The CEO of Real Tonga airlines, Tevita Palu, says the hold up is due to a failure of the government to complete aircraft certification documentation.
Mr Palu still hopes the operation will resume later this month after an almost two-year suspension.
He says his company paid about 185,000 US dollars for three pilots from China and Australia to operate the MA60 aircraft, for its insurance and other technical needs.
However Radio Tonga reports the pilots had to return to their respective countries because of the uncertainty of the aircraft's operation.
The 56-seater was gifted by China in 2013, flew domestically in August of that year before the New Zealand government objected, calling for the MA60 to be certified by an international recognised certification authority, suspending some aid and issuing a travel advisory for Tonga over safety concerns.
Real Tonga has a four-year contract with the Tongan government to operate the aircraft.