The ranked leaders in this 39-record dataset are concentrated at the top: the top five assignees together account for 22 records, or 56.4% of everything in scope, and the leading assignee alone holds seven. Below the top ten, which together reach 82.1%, filing activity thins into a long tail of assignees with one or two records each, including universities and individual inventors. This is a field with a clear leading cluster but no single dominant monopolist.

Filing peaked at three records in 2021, the high point across the 2015-2026 window, and had fallen to one record by 2024 — a -67% change over that three-year span. Because patent publication typically lags actual filing by around 18 months, the apparent low counts in 2025 and 2026 are very likely incomplete rather than evidence of a further decline. The safest read is a single peak year followed by a plateau, not a confirmed downward trend.

The dominant class is G01N, material analysis and testing, present on 56.4% of the 39 records, reflecting how much of the inventive activity sits in sensing and diagnostic method rather than structure. G01L (force and pressure measurement) and G01M (testing machine and structure balance) follow at 25.6% and 23.1%. Airframe-specific classes B64C and B64D, along with vibration-sensing class G01H, each sit around 15-20%, and ground-installation class B64F is the smallest at 12.8%.

US5905260A, QinetiQ's triboluminescent damage sensor patent originally filed via PCT in 1996 and granted in 1999, claims a sensor design using triboluminescent material coupled to detectors via light-guiding fibres or layers, embedded in or mounted on a structure such as an aircraft wing, to detect impact damage through light emission. It is one of the most-cited records in this set at 36 citations. Its claims are specific to that light-emission detection mechanism, so approaches based on strain gauges, fibre Bragg gratings, piezoelectric sensing or acoustic emission are not directly blocked by it, though anyone using triboluminescent materials for damage detection needs to check its claim scope carefully.

The clearest gap by class share is ground-installation and retrofit infrastructure (B64F), covering just 12.8% of the 39 records against 56.4% for core sensing-method claims under G01N. Co-filing is also sparse, with only five co-assignee pairs in the whole dataset, suggesting little joint development activity and room for partnerships between sensor developers and airframers. Given the thin tail below the top ten assignees, there is also room for new entrants to stake out specific sensing modalities, such as combined vibration-and-solid-state approaches (G01H and H10N together sit near 20% each), before the leading cluster extends further into them.