The 28-year-old Argentine striker is one of two people still missing after contact was lost with the light aircraft he was travelling in on Monday night.
Police on the British island of Guernsey have suspended their search for the evening and warned chances of survival were “slim” if the aircraft landed on water.
Sala was on his way to the Welsh capital to train with his new teammates for the first time after completing a £15 million ($19 million) move to Cardiff from French side Nantes on Saturday.
The arrival of a player who had scored 12 goals in Ligue 1 this season was a beacon of hope for fans optimistic that his firepower could save their struggling side from relegation this season.
But excitement gave way to foreboding as fans laid flowers and heartfelt messages at Cardiff City Stadium.
Numbed and shocked supporters stood together in the club car park, where some laid daffodils and blue and white club scarves.
“The excitement of a new signing arriving at your club can bring so much happiness. That’s how we felt about Sala,” said Cardiff fan Josh Thomas, 24.
“He was the one who was going to turn our fortunes around and score the goals that would keep us up. He was going to be the one adored by the fans, including me. But within a few hours so much has changed.”
– ‘Difficult to absorb’ –
Sala was one of the top three goalscorers in France this season, which “just showed what a talented player we were signing and what he was to bring to the club”, Thomas said.
“All we can do is hope for the best.”
Keith Morgan, chairman of the Cardiff City Supporters Trust, had also been thrilled at the prospect of Sala joining the club he has supported for 50 years.
“As with any tragedy it’s difficult to absorb,” he said. “We’re obviously still hoping it’s not confirmed but when or if it is, we will contact Nantes offering all our help.”
Morgan said fans from “the wider football community” have been getting in touch to offer their sympathies and support to the club.
“I think fans realise what’s important and things like this put everything into perspective. Football is important in all our lives but not more than a person’s life,” he said. “It’s very sad.”
Cardiff have already had to deal with the aftermath of an air accident this season, being the first club to play Leicester City after a helicopter crash killed their owner and four others in October.
The club’s players were informed of the news at the training ground on Tuesday morning and the management decided to cancel their planned schedule.
“We made the decision first thing this morning to call off training with the thoughts of the squad, management, staff and the entire club are with Emiliano and the pilot,” the club’s chief executive Ken Choo said in a statement.
“All of us at Cardiff City FC would like to thank our fans, and the entire footballing family for their support at this difficult time. We continue to pray for positive news.”
It is expected that Cardiff’s players — who are not due to play again until January 29 when they visit Arsenal — will return to training on Wednesday morning.