Tauranga-based airline Sunair Aviation has been grounded by the Civil Aviation Authority for the second time in nine months.
The authority suspended Sunair's Air Operator Certificate, along with the Certificate of Airworthiness for the Sun Air fleet, on September 8.
A spokeswoman for the authority said the action would ground the Sunair fleet and suspend all Sunair flight operations for an initial 10-day period.
"An investigation into the company by the CAA is continuing," she said.
When asked exactly what they were investigating, what concerns prompted the investigation and when it began, the spokeswoman said the authority could not comment on the investigation.
On December 6 Sunair Aviation Ltd's Air Operator Certificate was suspended for 10 days, and reissued on December 16.
Sunair chief executive Daniel Power said that the authority had "concerns with the company" and had suspended Sunair's Air Operator Certificate while it investigated the concerns.
"We hope to have these matters dealt with quickly, allowing a speedy return to the safe operation Sunair has provided for the past 30 years."
A Bay of Plenty man who said he was a regular Sunair customer said he got one day's notice that his flights had been cancelled.
He asked around and heard the company had been grounded by the Civil Aviation Authority.
"Obviously I'm pretty dissatisfied. I've flown with them before because it's a convenience but I'm seriously considering the larger operators because this is just inconvenient."
In March this year, Sunair Aviation became the first regional non-jet operator in the North Island to be selected as a preferred air carrier on the All of Government panel.
The airline tendered for the panel in 2016 and, after an exhaustive process, was advised that its application had succeeded. The new status became effective from the beginning of March 2017 to begin carrying government personnel.