What aircraft was involved and where did it happen?

The accident on 2005-04-18 involved a Bombardier DHC-8-314, at Hof-Plauen, DE.

What was the probable cause of the accident?

The incident was caused by a sudden loss of visibility due to heavy rain and water spray generated by the use of reverse thrust, leading to a loss of runway centerline orientation.

Loss of Directional Control During Landing at Hof-Plauen

A Bombardier DHC-8-314 veered off the runway at Hof-Plauen due to sudden visibility loss caused by water spray during reverse thrust application.

What happened

On April 18, 2005, at 21:34 local time, a Bombardier DHC-8-314 arrived at Hof-Plauen airport from Frankfurt, carrying 14 passengers and three crew members. The flight was conducted under instrument approach conditions via radar guidance. During the approach, heavy rain intensified, and visibility conditions deteriorated.

Upon touchdown on runway 27 at approximately 100 knots, the crew immediately applied reverse thrust on both engines to decelerate. The use of reverse thrust on the wet runway surface caused significant water spray to be kicked up, which rapidly obscured the crew's vision from the cockpit. Due to the lack of centerline lighting, the crew lost their orientation relative to the runway centerline. The aircraft drifted to the left, and the left main landing gear exited the paved surface, traveling approximately 150 meters onto unpaved terrain. During this excursion, the aircraft struck and destroyed a runway edge light and a taxiway boundary light, and sustained damage to two tires on the left main gear. The aircraft eventually returned to the runway and taxied to the parking stand under its own power. There were no injuries to the passengers or crew.

The investigation

The BFU examined the flight data recorder (FDR) and cockpit voice recorder (CVR), which confirmed the crew's accounts of the heavy rain and the impact of the water spray. The investigation reviewed the aircraft's maintenance records, finding no technical defects, and verified that the landing weight and center of gravity were within permissible limits.

The investigation also scrutinized the airport's meteorological reporting and the manufacturer's documentation. It was noted that while the tower reported a visibility of 3,000 meters, an electronic visibility meter near the tower recorded only 800 meters. Furthermore, the investigation looked into the operator's procedures regarding the use of reverse thrust on contaminated runways and the adequacy of the information provided by the airport regarding runway conditions.

Findings

The primary cause of the excursion was a rapid reduction in visibility caused by heavy rain and the spray of water kicked up by the application of reverse thrust immediately after landing.
The crew lost directional orientation because the runway centerline lights were not visible through the spray.
The aircraft manufacturer's Aircraft Flight Manual (AFM) did not provide sufficient guidance or specific procedures for using reverse thrust on wet runways, particularly regarding the risk of visibility impairment.
The crew was not adequately informed of the specific condition of the runway surface (water depth or contamination level) by the airport authorities.
The electronic visibility measurement system at the airport did not accurately reflect the actual visibility conditions experienced on the runway surface.

Safety action

Recommendation 12/2006: The aircraft manufacturer should incorporate specific instructions or procedures into the AFM regarding the use of reverse thrust when there is a risk of visibility degradation on contaminated runways.