One assignee leads the ranked field with 83 records, well ahead of the fifth-place figure of 16 and the tenth-place figure of 6. This gap indicates a filer that established broad early coverage of heater-mat and parting-strip designs and has continued to extend it, rather than a field with several evenly matched leaders. The ranking covers 20 companies in total, so it should not be read as a top-50 or top-100 list — it is the full ranked set the underlying data returns.

Filings peaked at 21 in 2018 and the last year-pair that can be treated as complete shows a fall from 10 filings in 2021 to 3 in 2024, a -70% move. Because publication typically lags filing by around 18 months, the 2025 and 2026 counts in this dataset are still filling in and understate real filing activity. The honest reading is a cooling from a 2018 high rather than a field going quiet.

A parting strip is the section of an electrothermal ice protection system that runs along the leading edge and separates the de-icing zones, which shed ice cyclically, from the anti-icing zones, which stay continuously heated. Recent claims — including the representative record in this dataset, US20230166849A1 — move beyond a fixed, uniformly powered strip toward one that adjusts power to targeted heating sections based on sensed airflow direction. That shift from static to airflow-responsive control is one of the more active claim areas in current filings.