Incident Overview
On December 29, 2017, about 1840 Pacific Standard Time, Horizon Air flight 2184, a Bombardier DHC-8-402 (registration N412QX), landed on a taxiway parallel to runway 6 at Pullman/Moscow Regional Airport (KPUW), Pullman, Washington. The aircraft was operating under 14 CFR Part 121 on an instrument flight rules flight plan from Seattle/Tacoma International Airport (KSEA) to KPUW. Weather conditions at the time included wind from the southeast, light rain, an overcast ceiling, and 5 miles visibility. Night instrument meteorological conditions prevailed. The aircraft carried 42 passengers and crew; there were no injuries and the aircraft was undamaged. After landing, the flight crew observed that the runway lights were inoperative.
Flight Crew Information
The captain, aged 49, had accumulated 13,528 total flight hours, including about 5,997 hours in the Q-400. He was based in Medford, Oregon. The first officer, aged 38, had 1,582 total flight hours, including 95.5 hours in the Q-400. He was also based in Medford and had been hired by Horizon Air on July 10, 2017. Both pilots had no previous aviation incidents or accidents on record. Drug tests conducted the day after the incident were negative; alcohol testing was not performed. The captain and first officer had flown together on two preceding flight legs.
Aircraft Information
The incident aircraft was a Bombardier DHC-8-402, serial number 4059, manufactured in 2002. It was equipped with two Pratt and Whitney PW150A turbo-prop engines and registered to BCC Equipment Leasing Corporation in Seattle, Washington. The aircraft had no deferred maintenance items related to avionics, navigation, or the head-up display.
Weather and Airport Information
Meteorological reports valid at the time of the incident indicated rain, mist, and low ceilings. The terminal aerodrome forecast had predicted IFR conditions at the landing time. KPUW is an uncontrolled airport with two runways (06/24). Runway 06 is 6,730 feet long and 100 feet wide. The taxiway is approximately 57 feet wide. The distance between runway and taxiway centerlines is 200 feet. The airport was equipped with pilot-controlled lighting, including runway edge lights (HIRL), REIL, and PAPI. The runway lights were tested and found operational at about 1600 local time on the day of the incident. After the incident, airport personnel discovered flooded electrical wiring vaults from heavy rains, and NOTAMs were issued 43 minutes after the incident reporting the lighting out of service.
Approach and Landing
The flight crew was cleared for the RNAV (RNP) M instrument approach to runway 06. The captain, who was the pilot flying, used the head-up guidance system during the approach. He attempted to illuminate the airport lighting via the common traffic advisory frequency prior to the initial approach fix and again after exiting the clouds. The captain reported that he observed what he believed to be runway 06 and runway lights, though he questioned whether the lights were on bright or dim. He stated that he aligned the aircraft with illuminated pavement, which he believed was the runway, and did not notice taxiway lights. The first officer, during the flare, observed blue taxi lights and realized they were aligned with the taxiway. The aircraft landed uneventfully on the taxiway to the left of runway 06. After landing, the crew taxied the full length of the taxiway, then back-taxied on the runway to the gate. During the taxi, they attempted to change the lighting intensity via CTAF, noting that the blue taxiway lights changed but the runway lights did not illuminate.
Lighting System
Runway 06 at KPUW was equipped with high-intensity runway lights (HIRL) that emitted white edge lights and red/green end lights. Taxiway edge lights emitted blue light. The system was pilot-controlled via radio. According to the captain, he keyed the microphone multiple times in an attempt to adjust the lighting. The first officer reported that after landing, keying the microphone increased the intensity of the taxiway lights but not the runway lights. No NOTAM indicating inoperative runway lights existed before the incident. The NOTAMs published after the incident stated that the runway edge lights and runway end identifier lights were out of service.
Aftermath
The incident was reported to the National Transportation Safety Board. The aircraft was not damaged, and no injuries occurred. The flight continued to the gate without further incident.