On November 11, 1975 the Brazilian Federal Government created the Brazilian Integrated System of Regional Air Transportation and divided the country in five different regions, for which five newly created regional airlines received a concession to operate air services. RIO-SUL Serviços Aéreos Regionais S/A was the fourth of those regional airlines to be made operational. Founded on August 24, 1976, Rio Sul had its services start on September 8, 1976. Its operational area comprised roughly the Southern and parts of the Southeastregions of Brazil, specifically the states of Rio Grande do Sul, Santa Catarina, Paraná, Rio de Janeiro, and parts of São Paulo, and Espírito Santo. The airline was originally formed by Top Táxi Aéreo, Bradesco Bank, Atlântica-Boavista Insurance, and Varig. In 1992 the National Conference of Civil Aviation abolished the geographical division of the country and allowed further expansion in national and regional routes, prompting Rio Sul to acquire Nordeste Linhas Aéreas Regionais in 1995. It was then owned by Varig Participações em Transportes Aéreos. In 2002 the administration of Rio Sul were merged with Varig. The brand Rio Sul was part of the assets sold as VRG Linhas Aéreas although its debts remained under the judicial entity Viação Aérea Rio-Grandense, which uses the brand name Flex Linhas Aéreas. As a result of accumulated debts around BRL10 billion, on August 20, 2010, at the request of the administrator, the 1st Business Court of Rio de Janeiro declared Flex, which included remaining assets of Rio-Sul, bankrupt and initiated the process of liquidation.
According to the Aviation Safety Network's database, Rio Sul Serviços Aéreos Regionais has never experienced a fatal accident in its 26-year-history, though four hull-losses have occurred:
On August 6, 1984, a Fokker F27 Friendship over shot the runway at Santos Dumont Airport. All seven occupants survived, but the aircraft was damaged beyond repair and written off.
On July 25, 1987, an Embraer EMB 110 Bandeirante overshot the runway at Santo Angelo Airport. All 13 passengers and crew survived, but the aircraft was damaged beyond repair and written off.
On December 29, 1998, Rio Sul Flight 310, an Embraer ERJ-145, was damaged beyond repair when it made a hard landing at Afonso Pena International Airport. All 40 passengers and crew on board survived. Investigators determined that engine power had been reduced just before landing. The aircraft was written off.
On December 17, 2001, a Boeing 737-500 operating a scheduled passenger flight from Rio de Janeiro to Belo Horizonte undershot runway 16 at Tancredo Neves International Airport by as a result of adverse weather conditions. There were no fatalities. Despite substantial damage, the aircraft was repaired and returned to service. However, nearly 12 years later, exactly the same aircraft would crash in Russia, killing everyone on board.
