasons, preventing a commercial airline seat from reclining is not a per se violation of FAA regulations.
This is not to say that a conunercial aircraft passenger may use the Knee Defender, or a similar product, in all instances. In particular, § 91 .11 and related regulations (e.g., § 121.580) strictly prohibit any person from, among other things, "interfer[ing] with a crevvmember in the performance of the crewm.ember's duties aboard an aircraft .. .." In the event that, for pw-poses of maintaining the safety of the airci-aft environment, eithe1· an air earner or an individual crewmember directs that a passenger refrain from using the Knee Defender, any passenger who disregards the air carrier's or creVvru.ember's instructions will be in violation of the FAA's prohibition on interfering with a crewmember. For example, in the event of an emergency, or during taxi, takeoff, and landing, a cre·wmember may ask a passenger using the Knee Defender to remove the device and stow his or her tray table. In 1 Indeed, not all aircraft are equipped with reclining seats. Furthermore, the FAA's certification testing only analyzes aircraft. seats (reclining or otherwise) in an upright position.
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such a case, the passenger's refusal to comply would constitute a violation of our regulations.
This response was prepared by Benjamin Jacobs, an attorney in the International Law, Legislation, and Regulations Division of the Office of the Chief Counsel, and was coordinated with the Aircraft Engineering Division (AIR-100) of the Aircraft Certification Service, the Air Transportation Division (AFS-200) of the Flight Standards Service, and the Department of Transportation's Office of Aviation Enforcement and Proceedings. If you need further assistance, please contact our office at (202) 267-3073 . .... ' -......_ / / ark W. ury "'-" I Assistant Chief Counsel fdrJ International Law, Legislation, and Regulations
Retrieved from ecfr.gov on July 18, 2026.