DHC-8-314 Off-Runway Excursion at Hof-Plauen

Event Overview and Aircraft Details On 18 April 2005, a Bombardier DHC-8-314, a twin-turboprop airliner built in 2000 and powered by Pratt & Whitney PW123B engines, landed at Hof-Plauen Airport (EDQM) from Frankfurt. The aircraft, serial number 544, carried 14 passengers and three crew members. It had 10,494 flight hours and 10,227 landings at the time of the incident. The landing mass was 15.4 t, within approved limits. ## Approach and Landing The aircraft conducted an instrument landing system (ILS) Category I approach to runway 27, guided by Nürnberg Radar. During the approach, rain intensified, reducing visibility. The aircraft touched down at approximately 100 kt. Immediately after touchdown, both propellers were placed in reverse thrust to decelerate. ## Off-Runway Excursion According to the crew, water spray from the wet runway severely reduced visibility. The absence of centerline lighting prevented the crew from maintaining the aircraft's position on the runway. The aircraft drifted left and, over a distance of about 150 m, the left main landing gear entered an unpaved area. The aircraft returned to the runway and taxied to its parking stand under its own power. ## Damage and Injuries The aircraft left the runway with the left main gear about 60 m before the half-runway marking, destroying a runway edge light. At the intersection with taxiway B, a taxiway boundary light was also destroyed. Two tires on the left main landing gear were damaged. No passengers or crew were injured. ## Investigation Findings The BFU investigation found that the approach and landing were conducted in accordance with applicable regulations and company procedures. The weather conditions were sufficient for a Category I ILS approach. However, the use of reverse thrust on the wet runway caused a spray bubble that rapidly degraded visibility, leading to a loss of directional control. The aircraft manufacturer's documentation did not adequately address the use of reverse thrust on wet runways. The operator's existing procedures only advised avoiding reverse thrust on icy or slippery runways and did not cover the specific visibility and directional control issues encountered. Following the incident, the operator updated its procedures to warn that reverse thrust can cause yaw instability and a spray bubble, particularly on wet runways, and to use it only in accordance with directional control and visibility. The BFU also noted that the visibility measurement device near the tower appeared to be poorly located, as its reading of 800 m differed significantly from the 3,000 m reported by the tower. The crew was not adequately informed of the runway condition, though they should have assumed a wet or contaminated runway given the weather.