Authorities have launched an investigation after a Thai Airways jet flew too low over central Melbourne, an action similar to the two incidents which led to Tiger Airways being grounded.

The Boeing 777-3D7, carrying passengers from Bangkok, descended below the minimum permitted altitude, about 11km south of Melbourne Airport, just at 8:19 p.m. (AEST) on July 24, according to Australian Transport Safety Bureau (ATSB) data.

It is understood the aircraft flew at about 1000 feet over the suburb of Sunshine North, when the permitted height was just under 2000 feet.

"During the approach, the aircraft descended below minimum altitude. The investigation is continuing," the ATSB said in a part-summary of its investigation so far.

It called it a "serious incident".

The 777-3D7 went on to land safely at Melbourne Airport a short time later.

The incident follows a decision by the Civil Aviation Safety Authority to ground all Tiger Airways flights on July 1 after two of its jets breached safe altitude limits.

A Tiger Airways flight flew too low without permission as it approached Avalon Airport, near Melbourne, on June 30.

An earlier investigation into a Tiger Airways aircraft landing at Melbourne Airport on June 7 found the flight approached at 2000 feet, instead of the minimum 2500 feet.

A directions hearing is scheduled in the Federal Court in Melbourne on Thursday regarding Tiger Airways resuming flights.

Comment is being sought from Thai Airways.