Two days after the deadliest commercial plane crash in China in nearly six years killed 42 people in a remote northeastern city, doubts and speculations continue to swirl and no progress has been reported in the government investigation.

A brief press conference was held Thursday afternoon -- the first in more than 40 hours after a Brazil-made ERJ-190 turbine jet run by Henan Airlines crashed at Lindu Airport of Yichun, Heilongjiang Province.

But officials and an airline executive who addressed the conference did not say what caused the accident or whether their data analysis of the two black boxes found on Wednesday had achieved any results.

"The black boxes have been sent to Beijing and our specialists are still working on the data," said Lu Xue'er, an official in charge of aviation safety at the General Administration of Civil Aviation (CAAC).

A representative from Henan Airlines offered an apology and condolences to the victims and their families.

"We're grieved over the tragedy," said Liu Hang, Chairman of the Supervisory Board the airline. "Our condolences for the dead and apologies to all the victims, their families and the whole society."

He said his company had opened 24-hour hotlines at its headquarters in Zhengzhou, central Henan Province, Harbin and Yichun to help victims' family members arrange their trips.

Two local government officials also attended the press conference, which lasted for about 10 minutes and left no time for questions.

Before the press conference, everyone stood in silence tribute to mourn the dead.

Tuesday night's disaster ended CAAC's record 2,102 days of safe air travel in China -- 69 months without an accident.

Of all the 96 people on board, 54 survived with injures. Most of them were hospitalized in Yichun and 15 serious cases were airlifted to Harbin Wednesday night.

Among the serious cases were five children, aged from 6 to 10. Four of them suffered burns and two were still in critical condition, said doctors in Harbin.

Yichun Airport reopened Thursday with the landing of an Airbus 320 run by China Southern Airlines early in the afternoon, carrying some family members of the victims. It flew back to Harbin shortly afterwards, carrying passengers who had been laid over Tuesday night.

DOUBT, SPECULATION ABOUND

Initial probes and survivors' accounts indicated the plane missed the runway and crashed on the ground, breaking the cabin into two pieces and triggering a mild explosion.

No signs of sabotage have been found so far, investigators said

While several ground service staff at Lindu Airport said, on condition of anonymity, that it was foggy with low visibility when the plane crashed Tuesday night, the local weather bureau suggested otherwise.

The meteorological bureau of Yichun City, which regularly forecasts fog and other extreme weather conditions, found no signs of heavy fog that day.

"The city proper was not foggy at all between 9 p.m. and 10 p.m.," said Han Guangtian, the bureau chief. "Fog was possible at the airport, though, because it is located in a mountain valley surrounded by lush forests."

The forest area, he said, tends to be colder and more humid than the downtown areas, but still, "heavy fog was unlikely."

The industry watchdog, General Administration of Civil Aviation (CAAC), has not published any details of the accident, but citizens and several industry insiders said it was indeed foggy upon landing, the pilot should have landed at an adjacent airport in Jiamusi City.

The plane crashed at around 9:36 p.m. shortly after its captain told ground controller he was "ready for normal landing", a top official in Yichun said Wednesday quoting airport authorities.

Survivor Xue Xilai remembered the accident happened shortly after the crew announced they were about to land. "They didn't say it was foggy on the ground. Nor did the crew say there was any danger."

The airport was shrouded in thick fog throughout the rescue operation Tuesday night. Until 5 a.m. Wednesday, visibility was no more than 300 meters.

The captain, 40-year-old Qi Quanjun, did not say anything about the accident except that he "couldn't remember anything", when interviewed by Xinhua at Yichun's No. 1 Hospital Wednesday morning.

Hospital president Qi Xingzhong said he suffered facial injuries that could not have affected his memory or speech.

A source close to the pilot said he used to work for Shenzhen Airlines, the parent company of Henan Airlines, and resigned after he was demoted from captain to copilot. The man declined to be named.

"Frankly speaking, Qi's landing skills were so-so," said the source, who works at Mohe, another regional airport on China's northern border. "He became captain again at Henan Airlines."

Henan Airlines was previously known as Kunpeng Airlines. It flies smaller regional jets, mainly on routes in north and northeast China.

Li Jian, vice director of CAAC, defended Lindu Airport's safety standards late Wednesday, in response to speculations that inadequate facilities for night flights could have led to the disaster.

"It is no comparison to big airports but the safety standards are guaranteed," said Li.

He said the airport is built with the capacity to accommodate flights during the night.

But the airport has no fuel supplies and industry insiders say the plane has to be filled with enough fuel to cover the return trip, a possible reason for flames to spread fast.

Henan Airlines, for example, has only five jets, all ERJ-190.

"Because of their small fleet, smaller airlines companies tend to draw passengers with lower ticket prices. To meet their ends' meet, many buy regional planes -- which are often more risky and not as comfortable as jumbo jets -- and fly frequently at night," a source from civil aviation industry in Harbin told Xinhua.

The crashed jet might have flown some 6,000 km in 11 hours, taking off from Harbin at 8 a.m. and commuting to five regional airports in Mohe, Jiamusi, Jixi, Mudanjiang and Yichun, according to its schedule.

Had it landed safely in Yichun Tuesday night, it should have flown back to Harbin by 11 p.m.

It was the only jet to fly the routes every Tuesday, Thursday and Saturday.

Of Henan Airlines' remaining four ERJ-190 jets, three were in Zhengzhou and one was in Nanning, said Wu Zhenkun, a civil aviation spokesman in Henan Province. "The crashed jet is contracted on long term basis to Heilongjiang."

TOURISM BOOM

There was debate over the necessity for an airport in Yichun before construction began in 2008 -- the city was a five-hour bus ride from Harbin and two and a half hours from Jiamusi and both cities had airports already.

But last year's opening of Lindu airport has undoubtedly helped boosted tourism. And Friday will mark the first anniversary of its inauguration.

Yichun, known as China's "capital of woods" with over 80 percent of forest coverage, is an ideal summer resort for the Chinese from June to September.

Local residents said air tickets to Yichun are hard-won in summer and passengers needed to make reservation at least two days in advance to secure an economy class seat.

A night at a three-star hotel on the northern hills of the city, surrounded by virgin forests, costs nearly 1,000 yuan, five times its average price in winter, when the temperature falls below minus 20 degrees Celsius.