A former Garuda Indonesia pilot charged with crashing the plane which killed 21 people including 5 Australians in March last year says it would have been impossible for him to have done it deliberately.

The pilot pleaded not guilty in court in Yogjakarta as Indonesia Correspondent Geoff Thompson reports.

With tears in his eyes and with a trembling voice, Marwoto Komar told a court in Yogjakarta that with 22 years of experience as a pilot, it would be impossible for him deliberately crash the plane.

Appearing for the second time in his pilot's uniform, he said that he had no intention of carelessly harming the passengers.

An air safety investigation report found that Komar ignored 15 automated warnings and the pleas of his co-pilot when attempted to land the Garuda flight at almost twice the normal speed on March 7 last year.