State’s worst plane crash is also its most mysterious

By Finn J.D. John
December 17, 2017

WHEN A COMMERCIAL airliner crashes, it’s very rare to have absolutely no idea what happened. Even if the cockpit voice recorder is destroyed, usually there are enough clues left at the scene to piece together a picture of how the disaster came about.

But every now and then, a crash happens that offers a complete mystery — the aviation equivalent of one of those derelict barnacle-crusted sailing-ship hulls that used to drift ashore, empty and lifeless, on the Oregon Coast, the story of its crew’s demise forever unknown.

Such is the case with the worst airplane crash in Oregon state history, as measured in lives lost: The Oct. 1, 1966 crash of West Coast Airlines Flight 956, a brand-new Douglas DC-9 that apparently drove, on autopilot, straight into the side of a ridge near Mount Hood with 18 people aboard.

There are a few theories that have been put forward about what happened that night, and we’ll look at them. But none of them can claim much more than a 50-50 chance. In the end, the story of Flight 956 remains a mystery.

WEST COAST AIRLINES was a small regional airline, best known for making short hops around small airports like Bend and Eugene and Klamath Falls using Fairchild F-27 turboprop planes. But Flight 956 wasn’t one of those; it was a genuine jet airliner, a Douglas DC-9, one of the flagships of the West Coast fleet; and it was brand-new. The airline quite literally bought it on Monday and crashed it on Saturday. It had less than 170 hours on it.

As was fitting for one of the airline’s flagships, Flight 956 was making one of West Coast’s most prestigious runs: from San Francisco to Seattle, with stops at Eugene and Portland. It had left San Francisco at 6:44 p.m.; touched down at Eugene at 7:34; and was scheduled to land at PDX less than an hour later.

At 7:52, pilot Donald Alldredge took off from the Eugene airport and flew the jet up to 14,000 feet for the short flight to the outskirts of Portland. Then, having been cleared to come to 9,000 feet, he started a descent.

It’s at that point that the mysterious part happens. Because rather than leveling off at 9,000 feet as instructed, the jet continued its descent — down to 4,000 feet, and below. But no one seems to have noticed. The airplane continued following directions from the tower, making turns and getting ready for the approach as if it were cruising along at 9,000. According to the flight data recorder, nothing changes until two seconds before impact, when suddenly the plane starts a sharp climb — either the pilot grabbed the yoke and pulled back, or the autopilot (which was found to be still engaged at impact) was reacting to something.

Five minutes later, having fruitlessly tried to get the pilot on the radio several times, the tower initiated accident notification procedures.

“I had him on my radar about 30 miles southeast of Portland, and he was on an 080 course (flying almost due east),” said air traffic controller W.R. Gibson, according to the Oregonian’s front-page story on the crash. “I estimated his speed at between 300 and 350 knots. I looked away from the screen a minute while expanding my range to 50 miles, and I never saw him again.”

The jet lanced into the side of a ridge about four miles south of Welches at full cruising speed — close to 400 miles an hour — shearing off the tops of trees before hitting the ground and disappearing into a giant fireball. The wreckage was 3,830 feet up a 4,090-foot ridge, and the plane had probably been flying as low as 3,500 feet.

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SO: WHAT HAPPENED? Your guess is as good as the National Transportation Safety Board’s.

“A correlation of communications with the flight and the flight recorder trace reveals that all clearances and instructions were received, understood, and complied with, except the altitude restriction of 9,000 feet,” the accident report notes, with almost palpable puzzlement.

The cockpit voice recorder was melted in the fire, so there can be no help from that quarter. The flight data recorder shows nothing but calm, unhurried preparations for a routine landing — every detail professionally and competently executed, but at an altitude 5,500 feet below the assigned one.

“The board concludes that the reason for the aircraft being permitted by the crew to descend below the assigned altitude is unknown,” the report concludes.

THERE ARE A few guesses at what might have happened; but none of them are more than speculation.

One theory is that the crew overheard an instruction to another flight coincidentally also numbered 956, coming into Seattle, to descend to 4,000 feet, and complied. But this theory can literally be dismissed out of hand. There is no record of the flight crew acknowledging an instruction to drop to 4,000, as there is of every other instruction given to them that night; and with three veteran jet pilots in the cockpit — all of whom were familiar with the terrain around PDX, which gets very steep very quickly on the eastern perimeter — there is just no way such a dangerous order would have been complied with without at least a request for clarification.

By the same token, we can safely assume that the pilot would not have flown into PDX at 4,000 feet on purpose. If we make that assumption — and if we set aside the “X Theories” such as a hijacking, a super-precise lightning strike, an alien abduction, etc. — there are really only two possibilities: Either a piece of equipment malfunctioned (such as the altimeter or the autopilot); or the crew was distracted from it by some unknown crisis in the cockpit and failed to pay attention to the altimeter.

But, of course, we’ll never really know.

THIS PLANE CRASH was the worst in Oregon history, with a total death toll of 18 souls — 13 passengers and five crew members. It could, of course, have been much, much worse; the basic DC-9 can hold up to 109 people, although more typically they seat 70 to 90 plus crew.

It was the first fatal plane crash in the 20-year history of West Coast Airlines — although, unfortunately, not the last. It was also the first DC-9 crash in all of aviation history; the first DC-9 had gone into service with Delta Airlines just 10 months before, in December 1965.

The crash site is remote and rugged, but can be reached on a day hike. The plane is broken into tiny fragments, some of it still melted and discolored by the heat.

(Sources: National Transportation Safety Board report AAR67-AF; wreckchasinginoregon. blogspot.com; Portland Morning Oregonian back issues, October 1966)

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