A device that determines the critical angle of attack for a given aircraft, at which point the lift stops increasing and the aircraft will no longer sustain itself in steady-state condition (level flight or climb/descent). The indicator usually operates from vane sensors, airflow pressure sensors, tabs on the leading edge of the wings, and computing devices which include accelerometers, airspeed detectors, and vertical gyros. The indicator may be a pointer over a dial, lights, or an audible signal. In some cases, the computer may actuate a control-column shaker to alert the pilot.