JAKARTA (AFP) - Hundreds of Indonesians descended on the Juanda international airport on Sunday hoping for news of the missing Indonesia AirAsia flight QZ8501.
A 45-year-old woman told AFP that she had six family members on the plane.
"They were going to Singapore for a holiday," she said.
"They have always flown with AirAsia and there was no problem. I am shocked to hear the news, and I am very worried that the plane might have crashed."
Indonesia, a vast archipelago with poor land transport infrastructure, has seen an explosive growth of low-cost air travel over recent years.
But the air industry has been blighted by poor safety standards in an area that also experiences extreme weather.
Air traffic controllers lost contact with Flight QZ8501 around an hour after it left Juanda international airport in Surabaya, east Java, at 5:20am.
The Airbus A320-200 had been scheduled to arrive in Singapore at 8:30am.
The airline said of the 162 onboard, 156 were Indonesians, three were South Koreans and there were one person each from Singapore, Malaysia and France.
There were 138 adult passengers, 16 children and an infant, in addition to the two pilots and five cabin crew.
The Indonesian air force said two of its planes had been dispatched to scour an area of the Java Sea, southwest of Pangkalan Bun in Kalimantan province.
"The weather is cloudy and the area is surrounded by sea. We are still on our way so we won't make an assumption on what happened to the plane," said Indonesian air force spokesman Hadi Cahyanto.
The aircraft was operated by AirAsia Indonesia, a unit of Malaysian-based AirAsia which dominates Southeast Asia's booming low cost airline market.
With hard details few and far between, panicked relatives gathered at Singapore's Changi airport.
The company swiftly replaced its distinctive bright red logo to a grey background on its social media pages.
An official from Indonesia's transport ministry said the pilot asked to ascend 6,000 feet to 38,000 feet to avoid heavy clouds.
"The plane is in good condition but the weather is not so good," Djoko Murjatmodjo told a press conference at Jakarta's airport, addressing reports of severe storms in the area where the jet went missing.
Murjatmodjo said search efforts were being focused on an area between Belitung island and Kalimantan, on the western side of the island of Borneo, about halfway along the flight's expected route.
Singapore has offered help from its navy and air force in the hunt for the plane.
The White House said US President Barack Obama had been briefed on the disappearance and that it was monitoring the situation.
The plane's disappearance comes at the end of a disastrous year for Malaysian aviation.
Malaysia Airlines Flight MH370, carrying 239 people, vanished in March after inexplicably diverting from its Kuala Lumpur-Beijing course. No trace of the aircraft has been found.
Just months later another Malaysia Airlines plane went down in July in rebellion-torn eastern Ukraine - believed to have been hit by a surface-to-air missile - killing all 298 aboard.
AirAsia's flamboyant boss Tony Fernandes, a former record industry executive who acquired the then-failing airline in 2001, tweeted: "Thank you for all your thoughts and prayers. We must stay strong."
His airline, Asia's budget leader, has seen spectacular success and aggressive growth under his low-cost, low-overhead model.While its rival Malaysia Airlines faces potential collapse after two disasters this year, AirAsia confirmed this month its order of 55 A330-900neo passenger planes at a list price of US$15 billion.
AirAsia said the missing jet last underwent maintenance on Nov 16.