The ranking is led by one assignee with 34 records, with the fifth-placed holder at 16 and the tenth at 9, out of 100 ranked assignees in this dataset. The top five combined hold 34.8% of the 356 records in scope, and the top ten hold 51.4%, so roughly half of all filing activity sits with a small group of repeat filers. Beyond that group there is a long tail of single- or low-filing entrants, which is typical for a field organised around a handful of aerospace primes and engine specialists rather than a broad supplier base.

Filings peaked at 42 in 2020 after rising from 23 in 2017, then declined across the most recently complete span, moving from 27 in 2021 to 22 in 2024, a 19% drop. That is a real cooling from the 2020 peak rather than a rounding effect. Figures for 2025 and 2026 are still filling in, because publication lags filing by roughly 18 months, so it would be a mistake to read the most recent two data points as evidence the trend has kept falling.

Aircraft equipment (B64D) is the largest single class, covering 22.5% of the 356 records in scope, followed by printed circuits and assemblies (H05K) at 13.2%. Gas-turbine plants (F02C), aeroplanes and helicopters (B64C), and batteries and fuel cells (H01M) each sit around 6.7-7.6%, with control and regulating systems (G05B) and related classes each under 6%. Because a single record can carry several IPC classes, these shares add up to more than 100% and should be read as claim density per class, not as a breakdown of the full record set.

US7633980B1, assigned to the US Department of Energy and granted in 2009, claims a phase-change cooling method that uses a split two-flow design to regulate temperature above the phase-change material's fusion point for intermittently operated, burst-mode heat loads including flight avionics. It blocks designs that use this specific split-flow phase-change architecture for burst-mode cooling of comparable heat loads. It does not cover steady-state cooling, single-flow phase-change designs, or non-phase-change thermal approaches, all of which remain open alternative routes.

The composition data points to control and regulating systems (G05B, 5.9% of records), checking/attendance-type devices (G07C, 6.5%) and the H10W class (6.2%) as comparatively under-claimed relative to the 22.5% held by aircraft equipment and 13.2% held by printed circuit assemblies. These branches still carry double-digit record counts, so they are active but not yet dense. A first claim there is more defensible if it targets control-logic architecture, such as sensor-triggered load-shedding above a defined temperature threshold, rather than the cooling hardware itself.