R ESULTS of the preliminary investigation into the country's worst commercial airline
disaster began to surface this week, as Vietnam Airlines and Cambodian aviation officials
squared off over who was at fault.
Cambodian investigators suggested pilot error while Vietnam Airlines suggested
that weather information given before take-off was inaccurate. All but two of the
66 passengers and crew of flight VN815 from Ho Chi Minh City perished on Sept 3.
The crash occurred at about 1:40 pm in cloudy weather.
Final conclusions will not be possible until "black box" flight-recorders
from the ill-fated Tupolev134B aircraft are analyzed.
"We cannot make any decision about the cause of the crash yet. We have to base
that on the black boxes," said acting airport director and investigating committee
chief Sok Sambour. "There are three black boxes on the plane: one for the audio,
one for flight data and one stand-by."
Authorities have recovered all three recorders. Sambour acknowledged that officials
"bought" at least one of them back from villagers who had salvaged it from
Without the equipment to extract voice and flight data from the boxes in Cambodia,
investigators were still debating at Post press time where to send them for analysis.
"We plan to send the black boxes to Russia, but we are afraid that the Russian
government will not agree to that. If they do not agree, maybe we will ask the representative
of the manufacturer to come to examine it," he said. "If not, maybe it
will be made in Vietnam. We need a third country to be a neutral referee."
The director of Vietnam Airlines, Le Duc Tu, was quoted in the Vietnamese press as
saying that the pilot was given inaccurate weather information by air-traffic controllers
at Pochentong before take-off.
Cambodian aviation officials declined to respond to the charge, but did raise
the issue of pilot error.
Sambour stated that the pilot had not followed air-traffic control instructions,
and that the pilot appeared to have consistently breached Cambodian aviation rules
during the failed approach and landing by coming in too low.
According to Sambour, the plane was supposed to be at 14,000 feet when it began its
approach, but was at 10,000 when it reached the range of Pochentong's Non-Directional
Beacon (NDB) - a device which indicates the distance between it and a plane. "We
think that this pilot did not respect our order.
"Then he asked permission to land at 5,000 feet and the tower agreed about the
altitude, but said that the pilot would have to remind the tower often," he
said. "But when this plane approached the airport it was at 3,000 feet and asked
for permission to land."
He said the pilot radioed that he still could not find the runway and was given permission
to drop to 2,000 feet and told to keep in contact.
"A moment later, we asked them if they found the runway and they responded:
'We cannot see the runway'. We then told them that the wind direction was changing,
so we asked the plane to approach from the west," he said. "The plane could
not land from the east because the plane would be landing downwind. They told us
that they had received the order and would follow it."
He added, however, that the pilot had the discretion to use his own judgement when
landing. "Even if the tower orders the pilot to change direction, it is up to
the commander of the flight, because he is the person really in charge," he
said. "He can land it if he thinks that he can do that in his capacity."
That was the last radio signal from VN815, according to Sambour. Two minutes later,
tower operators saw the plane approach from the east - flying fast and low - missing
the runway to the south. "We saw the plane emerge in the east and hit the top
of the tree," he said.
The disaster begs the question of airline safety at Pochentong. Aviation officials
insist that airport is safe, but privately admit that sophisticated navigation equipment
was looted after the fighting in Phnom Penh in early July.
"We had equipment donated by UNTAC that was particularly useful in heavy rain,"
said an official who declined to be identified. "It was called 'VOR/DME, or
Very-high frequency Omni-directional Distance Measurement Equipment, which could
alert a pilot when he was off course. It was worth more than $1.5 million."
He said that he did not know if the aging TU134B had the equipment on board to utilize
it, but stressed that the pilot was aware that Pochentong did not have one. "The
pilot needs to be more precise when landing. He needs visual contact."
Investigators are also questioning whether runway lights were on or water obscured
the runway because a pump was looted. "When the weather is bad or the sky is
a bit dark we put the lights on. I have no idea if on Wednesday afternoon they were
on," said a Cambodia Airport Management Services official.
One pilot familiar with Pochentong shifted the onus of blame from the airport. "When
it comes to air safety, it is up to the pilots. This kind of equipment goes out all
the time. The pilots have to make the choice whether to land. It's not the airport's
He said that accidents in tropical storms follow a general pattern. "You get
what you call 'micro-bursts' where one minute you are flying into the wind and a
couple of kilometers later you are in a tailwind. In the middle of the storm, the
wind moves downwards and that is a problem. Forty to sixty tonnes takes a while to
come up to speed."
He discounted the importance of accurate weather information before take-off during
this time of the year. "It is almost impossible to predict even 30 minutes in
advance what the weather will be like when you land at Pochentong," he said.