Born: United States of America
Primarily active in: United States of America

1942-2025

Roger Hoh, Handling Qualities Pioneer

Hoh was born on July 2, 1942, and earned his Bachelor of Science in Aerospace Engineering degree from California State Polytechnic University in Pomona, California, in 1964. This was followed by a Master of Science in Aerospace Engineering in 1968 from the University of Southern California in Los Angeles, where he also contributed to the Apollo space program.

From 1968 to 1988, Hoh worked as a Senior Research Engineer at Systems Technology, Inc. (STI) in Hawthorne, California. Hoh’s early research on outside cueing effects in rotorcraft handling qualities and his key role in developing single-pilot instrument flight rules (IFR) requirements for the US Federal Aviation Administration (FAA) were instrumental in shaping aviation standards. His insights continue to be referenced by engineers and pilots.

At STI, he was a project engineer and worked to develop the foundational handling qualities specification for military helicopters (ADS-33E-PRF), as well as the requisite background information and user guide. He was also the principal investigator and lead author of the US military specifications MIL-STD-1797, “Flying Qualities of Piloted Aircraft.” Through his work, Hoh defined the criteria for acceptable handling qualities that have endured for decades. His groundbreaking work on the Bandwidth/Phase Delay criteria remains one of the most vital tools in evaluating flying qualities.

Hoh conducted numerous handling qualities studies and flight control system developments for fixed- and rotary-wing aircraft.

Following his 20-year career at STI, Hoh founded and served as president of Hoh Aeronautics, Inc. — based in Lomita and Grass Valley, California — until his death. There, he continued the development of the ADS-33 rotorcraft handling qualities specification, including simulations and variable stability flight testing to develop methods to implement and enhance limited authority flight control systems for helicopters. He created many of the rotorcraft handling qualities concepts now in common use, including mission task elements (MTEs), useable cue environment (UCE), response types and bandwidth criterion.

Hoh Aeronautics also worked to develop, flight test and certify HeliSAS, a lightweight, low-cost stability augmentation system and autopilot for helicopters and obtain supplemental type certificates (STCs) for Robinson, Bell and Eurocopter/Airbus models. Hoh sold the rights for HeliSAS in the 1990s; it’s now supported and marketed by Genesys Aerosystems, a Moog Company.

Hoh supported the Army/NASA Rotorcraft Division at NASA Ames Research Center on the development of a digital flight control system for the CH-47F, an extension of earlier work to develop improved control laws for the CH-47E in cooperation with Boeing. He also assisted the Army with a flight control system upgrade to the AH-64 Apache and the development of control laws for RAH-66 Comanche.

Hoh also developed, flight tested and certified symbology and guidance laws that supported CAT III low-visibility takeoff head up displays (HUDs) for two manufacturers for the Boeing 737.

During his long career, Hoh performed as an engineering test pilot in support of numerous flying qualities experiments and new product development, including ground-based and in‑flight (variable stability) simulations of conventional and vertical takeoff and landing (CTOL and VTOL) fixed‑wing aircraft and rotorcraft. He also served as a test pilot on prototype and modified general aviation aircraft. Hoh held a US Federal Aviation Administration (FAA) Airline Transport Pilot (ATP) rating, was a commercially rated pilot for rotorcraft, held instrument and instrument instructor ratings for fixed wing-aircraft, and was type rated in the Boeing 737.

Hoh was an FAA Designated Engineering Representative (DER) as a flight test pilot, flight test analyst, and for systems and equipment for FAA regulations Parts 23, 25 and 27. He was an experimental test pilot and a longstanding member of the Society of Experimental Test Pilots (SETP), flying a variety of aircraft to improve airworthiness and control systems.

A respected educator, Hoh taught numerous technical courses and authored many reports and papers. His lectures at the US Air Force Test Pilot School were highly regarded, and his expertise contributed to countless simulations and flight tests. Over his career, he developed flight control systems, visual guidance aids, stability augmentation systems/autopilots and pilot training tools.

STI posted on LinkedIn that, at the company, “Roger spent 20 years driving innovation that saved lives. Later, as the founder of Hoh Aeronautics, Inc., he continued to collaborate with STI. His legacy will inspire generations to come.”

VFS Fellow Nick Lappos commented, “Roger was one of the chief architects of the revolution in the science of handling qualities, a revolution that every pilot today takes benefit of. Roger saw our craft with tremendous clarity, and he conducted experiments that produced clear and important insights into how the future would be. We are today living in the future that Roger helped create.”

VFS Fellow Dr. Mark Tischler wrote “Roger had many innovations and firsts in the ADS-33 rotorcraft HQ [handling qualities] criteria — his shift from the time domain specs of the old MIL-H-8501 to the frequency domain (as in fixed-wing), integration of the useable cue environment with associated response types and HQ boundaries, and the concepts of MTEs. All were firsts and made a huge impact. He had a special combination of skills as both an excellent researcher and experienced fixed-wing and rotorcraft pilot.”

Roger Henry Hoh, age 82, of Grass Valley, California passed away on Saturday, March 1, 2025. A true pioneer in the field of flight controls and handling qualities for both fixed-wing and rotary-wing aircraft, Roger Hoh’s contributions continue to shape aviation today.
https://www.linkedin.com/in/roger-hoh-a4441522

Society Updates: Vertiflite, May/June 2025