The West Australian coroner has found the deaths of more than 100 asylum seekers whose boat sank last year were an accident, but that more could be done by Australian and Indonesian authorities to prevent such tragedies.

The boat was carrying more than 200 people when it capsized 200 kilometres south of Indonesia in June 2012.

Coroner Alastair Hope was investigating whether swifter action by the two countries could have prevented the disaster.

On Wednesday, Mr Hope said communication between the Indonesian and Australian authorities was inadequate once Indonesian authorities took over the search.

He also said people smugglers contributed to the death of the asylum seekers, saying they acted with callous indifference.

Key points Coroner hands down findings into asylum boat tragedy that killed more than 100 people in June last year

Coroner hands down findings into asylum boat tragedy that killed more than 100 people in June last year Coroner found communication between Australian and Indonesian authorities was inadequate

Coroner found communication between Australian and Indonesian authorities was inadequate The findings reveal the Australian Maritime Safety Authority (AMSA) could have been more proactive

The findings reveal the Australian Maritime Safety Authority (AMSA) could have been more proactive AMSA told the inquiry it takes distress calls seriously and it manages 8,000 incidents a year

During the inquest, the Australian Maritime Safety Authority (AMSA) rejected suggestions it did not respond adequately to a distress call.

A report, prepared by a number of agencies including Australian Customs and Border Protection, was tabled at the inquest pointing to a number of actions AMSA could have taken.

It says it could have made an emergency broadcast to shipping in the area to go to the aid of the boat, it could have been more proactive in remaining in contact with the boat, and it could have used a telecommunications provider to help locate it.

In a statement, AMSA said it acknowledged the coroner's findings.

"AMSA has fully assisted the WA Police inquiry and coronial inquest and a considered response to the coroner's recommendations will be presented in due course," the statement said.

Distress calls to AMSA replayed to inquest

Those on board made dozens of calls to AMSA's Rescue Coordination Centre to tell them they needed help but operators struggled to hear them above wind noise.

The calls were replayed to the inquest.

"I cannot hear you, you need to get out of the wind, you need to get away from the wind," the call operator said.

The centre told the boat to turn back and passed responsibility for the search to Indonesia.

Under questioning, AMSA's Alan Lloyd strongly rebutted claims the agency did not respond adequately when it received distress calls about the boat.

He told the court the authority had not determined if the calls were genuine.

"We want to be reasonably confident that a vessel is in distress before we issue an emergency broadcast," he said.

"We have to confirm they are telling us an accurate story, it was an ongoing assessment and we were still in the gathering information phase."

Mr Lloyd told the inquest AMSA took asylum seeker distress calls seriously, the agency managed 8,000 incidents a year and had a 99.6 per cent success rate.

Survivor gave evidence of final moments before capsize

Australia eventually took over the rescue when an Australian plane spotted the capsized boat, more than 30 hours after the initial call for help.

A survivor from Pakistan gave evidence of the final moments when the boat filled with water, lost power and capsized.

Appearing via videolink from Melbourne, the man said people were crammed on the deck of the overcrowded boat.

A person told him that the boat had a lot of water in it and he said he suddenly found himself in the ocean and could hear people crying "God" and "mother".

The survivor said he has found it very hard for him to forget the accident.

Asked if Indonesia and Australia interacted so each knew what search and rescue resources the other had available, Mr Lloyd replied "on a daily basis, no".

He said AMSA had a strategic understanding only.