Australia's Civil Aviation Safety Authority says the plane that crashed into the Swan River during the Perth Skyshow on Thursday was not approved to fly below 500 feet.
Pilot Peter Lynch and his passenger and partner Endah Cakrawati died when the plane crashed into the Swan River during the City of Perth's annual Australia Day event.
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Two dead after plane crashes into Swan River
Two people have died after a plane crashed into Perth's Swan River in front of thousands of people gathered for the Australia Day Skyworks display. Vision courtesy Seven News.
The seaplane stalled and nose-dived into the water about 5pm, breaking up on impact, as revellers looked on in horror.
In a statement to WAtoday, CASA said Mr Lynch's aircraft was operating as part of an approved air display, which was given special permission to operate.
"All aircraft operating as part of the air display sought and received approval from the Civil Aviation Safety Authority to do so," CASA said in the statement.
"Under the regulations, except during take-off and landing, or where specifically approved as part of the program of events, the minimum height at which any aircraft may operate is 500 feet above ground level.
"Air displays over built up (suburban) areas, public gatherings and vessels on the surface of a body of water are not normally approved."
Investigators are working to determine what led to the plane crashing, with two efforts running simultaneously - one spearheaded by WA police and another being coordinated by the Australian Transport Safety Bureau (ATSB).
![Safety authorites will inspect the plane on Friday, which is still in the Swan River.](/web/20170129191041im_/http://www.watoday.com.au/content/dam/images/g/t/z/k/t/m/image.related.articleLeadwide.620x349.gu0120.png/1485552270547.jpg)
Police will concentrate on determining the cause of death while the ATSB will look at air safety and technical issues, though both investigations will overlap.
ATSB investigators are currently at the crash site and will spend the next few days examining the scene, interviewing witnesses, and collecting maintenance and pilot records and air traffic control data.
![The recovery operation has begun.](/web/20170129191041im_/http://www.watoday.com.au/content/dam/images/g/u/0/e/o/d/image.related.articleLeadwide.620x349.gu0120.png/1485510874237.jpg)
A recovery operation is now underway - footage from 9 News Perth shows workers on a barge using a crane to secure larger parts of the wreckage, with divers in the water.
A recovery mission is underway at the Swan River following the Australia Day plane crash. An update in 9 News Perth at 6pm. pic.twitter.com/kmMNjW7s3J
— Nine News Perth (@9NewsPerth) January 27, 2017
![Endah Cakrawati, 30, and pilot Peter Lynch died after the plane crashed into the Swan River.](/web/20170129191041im_/http://www.watoday.com.au/content/dam/images/g/t/z/t/q/s/image.related.articleLeadNarrow.300x0.gu0120.png/1485510874237.jpg)
Aviation investigations manager Greg Madden said on Friday the plane, which is under guard by a police vessel, is of an aircraft type that didn't appear to have a history of faults.
"We'll be certainly looking closely at the aircraft history but at this stage, there's nothing to indicate that there's a problem with the aircraft," Mr Madden told ABC radio.
He said the model was not required to have a flight data or cockpit voice recorder, but other recording devices may be on board. A preliminary update on the investigation is expected to be uploaded to the ATSB website in about 30 days.
The Grumman Mallard is a medium sized, twin-engined amphibious aircraft that was manufactured in the United States from 1946 to 1951.
It's still widely in use around the world, with Australia's Paspaley Group running a fleet of turbo-prop equipped Mallards, servicing the pearl farms which are at the core of its operations.
On its website, Paspaly said it has "an excellent safety record."
The bodies of Mr Lynch, 52, and his female passenger Ms Aricakrawati, 30, have been recovered from the Swan River, while the aircraft itself remains in situ in the water with investigators analysing the wreckage.
Various aviation sources say the Grumman Mallard can weigh around four tonnes, and acting Commissioner Brown said extracting the crashed aircraft from the middle of the Swan River will be a huge logistical exercise.
"There would be a lot of work to do on the remains of the plane and it could take up to six months for the results to be known," acting Commissioner Stephen Brown told Radio 6PR on Friday.
"We want it to come out as pristine as it can and we want to be able to recover all of the parts. And they might not just be in that immediate vicinity so that's going to take some time."
Acting Commissioner Brown said once the plane has been extracted from the water, comprehensive investigations could then begin at either a police or ATSB facility in Perth.
"That'll be conversations between our police forensic officers and the ATSB as to where the best place to house it is. And then we'll start that meticulous job of working through the wreckage," he said.
On its website, the Bureau lists the fatal incident as having an 'occurance type' of 'collision with terrain' with the aircraft listed as destroyed.
The ATSB is seeking to speak with witnesses and collect any video recordings that might assist its work.
Those who witnessed the crash in person requested to contact the ATSB on 1800 020 616 or email ATSBinfo@atsb.gov.au.
A final report on the incident from the ATSB is expected to be published within 12 months.