Northwest Orient Airlines Flight 324

Investigation

Since the accident occurred on Canadian soil, the Canadian government led the investigation and invited the Civil Aeronautics Board (predecessor of the National Transportation Safety Board)

to send an observer. The CAB conducted its own investigation alongside the Canadian government. One of the survivors was First Lieutenant Donald E. Baker, a United States Air Force navigator. Lt. Baker was present inside the cockpit until the start of the final approach into Sandspit.

Lt. Baker advised that near Sitka, the pilots noted a rapid loss of oil pressure in engine No. 1. The engine was shut down and clearance was given to proceed to Sandspit. At the time of the engine failure, Annette Island Airport was closer and equipped with better facilities, but was unavailable due to poor weather conditions.

After the No. 1 engine failed, some ice formed on the forward cockpit window. The pilots flew up to 9,000 ft from 8,000 ft to avoid further ice accretion. According to Lt. Baker, the plane performed well on three engines and there were no handling difficulties.

There was light turbulence during the descent, although to Lt. Baker the approach seemed normal. The final approach was a bit high and the touchdown had little flare-out. After power was applied for the go-around, Lt. Baker felt vibrations that he associated with an impending stall. The plane impacted the water twice. The deceleration was considered rapid but not violent.

Ditching had not been anticipated and passengers had not been instructed to prepare for an abnormal landing. All or nearly all passengers evacuated the aircraft through the left cabin emergency exit, the main cabin door, and the astrodome. None of the life rafts were successfully launched. All passengers had been given emergency pamphlets upon departure from Tokyo describing life raft operations.

On June 9, 1952, divers visited the wreckage during an unusually low tide. The plane was nearly disintegrated due to tide action and corrosion. The nose gear had washed up on the beach shortly after the accident. Normally, the nose gear retracts before the main landing gear on the DC-4, but in the event of a malfunction, it can retract only partially.

Northwest Airlines noted many instances when a DC-4's nose gear failed to fully retract. All the malfunctions occurred during cold weather and during crosswind takeoffs which require nose wheel steering (as do three-engine takeoffs, like the accident aircraft's).

Maintenance records revealed that certain component parts of the No. 1 engine had exceeded their 1,500 hours between overhauls. The engine in question had been in operation for an excess of 225 hours past its overhaul due date. This oversight was due to a clerical error at Northwest Airlines.

Findings

"On the basis of all available evidence, the Board finds that:

1. The company, the aircraft (with the exception of certain components of No. 1 engine), and the crew were properly certified.

2. The No. 1 engine suffered an oil loss, which necessitated shutting down the engine and feathering the propeller.

3. In accordance with company operating procedures, the captain elected to land at the first available airport, rather than continue to destination on three engines.

4. The landing at Sandspit was aborted and a go-around was started.

5. When last observed by a ground witness, the aircraft was in a shallow left bank at low altitude.

6. During the attempted climbout, the aircraft settled into the water, bounced, and came to rest 26 degrees to the left and approximately 4,500 feet from the end of the runway.

7. While all or nearly all of the passengers evacuated the aircraft with no known serious injuries, drownings and exposure accounted for 36 fatalities due to near freezing air and water temperature.

8. No steps were taken to prepare passengers for a crash landing or possible ditching.

9. Emergency lighting in the cabin was not utilized, nor were any effective measures taken to use life rafts stowed at the rear of the cabin."

Probable cause

The Civil Aeronautics Board determined that "the probable cause of this accident was a nose gear retraction difficulty in connection with an icing condition or a power loss, which made the aircraft incapable of maintaining flight."