A confidential report to Tigerair management shows the crew responsible for a March 3 Airbus A320 flight carrying 177 people from Sydney to Perth were given a highly inaccurate flight plan that could have resulted in the aircraft not having enough fuel to make the journey.

The plan, which allegedly was given late to the flight crew, advised that the plane was carrying zero passengers and, as such, required less fuel than it actually needed to get to Perth. “This meant that all the supplied flight plan calculations were based on a flight 14,660kgs lighter than the actual aircraft weight,” the April 1 report found.

The pilots detected the mistake, loaded extra fuel before take-off and landed safely in Perth.

However, Tigerair and the Australian Transport Safety Bureau have launched investigations into the incident, with particular emphasis on disputed accounts about whether the extra fuel loaded by the pilots met minimum safety standards.

Fairfax Media can reveal:

The dispatcher responsible for the erroneous Sydney-Perth flight plan told an internal Tigerair investigation that he had been trained at a time when only 20 plans a day were needed, but was now preparing as many as 80 plans per day. “Additionally, he stated his training on some aspects of the flight planning system was minimal and amounted to being shown ‘3 or 4’ times how to run a plan by another dispatcher,” the Tigerair report found.

A July 23 Tigerair safety bulletin documented how an Airbus A320 filled with passengers encountered “rapidly deteriorating safety margins” after parts of the hydro-tow bar used to push the aircraft back from a gate at Melbourne airport became disconnected and collided with the right engine cowling. The pilots had no knowledge of the potentially dangerous incident because “all effective communication was... lost" with the ground crew and “the flight crew only became aware of the abnormal situation due to the nose wheel ‘shuddering’".

Tensions between Tiger flight crews and staff on the ground prompting Tiger chief pilot Harry Holling to last month email all pilots to warn them about “several reports lately of crew having heated discussions with other staff whilst on line’’. “There is no place for yelling, aggressive or threatening behaviour…this applies to radio transmissions as well as face to face communication.”

Tigerair is 60 per cent owned by Virgin Australia. In 2011, the airline was grounded for a short period by the Civil Aviation Safety Authority after a series of adverse safety incidents. At that time, it was associated with Singapore Airlines.

In a statement on Friday, Tigerair said the March 3 Sydney to Perth flight was reported to the ATSB as a routine incident.

"Tigerair advises it is satisfied that at all times the aircraft had more than adequate fuel for the journey and landed in Perth without incident with more than legal fuel reserves," Tigerair's statement said. "As the incident is currently under review by the ATSB, it's not appropriate for the airline to comment further at this time."

It is understood that although the aircraft landed with enough fuel in reserve to meet CASA's requirements, it may not have been sufficient to meet the airline's minimum standards.

Shortly after the March 3 flight plan incident, Mr Holling sent an email to all pilots warning them to check flight plans for mistakes.

"As pilots, we are the last line of defence and we should all exercise extra care when our flights are disrupted or not routine. Generally everyone does a great job in dealing with the pressures of low cost carrier operations and dealing with weather and curfews," Mr Holling wrote.

The recent collision between the hydro-tow bar and the Tigerair plane has raised questions about the communication links between the cockpit, flight dispatchers and the tug operators.

The Tigerair safety bulletin reveals that the tug driver has no “verbal link” with the flight crew or dispatcher. “In this occurrence the dispatcher perceived a dangerous situation was rapidly developing and discarded the headset in order to remove himself from the path of the advancing aircraft. A stop instruction was not issued to the flight crew.”

Tigerair management reported the collision to the ATSB, which decided not to investigate further. Tigerair is conducting its own inquiry into the incident.

The captain responsible for the March 3 Sydney to Perth flight was stood down after he reported the erroneous flight plan. He decided to load extra fuel and did not request a new flight plan because he risked missing the Sydney airport 10pm curfew.

Shortly after reporting the flight plan error, the captain's medical certificate was suspended after an anonymous allegation was made to Tiger, Virgin Australia and the Civil Aviation Safety Authority accusing him of cocaine use.

The captain, who is understood to strenuously deny the allegation, had three months earlier passed drug and alcohol tests.

A CASA spokesman said it was standard procedure to suspend the medical certificate of any pilot accused of drug use until another drug test was conducted.

Tiger confirmed that the captain and his first officer were stood down after the Sydney to Perth flight. The airline said this was standard procedure to enable both to assist the investigations.

The first officer has returned duties at Tigerair and the airline is understood to have asked the captain to return once he complies with CASA's requirements to reinstate his medical certificate.

Attempts by the captain to find out the source of the drug allegation have been unsuccessful, with CASA refusing to disclose whether it was someone in Tigerair management or elsewhere responsible.

CASA has refused a freedom of information request lodged by the captain for all documents regarding the drug use allegations because it would involve an “unreasonable disclosure” of personal information about the source of the complaint.

CASA also said release of information could harm Tiger’s business affairs and affect its ability to enforce aviation safety laws.

The ATSB report into the Sydney to Perth flight is due in October.

Know more? rbaker@fairfaxmedia.com.au