French investigators will on Sunday publish their final crash report on the Germanwings plane deliberately flown into a French mountainside by its co-pilot in a tragedy that raised unprecedented safety questions.
The BEA civil aviation investigators are primarily expected to make recommendations on the locking of cockpit doors during flights.
As a result of the Germanwings crash a year ago -- in which 150 people travelling between Barcelona and Duesseldorf died -- European aviation authorities have already recommended making it compulsory to have two people in the cockpit at any time during flights.
Some countries are opposed to the measure, however, with Germany's pilots' union believing it poses "risks that outweigh any supposed improvements in security".
In the fateful flight on March 24, 2015, co-pilot Andreas Lubitz locked the pilot out of the cockpit. Ten minutes later the Airbus 320 ploughed into a mountain hillside, killing all 144 passengers and six crew.
It emerged that Lubitz had been suffering from depression and had seen dozens of doctors in the years preceding the crash.
But under German law none was able to alert his employers to his state of mind and he was allowed to continue flying.
On the black box voice recorder recovered at the crash scene, all that is heard from Lubitz is regular breathing. He gave no words of explanation for his murderous course of action.
The European Aviation Safety Agency (Easa) has already recommended stepping up medical testing for pilots, including more psychological tests.
BEA chief Remi Jouty said the French investigation had sought to identify the "systematic failures which led to this accident". The investigators had also looked at the "balance between medical secrecy and flight security".
The dead included 72 Germans, including a group of 16 high school students, and 50 Spaniards.
A German lawyer for some of the families of the dead said this month they intended to sue the training school in Phoenix, Arizona, which Lubitz attended, claiming it should have flagged up his psychological problems.
"The co-pilot interrupted his training there for a while due to psychological problems," lawyer Christof Wellens said. "He shouldn't have been allowed to resume his training."
Germanwings' parent company Lufthansa has paid 50,000 euros ($56,000) per victim in an initial payment and offered an additional 25,000 euros to each of the families plus 10,000 euros to each immediate relative including parents, children and spouse.