Three investigating judges have been appointed to examine the transfer of the Monaco to Nice Airport helicopter shuttle franchise five years ago.
Long-time licence holder Heli Air Monaco had called for an investigation after the franchise was awarded to Monacair in 2015.
Heli Air had operated the route for many years, starting in 1976 with just one aircraft. By 1984, the number of passengers on the shuttle service rose to 40,000 per year, and by 2008 the number had grown to 100,000 with a fleet of 12 helicopters.
After the loss of the route to Monacair, Heli Air Monaco has operated flights to other destinations from the Fontvieille heliport, plus sightseeing rides.
Separately, Monacair is currently in talks with its employees and the Government over redundancy terms for 32 of its 76 employees. The majority shareholders in Monacair are Andrea and Pierre Casiraghi, sons of its founder, Stefano.