Flight envelope protection
The Flight Envelope Protection (flight area boundary protection) is an independent protection that works in the background against dangerous exceeding of the flight envelope (flight area boundary). A computer checks the pilot's control commands before they are implemented.
General
Thanks to the "Flight Envelope Protection", the aircraft does not end up in a flight area in which the aircraft would be endangered, even if the pilot reacts rashly and abruptly.
As a rule, such a protection system means that the aircraft is equipped with a fly-by-wire control system. Conversely, fly-by-wire control does not mean that an on-board system monitors the flight area.
The advantages of “Flight Envelope Protection” are that the crews can react violently in an emergency without their control commands endangering the aircraft. In this way, pilots can immediately initiate an evasive maneuver or a descent without first having to assess the risks of such a maneuver.
Use in commercial aircraft
The first airliner in which "Flight Envelope Protection" has been implemented to a significant extent is the Airbus 320 . It protects the aircraft from too high pitch, too high speed, too high g-force , too high angle of attack and too high bank angle .
Boeing and Airbus have taken different approaches to achieve the same goal. While the protection systems of modern Airbus aircraft (since the Airbus 320) set the pilots unable to exceed limits (unless they switch off the flight control computer responsible for this), in Boeing aircraft it is always the case with "Flight Envelope Protection" possible to exceed these limits. The only protection is that a much greater force is required to operate the control horn outside of the safe flight area.