Air traffic controllers at Sydney airport have warned federal safety regulators they have “grave concerns” about changes to airspace rules introduced last month, likening the situation to the months leading up to a crash in Washington DC in which 67 people died.

Guardian Australia can reveal the federal government was notified on Thursday of a confidential complaint considered by the Australian Transport Safety Bureau (ATSB), in which an experienced air traffic controller warned in June that changes related to the new Western Sydney International airport had been rushed, with “inadequate training for controllers, of all experience levels”.

The complainant told the regulator a large group of controllers in Sydney “hold grave concerns about the project”, referring to the air traffic redesign to accommodate the new airport.

The revelations come in the wake of three safety incidents at Australia’s busiest airport, including a runway incursion that saw a Virgin plane forced to abort takeoff when a Qantas flight began to cross the runway in front of it earlier this month.

Only a few hours before that incident, a Jetstar flight narrowly avoided colliding with a Qatar Airways plane on the tarmac, prompting nationwide attention on the severe shortage of air traffic controllers.

Ahead of new airspace rules introduced in the Sydney Basin on 9 July, the confidential complaint warned air traffic controllers “have minimal confidence in their ability to handle the new airspace and procedures under normal traffic levels”.

The experienced air traffic controller warned there was already excessive pressure on the current system because of staff shortages, training and experience levels.

Controllers are being expected to learn about 1,000 pages of new training material without an adequate timetable, the whistleblower said.

“The reporter is concerned there are similarities to the (air traffic controller) situation in Washington whereby the controllers were pleading with their local management for changes to be made in the months leading up to the mid-air collision,” the ATSB said in its official response.

That is a reference to the January 2025 crash between an airliner preparing to land at Ronald Reagan airport and a Black Hawk helicopter. Sixty seven people were killed, making the incident the deadliest crash on American soil in more than two decades.

In December, the US government admitted the Federal Aviation Administration and the army played a role in causing the crash.

The ATSB report said the complainant was “concerned that with current pressure associated with staffing and experience levels, fast-tracked training along with the multiple complex procedural changes”, the Sydney Terminal Control Unit “is not ready to safely manage the new airspace changes as the training program currently stands”.

Responding to the complainant, the Sydney Terminal Control Unit said the individual “may or may not be across all the procedural or safety work that has occurred to this point”.

It said all the new training manuals and procedures associated with the changes had been carefully developed and approved, while extra staff supervision and monitoring was in place, and restrictions on new air traffic controllers working within the system was planned.

The federal regulator, the Civil Aviation Safety Authority (Casa), told the ATSB it was satisfied that Airservices Australia has implemented appropriate training, procedures, and operational support arrangements and promised sufficient oversight to maintain safety.

“Relevant procedures and training were developed and reviewed by operational subject matter experts, standards personnel, and project teams prior to implementation,” Casa said.

Travellers have faced lengthy delays due to incidents and longer-term problems stemming from a lack of air traffic controllers in Sydney.

A spokesperson for the federal transport minister, Catherine King, said it was appropriate Casa had responded to the ATSB report.

Notification to the federal government is the final step in the process.

Earlier this month, King said new and improved rostering practices would be put in place in September and that a new simulator had been installed to boost training capacity in Sydney.

King said six controllers were currently training, with another 15 expected to commence before the end of 2027.