All aircraft are developed and certified so as to ensure that their control is easy and well-behaved throughout their operating envelope. Testing to ensure these good handling characteristics assumes that pilots are utilizing typical piloting techniques during routine line operations.
The advancement of technology in today’s modern airplanes has brought us flight directors, autopilots, autothrottles, and flight management systems. All of these devices are designed to reduce the flight crew workload. When used properly, this technology has made significant contributions to flight safety. But technology can include complexity and lead to trust and eventual complacency.
The systems can sometimes do things that the flight crew did not intend for them to do. Industry experts and regulators continue to work together to find the optimal blend of hardware, software, and pilot training to ensure the highest possible level of system performance
Aircraft are designed, tested, and certified based on accepted assumptions of how pilots will operate them, together with various environmental and technical constraints (e.g., gusts, engine failure dynamics). These assumptions drive the regulatory certification requirements and are validated through in-service experience. The certification flight test process examines the entire flight envelope of the aircraft, including that area beyond which the airline pilot normally operates. Examples would be a fully stalled aircraft or airspeed exceeding Vmo. The process even explores how the aircraft could possibly be inappropriately operated; however, the testing assumes fundamental flying skills are known and understood. A primary assumption regarding pilot inputs is that they are based on control inputs that are measured (the result of experience), analyzed, then fine-tuned to achieve a desired result. Exaggerated rates and amounts of control deflection (overcontrolling) may cause an accelerating divergence of flight path control until the input is countered.
Pilots are expected to make control inputs based on desired aircraft reaction. Control deflections at one point in the flight envelope might not be appropriate in another part of the flight envelope. Pilots must have a fundamental understanding of flight dynamics in order to correctly make these choices. They should not make mechanical control deflections and rote reactions to dynamic situations that require an understanding of these flight fundamentals.
Extract from Boeing Document entitled Airplane Upset Recovery dated August 2004