Aero Flight 311

Aero Flight 311
Accident summary

Date	January 3, 1961
Summary	Pilot error, stall
Site	Kvevlax, Finland
Passengers	22
Crew	3
Fatalities	25 (all)
Survivors	0
Aircraft type	Douglas DC-3C
Operator	Aero O/Y
Registration	OH-LCC
Flight origin	Kronoby Airport
Destination	Vaasa Airport

Aero Flight 311 (AY311), often referred to as the Koivulahti air disaster, was a scheduled domestic passenger flight operated by Aero O/Y (now Finnair) between Kronoby, Finland and Vaasa. The aircraft, a Douglas DC-3C, crashed near Kvevlax (Finnish: Koivulahti) on January 3, 1961, killing all twenty-five people on board. The disaster remains the deadliest civilian aviation accident in the history of Finland.

The captain of the flight, a World War II fighter ace, was initially the target of the press after the accident, which was to change into blaming him after the police revealed both pilots were intoxicated when flying.^[1]

Flight chronology

The Douglas DC-3, registered OH-LCC, was scheduled to take-off at 7:00, but take-off preparations were late and the plane departed at 7:16. The co-pilot requested free flying altitude from the air traffic control, which was permitted. This allowed Flight 311 to fly at any altitude above the minimum flight altitude for the Kruununkylä-Vaasa route which was 1,500 feet (460 m). The pilots did not follow these regulations for the last 40 kilometres (25 mi), during which they flew below 100 metres (330 ft).^[2]

Memorial (in Swedish) to the dead in Kvevlax with the names of the victims

Shortly after the flight's last radio contact with the air traffic control, in which the pilots confirmed the weather report and said that they would be at the Seppä NDB radio beacon in a few minutes, the flight was starting to prepare for landing by descending below 50 meters. Next, the plane turned abruptly to the left. This slowed the plane and disrupted air flow significantly. The pilots tried to correct the situation by applying full throttle. This did not help and the plane went into a spin. The last thing seen by eyewitnesses on ground was that the pilots had turned the landing lights on before the plane crashed into the woods at 07:40:30 in a steep 70 degrees turn.^[3]

The first people to arrive at the scene after 10 minutes were unable to rescue anyone from the wreck burning in flames over 15 meters in height. The aircraft was extensively destroyed by impact forces and the fire.^[4]

Investigation

Tail of OH-LCC at the crash site.

The officials concluded that the plane had been completely airworthy, and that the probable cause of the accident was a pilot error when making a left turn. The possibility was noted that one passenger might have been present in the cockpit, based on his body location.^[5]

No evidence was found of any technical malfunction, of the plane hitting trees, nor of an explosion. It was possible that the plane controls had been frozen, as it was a cold winter day. The investigation report concluded that this was unlikely in the flying conditions, and an intact wing that had separated from the main wreckage did not have any ice on it. The pilots had not reported any icing on the plane via radio either.^[4]

According to the report by the Accident Investigation Board, the pilots, Captain Lars Hattinen, a World War II fighter ace of 6 victories, and co-pilot Paavo Halme, had not been in a fit state to fly. They had not slept well in the previous night, and they had been drinking heavily: in his autopsy, pilot Hattinen had a blood alcohol content of 0.20 (2 ‰), whilst co-pilot Halme had a BAC of 0.156 (1.56 ‰).^[6] All in all, the group that included one person more besides Hattinen and Halme, had drunk 16 bottles of beer, 7 gin grogs and 900 grams of cognac from 21:50 to 02:00.^[6] Hattinen had thus neglected his responsibility for the plane's and passengers' safety, and while co-pilot Halme had been in Hattinen's command, with no official responsibility to prevent him from flying, he too should not have been flying that day.^[7] It is against the International Civil Aviation Organization's treaty as well as the pilots' personal job contracts to be intoxicated in the plane, which the pilots had ignored.^[6] In the police interrogation, no one working at the airport said they had noticed that the pilots would be under the influence. Only a construction worker, whose brother was one of the victims, said he had noted the possibility based on their behavior but could not have been certain.^[6]

Flight number

Although airlines often retire the flight numbers of flights involved in fatal accidents, the successor of Aero O/Y, Finnair, continues to use flight number AY311 on its Helsinki–Vaasa route as of March 2009. The flights are operated with Embraer 170 aircraft.^[8]