CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 776/21 – Public prior disclosure by the proprietor before the filing date - Priority not valid

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The patent relates to a split winglet for an aircraft wing.

Various wing tip devices, i.e. winglets and geometries are known.

The split winglet disclosed in the patent includes separate extensions above and below the wing chord plane. The split winglet includes an upward sloping element similar to an existing winglet and a downward canted element (ventral fin). The ventral fin counters vortices generated by interactions between the wingtip and the lower wing surface.

Picture taken at the exhibition

Brief outline of the case

Before the OD the proprietor accepted that the effective date of claim 1 as granted was the filing date.

Although the patent claimed the priority of a US provisional the information disclosed in the latter was rather scarce and only the basic concept of a split winglet was disclosed but none according to the one actually claimed.

The OD rejected the opposition and the opponent appealed.

The board decided that the claimed split winglet was novel but lacked inventive step with respect of the devices disclosed by the proprietor at an exhibition organised by the National Business Aircraft Association (NBAA) prior to the filing date of the application.

The patent was revoked.

Public prior use

The prior use by the proprietor was resumed under D4=blended split winglet displayed at the NBAA 2011 exhibition with the following documents as evidence:

D4a: FLIGHT NBAA: Split winglets latest Evolution from Aviation Partners from Flight 2011 -10-13 (retrieved on 2018-12-12)

D4b: FLIGHT NBAA 2011: Convention Photo Gallery 2011 (retrieved on 2018-02-23)

D4b1: FLIGHT NBAA 2011: Convention Photo Gallery 2011 with improved explanations and resolution

D4c: Images 1-7: Photos from Winglets (prior use)

D4d: Aviation Partners Unveils the Shapes of the Future, 09-10-2011, Aviation Partners Inc

D4e: API displaying trio of blended winglets here, Mark Huber, 10-12-2011

D4e1: NBAA 2011 Tuesday Headlines, Chad Trautvetter, 10-10-2011, YouTube Video submitted also by DVD

D4f: Aviation Partners unveils new designs, 10-11 -2011, Aviation Partners Inc

D4g: News & Events: Aviation Partners Inc displayed new winglet shape at NBAA, 18-10-2011

D4h: Aviation Partners @ NBAA 2100, Robert MacKenzie, 10-10-2011, YouTube Video submitted also by DVD

D4i: FlightBlogger – Aviation Partners’ Blended Split Winglet – October 2011, Jan Ostrower, 17-10-2011, YouTube Video submitted also by DVD

D4j: NBAA 2011 – Blended Split Winglet – LVCC – Las Vegas, NV, photo from

D4k: Aviation Partners Sets World Record -Without Winglets, 10-10-2011.

The above picture stems from the documents summarised in D4.

Lack of inventive step

It was not disputed that the blended split winglet (documents D4A-D4K as evidence) was presented at the NBAA 2011 exhibition at a date which is before the effective date of filing of the patent application.

The Board followed the OD and the proprietor’s view that the blended split winglet on display is a model. Although the model is representative of a wing tip geometry, none of the videos or pictures related (see documents D4A-D4K) show an attachment end shaped to attach to a wing.

An attachment end shaped to attach to a swept and tapered wing with a leading edge (Feature 2.1) was therefore not anticipated by the blended split winglet presented at the NBAA 2011 exhibition.

The board held that subject-matter of claim 1 differs from the blended split winglet presented at the NBAA 2011 exhibition in that the wing tip comprises an attachment end shaped to attach to a wing.

The technical effect of the identified difference is to enable the attachment of the wing tip to the wing. The problem to be solved may be regarded as to provide attachment means suitable to attach the wing tip to a wing.

Starting from the blended split winglet, it is obvious for the skilled person to add an attachment end shaped to attach to a wing. Indeed, winglets are meant to be attached to a wing. The skilled person would therefore provide an attachment end at the root of the winglet.

The proprietor was of the opinion that the inventive step argumentation is based on hindsight. In its view it is not obvious to add an attachment end to the blended split winglet displayed at the NBAA 2011 exhibition such as to attach to a wing. The winglet may be integrated in the wing.

The Board did not agree. Whilst it is accepted that a winglet integrally formed with a wing is a known possibility which would not require an attachment end, it is well known in the art that a winglet might instead be attached to a wing. Such alternative would be of obvious implementation on the blended split winglet for the skilled person. This would actually be the most straight forward alternative as the blended split winglet was displayed as such and not with a wing.


The case is interesting for two aspects:

  1. The US provisional was not allowing the claim as granted to benefit from its priority.
  2. The proprietor himself disclosed the invention in a public exhibition before the filing date of the Euro-PCT application.

In the US such “mistakes” do not necessarily lead to deleterious consequences, but they can be fatal in Europe.

The US provisional led also to a further Euro-PCT application = EP 2 718 183 relating to the second aspect disclosed in said US provisional relating to a split spiroid exhibiting an enclosed loop. This device was apparently not disclosed at the NBAA. No opposition was filed against this second patent.

It is, to my knowledge, not to be seen on actual planes, whereas split winglets are used for instance on recent types of Boeing 737/800.

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