Unalaska Saab 2000 Fatal Runway Excursion: PenAir N686PA 17 Oct 2019

Unalaska Saab 2000 Fatal Runway Excursion: PenAir N686PA 17 Oct 2019

The US National Transportation Safety Board (NTSB) has issued an investigative update for the 17 October 2019 runway overrun of PenAir Saab 2000 N686PA (Flight 3296) while landing at Tom Madsen Airport (PADU/DUT), Unalaska, Alaska (Port of Dutch Harbor).  This was only the second fatal accident involving a US Part 121 passenger airline since 2009.

PenAir Saab 2000 N686PA Unalaska, AK Runway Excursion (Credit: NTSB)

PenAir Saab 2000 N686PA Unalaska, AK Runway Excursion (Credit: NTSB)

The flight was cleared for the RNAV runway 13 approach into PADU.

Thomas Madsen Airport (PADU), Unalaska, Alaska in 1996 (Credit: via Wikipedia)

Thomas Madsen Airport (PADU), Unalaska, Alaska in 1996 (Credit: via Wikipedia)

The aircraft passed through the airport perimeter fence, crossed a road, struck a sign and came to rest on shoreline rocks. Two propeller blades entered the fuselage.

PenAir Saab 2000 N686PA Fuselage Damage (Credit: NTSB)

PenAir Saab 2000 N686PA Fuselage Damage (Credit: NTSB)

Of the 42 persons on board, one passenger was fatally injured and several others sustained injuries.

NTSB Safety Investigation

The NTSB say that:

According to the flight crew, the captain was the flying pilot and the first officer was the pilot monitoring. The first officer stated that he completed the performance calculations during cruise, before beginning descent, and prior to obtaining the weather at DUT. The flight crew indicated that they conducted a go-around during the first approach to runway 13 because they were not stabilized. On the second approach, the flight crew indicated they touched down about 1,000 feet down the runway and the captain initiated reverse thrust and normal wheel-braking. The captain stated that he went to maximum braking around the “80 knot call.” The flight crew reported that they attempted to steer the airplane to the right at the end of the runway to avoid going into the water.

The NTSB’s initial feedback from study of the Cockpit Voice Recorder (CVR) was that:

Weather was initially reported (by the local weather observer) as winds 210 degrees at 8 knots, gusting to 14 knots, visibility 7 to 10 miles, a ceiling at 4,300ft that was broken, a temperature of 8 degrees Celsius, a dew point of 1 degree Celsius, and an altimeter setting of 29.50 inches Hg. A later transmission from the local weather observer to another aircraft reported the winds were 180 degrees at 7 knots, visibility 8 to 10 miles with showers in the vicinity, and a broken ceiling at 3,900 feet.

The aircraft was configured for the approach: flaps 20, gear down.  During the approach, the winds were reported as 270 deg at 10 knots.  A go-around was executed, and the flight returned for a visual approach to runway 13. During the go-around, the winds were reported as 300 degrees at 8 knots.  After the go-around, the winds were reported to be 290 at 16 gust 30 (multiple overlapping radio transmissions occurred at this time).  Transmissions between the weather observer and another airplane indicated that winds favored runway 31 but could shift back to runway 13.

The aircraft was configured again for the approach: flaps 20, gear down. During the second approach, winds were reported as 300 degrees at 24 knots. The aircraft touched down and the roll out lasted approximately 26 seconds until the aircraft departed the runway.

The crew announced, over the PA, an evacuation out the right side of the aircraft and made a radio call for assistance.

Press reports indicate that only one emergency exit was opened.

The Flight Data Recorder (FDR) was examined:

Touchdown occurred with the aircraft travelling at about 129 knots indicated airspeed and 142 knots ground speed. Following touchdown, the aircraft decelerated reaching a peak deceleration of -0.48 g., with the engines operating in reverse mode. About 25 seconds after main gear touchdown, a change in aircraft pitch and roll, and an increase in the magnitude of triaxial acceleration forces was recorded, consistent with the aircraft departing the runway surface. The engines were taken out of reverse mode and ground speed at that time was about 23 knots.

NTSB note that:

Runway 13/31 at PADU is 4,500 feet long and 100 feet wide with a grooved asphalt surface.

There was a 5-inch-wide dark rubber witness mark on the runway, about 15 feet left of the runway centerline, starting about 1,840 feet from runway 13’s displaced threshold, and extending about 200 feet.  The left main landing gear outboard tire was found deflated with an area that had worn entirely through the tire.

PenAir Saab 2000 N686PA LH Outboard Tyre (Credit: NTSB)

PenAir Saab 2000 N686PA LH Outboard Tyre (Credit: NTSB)

Witness marks indicated that the airplane departed the runway and overrun area, traversed a section of grass, impacted a 3- to 4-ft high chain-linked perimeter fence with evidence of left engine propeller contact, crossed a ditch, impacted a large rock, and crossed a public roadway. The left wing or left engine propeller struck a 4 to 5 ft vertical signal post on the opposite shoulder of the road and the left propeller struck a 6 to 8-ft high yellow diamond shaped road sign. There were strike marks consistent with the right engine’s propeller tips contacting the ground near where the airplane came to rest.

Examination revealed a hole and significant impact damage to the left forward fuselage around the 5th window.

A propeller blade was loosely stuck in the surrounding structure external to the fuselage and another propeller blade was found inside the fuselage All cabin seats (15 rows) were intact and secure to the floor except for seat 4A, which was displaced and damaged. The damaged area of the cabin was contained within the area on the left side between fuselage station (FS) 399 (seat 3A) and FS 488 (seat 6A), with extensive damage evident at FS 435.

Part of the overhead compartment was hanging down or separated and the seat 4A window fuselage frame was found on the cabin floor.

Dowty R381 (Crtedit: Dowty Propellers)

The Saab 2000 is powered by two Rolls-Royce AE2001A turboprops fitted with Dowty R381/6-123-F/5 propellers (each with 6 composite blades).

The left engine remained attached to the engine mounts although the right rear engine mount was bent and buckled. The left engine’s propeller assembly was sagging in relation to the engine’s nacelle with the propeller shaft support resting on the forward part of the nacelle. The propeller reduction gear box front housing was fractured 360° around forward of the diaphragm and in the area of the ring gear. There were broken pieces of gear box housing laying on the engine deck. The propeller shaft aft bearing was missing 3 adjacent rollers from the bearing cage. The engine was complete and did not have any indications of an uncontainment or case rupture.

PenAir Saab 2000 N686PA LH Prop / Engine (Credit: NTSB)

PenAir Saab 2000 N686PA LH Prop / Engine (Credit: NTSB)

The left propeller hub was intact. Pieces of the blade, either part of the airfoil or just the blade butt, remained in all six blade locations on the hub. All of the propeller blades that still had parts of an airfoil remaining were in the feathered position. At those locations were the airfoil was missing, the blade retaining clamps were in place with the retaining bolts in place and safety wired. Blades Nos. 1, 3 and 4 were missing, although the base of each blade remained in the hub.  Blade No. 2 was in place in the hub and the blade was fractured transversely across the airfoil about 28.5-inches from the disk to the fractured end. Blade No. 5 was broken about 48-inches from the disk to the fractured end. Blade No. 6 was broken about 48-inches from the disk to the fractured end.

The three missing blades were all recovered.

There was a propeller blade that was recovered from the water that was about 48-inches long. There was a propeller blade that was found hanging on the left side of the airplane from some cabin insulation that had wrapped around the butt of the blade that was about 58.5-inches long. There was a blade that was found in the cabin that was about 57-inches long.

PenAir Saab 2000 N686PA LH Side (Credit: NTSB)

PenAir Saab 2000 N686PA LH Side (Credit: NTSB)

The wreckage was lifted by crane barge on 19 October 2019.

Both crew held ATPLs but were low time on type.

 The captain…had accumulated about 20,000 total flight hours of which about 14,000 hours were in the DH-8 and 101 hours were in the Saab 2000. The first officer…had accumulated 1,446 total flight hours of which 147 were in the Saab 2000.

Press reports claim:

PenAir…had a “captains only” rule for takeoffs and landings and a 300-hour minimum in-aircraft as PIC requirement. According to former and current PenAir pilots, this has changed under the new ownership. A page dated April 25, 2019, from the PenAir Operations Manual, states that the 300-hour PIC minimum may be waived if a company check airman who has flown with the pilot provides a letter of recommendation and the Chief Pilot approves the exception.

PenAir had previously gone through bankruptcy and was sold in October 2018. It is now majority-owned by the same Manhattan-based private equity firm, JF Leman, that owns Ravn Air Group, an operator which has come under scrutiny for safety issues previously.  PenAir has stop operating the S2000 to Unalaska and Ravn has instead resumed flights with a Dash 8.  Codeshare partner Alaska Airlines has cancelled all reservations to and from Unalaska through to 31 May 2020. 

We will update this article as further information is released by NTSB.

Video of a SF340 landing:

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