Malaysia Airlines has agreed to hand over corporate records and documents, it was previously desperate to keep secret, to families of MH370 victims.
The change of course came after the airline refused for more than a year to provide any records to assist compensation claims against it.
Flight MH370 had 239 people on board, including two New Zealanders, when it vanished in March 2014. It is presumed to have crashed into the southern Indian Ocean after veering off course.
Today's surprise development emerged during a Federal Court directions hearing in Sydney, Australia in a case involving the adult children of four MH370 passengers - Mary and Rod Burrows, and Cathy and Bob Lawton.
It is thought to be the most advanced of all court actions against Malaysia Airlines and the lead insurer, global aviation insurance heavyweight Allianz.
The agreement came as a total shock to the families' lawyer, aviation specialist John Dawson.
It is the realisation of a wish-list he has been hounding the airline for more than a year to produce.
The families hope the documents will assist and even speed up their claims for damages well beyond the offer that is on the table.
ABC reported that Allianz was offering payments capped at A$250,000 (NZ$266,000) for each Australian victim.
Payments of NZ$53,000 per passenger were made more than a year ago in line with the Montreal Treaty, which sets out the broad obligations of airlines and insurers.
But relatives are setting their sights far higher, hoping the document trove promised by the carrier may contain evidence of incompetency and failures that further their cause.
For that reason alone, the potential significance of the changed attitude to releasing documents is not fully understood.
Allianz Australia spokesman Nicholas Schofield would say only this:
"AGCS can confirm its position as lead reinsurer for the aviation hull and liability coverage.
"The loss of flight MH370 is clearly an exceptional event but, as with all claims, we cannot comment on the details of this case, particularly in relation to matters that are before the courts."
The documents include:
- The most recent medical certificate held by each member of the flight crew, including both cockpit crew and cabin crew
- The most recent pilots licence held by the crew
- Any operational notes logs or records held by the airline in relation to the flight
- Procedures for carrying dangerous goods
- Procedures for loss of radio contact, flying over oceans, and what to do in the event of hijacking
- The operations manual for the plane, including flight deck security
- The flight plan lodged by the captain with air traffic control
For any other aircraft it is a mundane list - but when its MH370, anything and everything that sheds new light, no mater how dim, is welcome news.
For the families, it will be the first real chance to peer inside the now defunct Malaysia Airlines business.
The compensation case is, in any case, a proxy that names the airline for culpability but in reality chases the insurer Allianz for the money.
In the arcane world of aviation law, Malaysia Airlines received a massive windfall from the tragedy.
Allianz is almost all that is legally left of the carrier - the entity flying the brand now by the same name, Malaysia Airlines Berhad, is a legal phoenix that insists it has no legal obligations to the relatives.
An act of parliament in 2015 engineered all that, and it remains to be seen whether Malaysia's judicial system allows the act to stand, or instead cuts down what lawyers and relatives decry as a sham legal fiction manufactured by the Malaysian Government to try to shield the carrier.
It is unclear whether the documents promised to the lawyers will get a public airing - that would occur only if and when the case reaches the trial stage.
The next directions hearing in the case is not scheduled until next March, so one small victory in process is no real guarantee of success in the compensation battle.
Swings and roundabouts for family members
The maintenance log books of the Boeing 777 and medical and personnel records of the captain and co-pilot will be exposed to the lawyers.
The airline has also acknowledged for the first time that it will have to deal with compensation claims from the families of those aboard the missing plane.
"I don't sleep a lot", said Karla McMaster, 29, who along with a number of family members of MH370 victims, now suffers with post-traumatic shock.
That condition is also part of the claim against the carrier, which informed next of kin that their loved ones were dead by text message.
It is an unusual move to claim for psychological injuries among the surviving relatives, but not without precedent - normally airlines and their insurers pay only for bodily injury to passengers.
But Ms McMaster was worried it could take another year of stonewall talks before a trial could take place.
To her mind, justice is still being delayed and denied.
"I can't remember the last time they offered me any support," she said.