The light aircraft was travelling from Nantes in France to Cardiff in Wales, confirmed Air Traffic Control, when it disappeared from radar around 20 kilometres north of the island of Guernsey in the Channel.
Concerns were raised after 28-year-old Sala was unresponsive to messages on social media.
The Argentinian forward became Cardiff's record transfer at £15 million ($27m) when he signed for the Bluebirds on Sunday (AEDT) on a three-and-a-half year deal from French Ligue 1 side Nantes.
He scored 12 goals in 19 league games this season for Nantes to earn the Premier league move.
Cardiff City told Sky News they are seeking confirmation over reports their new attacker was on board, while AAP say French police sources confirm that he was.
Guernsey Police issued a statement, saying: "Guernsey Coastguard received an alert at 20:23 from Jersey ATC, that a light aircraft had gone off their radar approximately 15 miles north of Guernsey, initiating a major search and rescue operation involving both St Peter Port and Alderney lifeboats.
"Air Search 1 and 2 HM Coastguard helicopters are also involved in the search.
"The PA 46 Malibu, a single turbine engine aircraft was on route from Nantes in France, to Cardiff in Wales, with two people on board when it was lost off radar as Jersey ATC was attempting to make contact.
"A search model was created on SARIS, based on the likely ditching position, and all search and rescue assets were tasked to the area.
"The search was terminated at 02:00, with all search and rescue assets being stood down, due to strengthening winds, worsening sea conditions and reducing visibility.
"At this time no trace of the missing aircraft had been found.
"The aircraft departed Nantes at 1915 for Cardiff. The aircraft was flying at 5000 feet. The aircraft on passing Guernsey requested descent. Jersey ATC lost contact whilst it was flying at 2300 feet.
"Air Search 1 and a French rescue helicopter based in Cherbourg, resumed the search of the area at 08:00."
