Aero Flight 311

Flight route

The Douglas DC-3, registered OH-LCC, was scheduled for take-off at 7:00 a.m., 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]^:17

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 metres (160 ft). Suddenly, 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 the 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-degree turn.[2]^:18

The first people to arrive at the scene after 10 minutes were unable to rescue anyone due to the wreck burning in flames over 15 metres (49 ft) in height. The aircraft was extensively destroyed by impact forces and the fire.[2]^:19

The officials concluded that the plane had been airworthy, and the probable cause of the accident was pilot error when making a left turn. It is possible that one passenger might have been present in the cockpit, based on his body location.[2]^:20

No evidence was found of any technical malfunction, of the plane hitting trees, or 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.[2]^:19

According to the report by the Accident Investigation Board, neither the pilot Captain Lars Hattinen nor the co-pilot Veikko Halme were in a fit state to fly. They had not slept well the previous night, and they had been drinking heavily. Autopsies revealed that pilot Hattinen had a blood alcohol content of 0.20 (2 ‰), while co-pilot Halme had a BAC of 0.156 (1.56 ‰).[2]^:15 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.[2]^:15 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.[2]^:14[3] Both the International Civil Aviation Organization's treaty and the pilots' personal job contracts barred intoxication while in command of a plane—provisions that the pilots ignored.[2]^:15 In the police interrogation, no one working at the airport said they had noticed that the pilots were intoxicated. 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.[2]^:15 Both Captain Hattinen and co-pilot Halme were World War II veteran pilots with Hattinen being a former fighter ace having six aerial victories, and used to take grave risks on combat flights.

Although airlines often retire the flight numbers of flights involved in fatal accidents, the successor to Aero O/Y, Finnair, continued to use flight number AY311 on its Helsinki–Vaasa route for a long time. The flight number was eventually changed to AY313. The flights are operated mainly with Embraer 190 or ATR 72, but some busy Monday and Friday flights are operated by Airbus A320 family aircraft.[4]

• Aero Flight 217, Aero O/Y's other fatal DC-3 accident in 1963
• JAL Cargo Flight 8054, a fatal DC-8 accident in 1977 where the captain was intoxicated

Media related to Aero Flight 311 at Wikimedia Commons

• AirDisaster.com account of the crash (Archive)
• Accident description at the Aviation Safety Network
• Official report by the Accident Investigation Board Finland (in Finnish)