Indonesia: grief and disbelief among relatives of passengers on Sriwijaya Air flight

"Bye-bye, family. We're heading home for now," Ratih Windania posted on Instagram from Jakarta's airport, with pictures of two laughing children and two emojis blowing kisses.

The message was sent just before they boarded a plane from the Indonesian capital on Saturday that crashed into the sea minutes after take-off, carrying 62 passengers and crew.

"Pray for us," her brother Irfansyah Riyanto posted on Instagram with a picture of the family.

The Indonesian authorities said they had recovered pieces of wreckage and human remains on Sunday from the waters north of the capital where Sriwijaya Air Flight 182 disappeared in rainy weather.

Like dozens of other desperate relatives, Irfansyah rushed to Jakarta's Soekarno Hatta International Airport late on Saturday. On Sunday, he was still hoping for good news about his sister and four other family members on the flight, including his parents.

"We feel powerless. We can only wait and hope to have any information soon," he said.

Irfansyah said his relatives had originally been due to take an earlier flight operated by Sriwijaya's unit NAM Air and he was unclear why that was changed.

His sister and her two children had been at the end of a three-week holiday and were taking the 740-kilometre trip home to Pontianak in the province of West Kalimantan.

"I was the one who drove them to the airport, helped with the check-ins and the luggage ... I feel like I still can't believe this and it happened too fast," Irfansyah said.

The flight disappeared from radar screens minutes after the plane took off and reached an altitude of 3,300 metres.

The Indonesian authorities said they tracked signals believed to be from the plane's black boxes on Sunday. Police asked families to provide information, such as dental records and DNA samples, to help identify any bodies retrieved.

At hospital, the brother of co-pilot Diego Mamahit said he had been asked for a blood sample.

"I believe my younger brother survived; these are just for the police procedure," Chris Mamahit said. "Diego is a good man. We still believe Diego survived."

On his LinkedIn profile, Mamahit had written: "I really love to fly."

He and the pilot, Afwan, who goes by only one name, had nearly two decades of commercial flying experience between them. Afwan had previously been an air force pilot.

"We the family still hope for good news," a family member of Afwan, a devout Muslim, told Detik.com.

Indonesian President Joko Widodo offered his sympathies on Sunday.

"We are making our best efforts to find and rescue the victims and we all pray that they can be found," he said.

Panca Widiya Nursanti, a middle-school teacher in Pontianak, had been returning after a holiday in her home town of Tegal in Central Java. In Pontianak, her husband Rafiq Yusuf Al Idrus recounted the last contact he had with her.

"I was joking by saying that when she arrived in Pontianak we would eat satay together," he said.

"She contacted me via WhatsApp at 2.05pm with laughter. She was already boarding the plane and she said the weather were not good. I said pray a lot, please."

• Remittance charges will be tackled by blockchain

• UAE's monumental and risky Mars Mission to inspire future generations, says minister

• Could the UAE drive India's economy?

• News has a bright future and the UAE is at the heart of it

• Architecture is over - here's cybertecture

• The National announces Future of News journalism competition

• Round up: Experts share their visions of the world to come