One aerospace-systems assignee leads the ranked field by a wide margin, with 268 of the 1,456 records in scope. The gap to the rest of the field is steep: fifth place holds 27 records and tenth place holds 16, so the leader’s position is not a narrow edge but a substantial lead. This concentration reflects decades of certified outflow-valve and dual-channel controller designs built into commercial aircraft platforms.

Filing peaked at 59 records in 2017 and has not returned to that level since. Looking at the most recent reliable window, 2021 to 2024, filings moved from 22 to 20, a -9% change that reads as a plateau rather than a sharp decline. Years after 2024 in the dataset are still incomplete because publication typically lags filing by around 18 months, so those figures will rise as more records surface.

Beyond the core aircraft equipment class (B64D, 42.2% of records), a meaningful share of records fall under body-fluid device control (A61M, 10.6%) and non-electric variable control (G05D, 9.1%). Valve and taps (F16K) and separation processes (B01D) each cover a further 6% or so. This spread indicates that outflow valve actuation, differential pressure sensing and control-loop logic are shared building blocks across aviation, medical devices and industrial pressure systems, not exclusive to aircraft cabins.