What happened
On May 31, 2013, a Boeing 737-800 was conducting an instrument approach to runway 21 at Eindhoven Airport under instrument meteorological conditions. Following instructions from air traffic control to fly a shorter route, the aircraft descended to a level that placed it above the standard 3-degree glide slope.
As the aircraft attempted to intercept the ILS glide slope from above, the nose pitched up abruptly by approximately 24.5 degrees within an eight-second period. This sudden maneuver triggered a stick shaker warning, indicating an imminent stall condition. The crew immediately responded by initiating a go-around using the TOGA (take-off/go-around) mode. During the subsequent recovery maneuver, the stick shaker activated a second time briefly. The crew successfully completed the go-around and landed the aircraft safely at Eindhoven Airport.
The investigation
The Dutch Safety Board (OVV) examined the flight data, cockpit voice recordings, and air traffic control transcripts. The investigation focused on the flight path management and the automation behavior of the aircraft's autopilot and autothrottle systems. Investigators analyzed the sequence of events leading to the glide slope interception and the impact of the modified arrival route on the aircraft's vertical profile.
Findings
- The aircraft was flying a non-standard approach path due to a shorter route assigned by air traffic control.
- The aircraft intercepted the ILS glide slope from an altitude significantly higher than the standard path.
- The abrupt pitch-up of the aircraft's nose was the primary cause of the aerodynamic instability.
- The activation of the stick shaker presented a high-risk situation that could have led to a loss of control or a crash if not managed correctly by the crew.