Visibility had worsened significantly when a passenger plane of South Korea's No. 2 flag carrier Asiana Airlines Inc. crash landed at an airport in Japan last month, a preliminary investigation showed Wednesday.

The results of the month-long investigation conducted by the Japan Transport Safety Board, however, did not pinpoint the exact cause of the accident that took place in mid-April. Nor did it mention any possible fault or mistake by the pilots that could have led to the accident.

The results were announced in Japan, then translated into Korean and made public by the transport ministry here.

On April 14, the Asiana Airlines plane, carrying about 80 passengers and crew members, came to a stop after veering off the runway as it landed at Hiroshima Airport. No passengers were seriously injured.

According to the investigation results, it was lightly raining and the wind was not strong, blowing at around 2-3 knots, when the plane came in to land. However, visibility worsened abruptly from over 1,800 meters to 400 meters just two minutes before the accident.

The airplane collided with a 4-meter guiding light pole and its engines and landing gears hit a localizer antenna before coming to a halt, they said.

When it came in to land, the plane flew at an almost constant speed of about 131 knots, but it seems the pilots tried to lift the aircraft just before hitting the light pole. The output of the plane engines showed no sudden spike at the time of the accident, they noted.

The transport ministry here said it will keep working together with Japanese authorities to figure out the exact cause of the accident. Experts expect that it will take about a year to determine.

An Asiana Airlines official declined to elaborate, saying it is not appropriate to comment on the ongoing probe, but he added that the company continues to cooperate with authorities in Korea and Japan.

Earlier, Asiana Airlines said it will compensate all the passengers on board by paying $5,000 to each. (Yonhap)