AMI Industries, Inc. v Martin Baker Aircraft Company Ltd [2026] EWHC 1027 (Pat)
AMI’s patent was to an aircraft ejection seat headrest intended to reduce head and neck injuries caused to pilots during ejection. The dynamics of an ejection initially force the pilot’s head down towards their chest, then as they emerge from the cockpit the force of the windblast immediately slams their head back against the headrest.
Martin-Baker’s ejection seats include an inflatable structure behind the headrest which, upon ejection, deploys forward to a fixed position. AMI said the patent covered such an arrangement, including as a matter of the doctrine of equivalents. Martin-Baker argued the patent did not cover such an arrangement, but that if it did then the patent lacked priority, novelty and inventive step. Martin-Baker also advanced a breadth of claim insufficiency attack. The central issues were therefore construction and infringement, on which Mellor J sided with Martin-Baker and held the patent valid but not infringed.
As well as conventional construction, novelty and obviousness points, the judgment contains legal analysis and application of the laws of priority, breadth of claim insufficiency, and infringement by the doctrine of equivalents.
Mark Vanhegan KC and Adam Gamsa appeared for the Claimant, AMI. Iain Purvis KC and Christopher Hall appeared for the Defendant, Martin Baker.