Emiliano Sala's sister has appealed for police to keep looking for the missing Cardiff City striker after the official search was called off.
Guernsey Police announced an end to the search, which began on Monday, saying the chances of survival were "extremely remote".
Sala's former club Nantes reacted with anger at the decision to formally call off the search for his missing plane and demanded it be resumed.
Sala's sister Romina also appealed to authorities to continue looking for him, saying he is a "fighter".
She said: "Please don't stop the search. We appreciate the effort but please don't stop the search.
"At the bottom of my heart I know Emiliano is a fighter and he and the pilot are somewhere in the middle of the Channel. They are not going to give up so please don't stop the search."
Romina Sala is understood to have met agent Mark McKay, who was representing Nantes in the transfer, in Cardiff on Thursday and was shown WhatsApp messages sent from Emiliano to McKay's brother Jack in the preceding days, in which the player expressed how happy he was.
Her emotional plea came after Harbour Master Captain David Barker released a statement which said: "My team have just met to review the search and rescue operation which has been underway since the plane disappeared on Monday night.
"Despite the best efforts of air and search assets from the Channel Islands, UK and France, which has covered an area of approximately 1,700sq miles - with a significant amount of this searched more than once - and having examined mobile phone data and satellite imagery, we have been unable to find any trace of the aircraft, the pilot or the passenger.
"We reviewed all the info available to us, as well as knowing what emergency equipment was on board, and have taken the difficult decision to end the search.
"The chances of survival at this stage are extremely remote. Next of kin have been informed of this development, and my thoughts go out to the family of the pilot at this difficult time."
He added his thanks to all those involved in the search and said although everyone on the final aircraft has returned to the UK, the incident remains open.
Vessels and aircraft in the area will be asked to keep a lookout for any trace of the plane, a request which Mr Barker said would "continue indefinitely".
Cardiff said in a statement on Thursday evening: "At this time of immeasurable sadness, our thoughts are with the family and friends of both men on board, the fans of both FC Nantes, Cardiff City, and their connections around the world."
The club's owner Vincent Tan added: "Monday evening's news shook everyone at Cardiff City FC to the core.
"We were looking forward to providing Emiliano with the next step in his life and career. Those who met Emiliano described a good-natured and humble young man who was eager to impress in the Premier League.
"The response from the football community has been truly touching and we place on record our sincere thanks to those who have sent messages of support. We also thank everyone involved with the search and rescue operation, and continue to pray for Emiliano, David Ibbotson and their families."