The Effects of Using an Angle of Attack System on Pilot Performance and Workload during Selected Phases of Flight

In-flight loss of control (LoC-I) is the number one fatal accident category for light airplanes. The most common type of LoC-I accident involves a stall/spin and inadequate airspeed management and is frequently cited as a causal factor. An aircraft stalls when the critical angle of attack is exceeded and this may occur at any indicated airspeed, hence the use of airspeed as an indication to the proximity to stall is unreliable. This is of particular importance during the take-off, approach and landing where stall margins are reduced. Military aircraft commonly use angle of attack (AoA) devices to indicate proximity to the stall and these have been in continuous use for almost 60 years. More recently, with the simplification of light airplane design approval requirements, an increasing number of AoA designs are appearing on the market, installed in light airplanes to complement airspeed indication and stall warning systems, to notify pilots of proximity to the stall. This paper reviews a selection of current types of AoA devices and presents the preliminary results of practical flight testing and flight simulation experiments to investigate the effects of using an AoA on pilot performance and workload during selected phases of flight. The results have implications for the operational use of current AoA devices and future AoA design.