It is a situation many passengers will be familiar with: sitting on an aeroplane, fuelled up and ready to taxi to the runway, and the pilot announces a delay for reasons outside their control. This frustrating experience is one which the system of aircraft flow management in the patent EP1428195 under appeal at the European Patent Office (EPO) in T-497/11 sought to address. In this case, the Board of Appeal had to decide whether the system as claimed provided an inventive step over the prior art, as well as deciding if late filed requests should be admitted. The appellant (patent proprietors) requested that the decision of the Opposition Division to revoke the patent on grounds of, amongst others, exclusion from patentability (Art 52(2) EPC) be set aside and that the patent be maintained.

The system related to processing specified data on aircraft and airports such as speed, fuel, route, weather, runways and airspace availability in order to predict an initial aircraft arrival fix time. A measure is taken of how well operational goals are achieved if the arrival fix times are met (using a goal function). The goal function is then used to identify which arrival fix times can be changed and result in a better achievement of operational goals. This can be achieved, for example, by speeding up or slowing down aircraft so they arrive at the right time for ground services for these aircraft to be available or so that airspace in a particular area is not overloaded.

The appellant's Main Request and Auxiliary Requests 1 and 2 were not admitted because they had deleted a phrase one month before the appeal that had previously been added to overcome an excluded subject matter objection (Art 52(2)(c) EPC). The Board held that there was not a justified reason for reverting back to the claim filed in response to the opposition at this late stage, especially in light of the need to reopen the assessment of a technical nature which had been rendered unnecessary by the amendment.

Auxiliary Requests 3, 4 and 5 were admitted (an examination of clarity was not allowed as the features were already in the claims as granted). Auxiliary Request 6 was not admitted as claim 2 was similar to Auxiliary Request 3 and had the same objection. Auxiliary Request 7 (method claims) was not admitted due to added matter and because there was a change in direction at a very late stage (four higher requests were system claims). The rejections on admissibility could be an indication that the new opposition procedure, which took effect from 1 July 2016 (see, is starting to influence proceedings before the EPO.

The Board assessed which of the features of claim 1 of Auxiliary Request 3 that were not known from the generic prior art in the field of air traffic control were technical. This was necessary because, where the claim comprises a mixture of technical and non-technical features, only the technical features can contribute to the presence of an inventive step (see eg T-641/00).

The appellants argued that claim 1 provided a technical effect of improved safety and reduced fuel consumption, and that the closest prior art was document D1 (WO62234A), not the generic prior art considered by the Opposition Division. They also argued that generic prior art were local solutions with time frames of 20 to 30 minutes whereas the invention was over a timescale of three to five hours, was more complex, used a larger amount of data and this should be interpreted as being included in claims in light of description. However, the Board rejected this because the claims were clear and there was no need to use the description to interpret the claims.

In addition, the Board found that all the differences between claim 1 and the generic prior art could be carried out by a human (eg a flight controller) without involving any further technical means. Thus, these identified differences were regarded as mental acts. For example, the "utilizing of the goal function" to identify which arrival fix times could be changed to better achieve the operational goals could be carried out by a flight controller simply determining which landing sequence would be best for a small number of aircraft. Further, the Board agreed with the respondents (opponents) that the means for communicating information about the updated target arrival times to aircraft so they can change their trajectories did not involve a technical effect (over generic prior art) because it was not mandatory for the pilots to do so.

The Board rejected the appellant's argument in relation to Auxiliary Request 4 that safety and fuel consumption would be reduced because they considered that it was not apparent how the invariant position of the aircraft could be used to determine the flow of aircraft. The Board held that claim 1 of Auxiliary Requests 4 and 5 merely defined the automation of a mental act by known means. Since none of the admitted requests were allowable, the Board dismissed the appeal.

This case shows that you must carefully justify the reasons for any late filed requests. For example, a change of representative is not good enough, but addressing a new objection raised by the Board might be. Further, you cannot rely on interpretation of claims (Art 69 EPC) to add additional limitations to the claims when the claims are clear. Amendments that require consideration of an objection that was previously overcome may not be allowed. In addition, changing direction at a late stage (eg by filing method claims when higher requests are all system claims or vice versa) may not be allowable as the EPO is seeking to speed up procedures and does not take kindly to an applicant going down a completely different route. Due to the continuing efforts of the EPO to progress oppositions and appeals expeditiously, this case provides evidence that it is necessary, where possible, to submit facts, evidence or requests at the beginning of the procedure, or at least at the earliest opportunity.

In addition, it is necessary to carefully assess whether your claimed features could be carried out mentally by a human using only known means (eg a generic computer). If this is the case, then it is worthwhile considering providing a clear further technical step.