A CASE STUDY IN THE DESIGN AND TESTING OF HANDS-ON CONTROLS - THE LONGBOW APACHE GRIP DEVELOPMENT PROCESS

The US Army/McDonnell Douglas Helicopter Systems (MDHS) AH-64D Longbow Apache attack helicopter is equipped with an integrated controls and displays suite providing the pilot and copilot-gunner with the ability to control the advanced avionics equipment and weapon systems incorporated in the aircraft. The new AH-64D crew station controls and displays suite includes four grips which provide hands-on and eyes-out controls: the cyclic grip, collective grip, left-hand targeting grip, and right-hand targeting grip. The development of these four grips represents a recent case study in the design and user testing of hands-on controls which are tailored for the demanding missions performed by attack and scout helicopter pilots. This technical report summarizes the design process for the Longbow Apache grips, including: the initial conceptual designs, switch function allocations, clay model development, user pilot testing, anthropometric accommodation evaluations, three-dimensional computer modeling, laser-stereolithography model development, pilot-in-the-loop full-mission flight simulator evaluations, production qualification, and flight testing. Detailed design and evaluation criteria are provided, such as the use of standard switch locations to improve transfer-of-training, the use of shape-coded switch caps to maximize eyes-out operations, and the necessary switch separations required to preclude inadvertent selections. In comparison to the AH-64A, the total number of hands-on switch functions has nearly doubled for the AH-64D, and this presented significant design challenges to ensure effective use of the grips during a wide range of mission scenarios. The authors provide evidence to support their claim that the number of hands-on switch functions is not a valid measure of pilot workload, and they counter controversial opposing viewpoints expressed by previous researchers in this regard. Also included is a description of the multi-media pilot training program for the use of the available hands-on controls, and the lessons learned from flight testing the AH-64D grips. The authors conclude with a discussion of the impact of new and emerging technologies (artificial intelligence, cognitive decision aiding, pilot-centered automation, helmet tracking cursors, and voice recognition systems) on the design of future hands-on controls for the next generation of combat aircraft.