Improper maintenance, poor judgement by the flight crew and the FAA’s decision to approve the airline to operate out of the accident airport have been cited as causal factors in the deadly runway overrun by a Saab SA-2000 in Unalaska, Alaska in 2019.
On Tuesday, the NTSB held a meeting to determine the causal factors of the accident and made recommendations to improve safety.
What Happened
The accident happened on October 17, 2019, when the Saab SA-2000—operated by PenAir as flight 3296—was attempting to land. According to the accident abstract published by the NTSB, the flight crew’s first attempt to land on Runway 13 resulted in a go around. When the airplane entered the traffic pattern for a second landing attempt, the flight crew learned the wind was from 300 degrees at 24 knots. The captain chose to continue the approach to Runway 13, rather than maneuvering to land on Runway 31, although it meant landing with a tailwind of at least 15 knots.
The captain reported that the touchdown was normal, but when maximum braking was applied, there was “zero braking” action. The aircraft overran the runway and the adjacent 300-foot runway safety area off the end of the pavement. The turboprop crashed through a fence and came to rest on the rocky bank of Dutch Harbor. One person, 38-year-old David Oltman of Ellensburg, Washington, was killed when a piece of a propeller broke off during the crash and pierced the cabin. One person was seriously injured and eight more people suffered minor injuries during the evacuation from the aircraft.
Neither the flight crew nor the remaining 29 passengers were hurt.
The NTSB said the decision to land with such a tailwind was “intentional, inappropriate, and indicative of plan continuation bias.” The board went on to state: “The safety margin was further reduced because of PenAir’s failure to correctly apply its company-designated PIC airport qualification policy, which allowed the accident captain to operate at one of the most challenging airports in PenAir’s route system with limited experience at the airport and in the Saab 2000.”
The runway, measuring 4,500 feet by 100 feet, has a reputation for being a difficult operating environment. It’s located at the base of a mountain and flanked on both sides by water.
During the hearing, the NTSB received testimony indicating the lack of braking action was caused by “incorrect wiring caused the anti-skid system not to function as intended, resulting in the failure of the left outboard tire and a significant loss of the airplane’s braking ability, which led to the runway overrun.”
The NTSB stated the design of the braking system was partially to blame for the maintenance error, as it is complicated and confusing to maintain.
The NTSB also noted that when the FAA approved PenAir to fly in and out of the Unalaska airport with the Saab 2000, “they did not recognize that the safety area beyond the end of the runway did not conform to the recommended safety criteria for an airplane in that design category.”
A 2007 report published by the International Civil Aviation Organization noted that except under special conditions, the Runway Safety Area standard dimensions for runways used by aircraft with approach speeds of 121 knots or more are 500 feet wide and 1,000 feet long.
“Even though the airplane, the pilot, the weather and federal oversight all had a role in this tragedy, it was entirely preventable,” NTSB Chair Jennifer L. Homendy said. “The brake system should have been designed to protect against human error during maintenance, the pilot shouldn’t have landed on a runway with such a strong tailwind and federal regulators should have considered the runway safety area dimensions when authorizing the airline to fly the Saab 2000 into that airport.”
Recommendations
The meeting concluded with the NTSB issuing several recommendations to the FAA and the European Union Aviation Safety Agency and to Saab to prevent further accidents.
These include:
- A review of safety assessments for landing gear systems on currently certificated transport-category airplanes to determine if more needs to be done to prevent the cross-wiring of components
- Require transport-category airplane manufacturers without such assessments to implement the mitigations
- Require system safety assessments addressing the landing gear anti-skid system for the certification of future transport-category airplane designs
In addition, the NTSB recommends that Saab redesign the wheel-speed-transducer wire harnesses for the Saab 2000 to prevent the harnesses from being installed incorrectly during maintenance and overhaul, and that the FAA and the EASA require organizations that design, manufacture, and maintain aircraft to establish a safety management system.
The NTSB also noted that it’s possible that safety risks can result when certificate holders experience significant organizational change, such as bankruptcy, acquisition, and merger.
All three were experienced at PenAir more than two years before the accident. Citing this, the NTSB suggested that the FAA revise agency guidance to include a formalized procedure for these transitions to ensure that incoming personnel are fully aware of potential safety risks.
The NTSB also suggested that the FAA pay more attention to the runway design code for runways of intended use when authorizing a scheduled air carrier to operate its airplanes under specific airfields under Part 139 on airport operations.
