The patent record splits into three main routes: bleed-air thermal systems that route hot air from the engine compressor to leading edges and nacelles, electrothermal heaters embedded directly in aircraft structures, and hydrophobic or ice-phobic surface coatings that reduce ice adhesion rather than melting it. Bleed-air and electrothermal approaches dominate the dataset by a wide margin, both classified under B64D aircraft equipment, while coating-based approaches under C09D are comparatively rare. Ice detection sensing and control logic runs across all three routes as a supporting technology rather than a standalone cluster.

Filings in this dataset peaked at 22 in 2017 and had fallen to roughly 9 by 2022, with no later year recovering to the earlier level. This pattern is typical of a field where the core architectures — bleed-air ducting, electrothermal heater placement, basic ice detection — were established early, leaving later filers to patent incremental refinements rather than foundational systems. Readers should also account for publication lag: the most recent one to two years in any patent trend are understated because filings take roughly eighteen months to publish, so the apparent decline in the very latest years is partly an artifact of that lag rather than a real drop in activity.

Assignee activity in this dataset is led by established aerospace names including Boeing, Mitsubishi Aircraft, Rohr, Honeywell International, General Electric, and Saab, alongside specialist thermal-systems suppliers like MRA Systems and Kelly Aerospace Thermal Systems. All of the leading assignees show zero filings in the most recent complete year, which tracks the field-wide slowdown rather than indicating any single company has exited the space. Co-filing is limited overall, with only seven recorded co-assignee pairs, the strongest being a nine-family link between two thermal-systems specialists.

The clearest gap is in hydrophobic and ice-phobic coating technology, which accounts for only 4 of 267 families despite appearing directly in the search criteria — a strong signal that durable, aircraft-grade ice-phobic surface treatments remain thinly claimed compared with thermal methods. Ice detection sensor fusion and electrothermal power-management control logic also appear less densely claimed than the core hardware architectures around them. Anyone scoping a new filing should check these branches first, since low record counts there reflect low claim density rather than technical infeasibility.

US11292601B2, assigned to Mitsubishi Aircraft Corporation and published in 2022, claims a bleed-air flow control method that caps bleed air pressure to an anti-icing unit based on the joint relationship between altitude and outside air temperature, using a precooler ahead of the anti-icing unit. Anyone designing a bleed-air anti-icing system with dual altitude- and temperature-linked pressure limiting through a precooler stage needs to check their control logic against this claim structure specifically, rather than against bleed-air anti-icing generally. Systems that regulate bleed air pressure by a single variable, or that omit the precooler heat exchange step, sit further from this claim and may represent a workable design-around.