Garuda pilot Marwoto Komar faces up to seven years' jail after Indonesian police laid charges over last year's Yogyakarta plane crash in which 21 people, including five Australians, died.

Police have been under intense pressure to speed up the criminal investigation into crash on March 7 when Garuda flight 200 from Jakarta overshot the runway.

A National Transportation Safety Committee report last October found that Captain Marwoto, 45, tried to land the Boeing 737-400 at twice the proper speed and ignored 15 automated cockpit warnings as he did so.

He also rejected frantic calls by his co-pilot, Gagam Saman Rahman, to perform a "go-around" at the last minute, which could have avoided the tragedy.

Under international air accident investigation guidelines, the findings in that report are not admissible in a criminal prosecution, meaning police have had to mount their own investigation into the matter.

February 4's interrogation was Captain Marwoto's fourth since the crash, although it was the first time he has officially been a suspect in the case.

In previous interviews, he has had the status of witness.

Captain Marwoto's lawyer, Mohammad Assegaf, warned that the charges laid against his client could have a drastic effect on the booming air transport industry, with other Indonesian pilots potentially refusing to fly.

"In the case of accidents at sea, the ship's captain or the master is not criminally investigated, but they go through a maritime court," he said.

"Why is this not being done in the case of air travel? There needs to be some thought given to the matter of dealing with mistakes in ... aviation - it should not be a criminal matter."

Criminology professor Rudi Satrio, of the University of Indonesia, rejected Mr Assegaf's call, saying "we don't have an aviation court, but it doesn't matter because this matter is already provided for in the criminal code".

Another lawyer for Captain Marwoto, Kamal Firdaus, said the pilot could face several separate charges, including for manslaughter and criminal negligence. However, the maximum jail penalty allowable on any of these charges is seven years, for criminal negligence causing death in an aviation matter.

Legal experts consulted by The Australian on February 4 said that under the Indonesian sentencing system, there would be no attempt to lay separate charges for each of the 21 deaths, meaning the seven-year penalty would be the maximum term served, should Captain Marwoto be found guilty.

Dr Satrio also said police would have the right to call an expert witness from the National Transportation Safety Committee (KNKT) once the trial was under way, as this would not breach the international convention on accident investigators remaining separate from police inquiries.

"Because this is an aviation matter, it's very specialised, so if the police do not have the full ability to investigate it, they will have to rely on an expert witness to determine the outcome," Dr Satrio said.

"That could be the (committee)."

Senior KNKT member Mardjono Siswo Swarno said that any member of the committee could be expected to be called to give evidence "as a citizen of the nation".

"But if someone is called, they will merely be called as an expert witness, since the KNKT report may not be used in the court," Mr Mardjono said.

Embassy official Liz O'Neill, AusAID officer Allison Sudradjat, Australian Federal Police officers Brice Steele and Mark Scott and The Australian Financial Review journalist Morgan Mellish died in the crash. The Sydney Morning Herald political reporter Cynthia Banham was seriously injured.