An access road is being built to enable vehicles to reach the site of the Germanwings plane crash in the Alps.
The road could be finished as early as tomorrow evening.
Forensics teams searching the mountainside still have not found the second black box - the flight data recorder.
Sky's Jonathan Samuels, in Dusseldorf, says the co-pilot who crashed the Airbus - Andreas Lubitz - may have had problems with his eyesight:
The captain of the jet that crashed in the French Alps reportedly screamed at his co-pilot to "open the damn door" as he tried to get in the cockpit.
Andreas Lubitz, 27, apparently locked the captain out of the cabin and deliberately flew the Germanwings jet into a mountain, killing 150 people.
The older pilot left to use the toilet and then desperately tried to open the cockpit door during Flight 4U 9525's eight-minute descent, according to the black box voice recorder.
Germany's Bild on Sunday newspaper said he is heard shouting: "For God's sake, open the door!" as passengers scream in the background.
He then tries to smash through the heavily-reinforced door with an axe, while yelling at a silent Lubitz to "open the damn door".
Before leaving the cockpit, the captain is heard telling Lubitz he did not have time to go to the toilet before they left Barcelona for Dusseldorf.
German prosecutors believe Lubitz hid an illness from his airline, and had been written off sick on the day of the crash.
He had also sought treatment for vision problems which could have threatened his career, officials told the New York Times.
The Dusseldorf University Hospital said Lubitz had been evaluated at its clinic in February and on 10 March. The hospital has an eye clinic, but it did not comment on why he was being treated citing patient privacy laws.
Police found medicines for treating psychological conditions during searches at his home in Dusseldorf, according to German newspaper Welt am Sonntag.
And Lubitz's ex-girlfriend, Maria W, has claimed he told her: "One day I'm going to do something that will change the whole system, and everyone will know my name and remember."
She told Bild if he did deliberately crash the plane, it was "because he understood that because of his health problems, his big dream of a job at Lufthansa, of a job as captain and as a long-haul pilot was practically impossible".
French police investigator Jean-Pierre Michel has said Lubitz's personality was a "serious lead" in the investigation, but not the only one.
Investigation continues
Meanwhile, a father of one of the three British victims called for airlines to do more to look after their pilots.
"I believe the airlines should be more transparent and our finest pilots looked after properly. We put our lives and our children's lives in their hands," said Phillip Bramley, whose son Paul, 28, died in the disaster.
Mr Bramley said the co-pilot's motive for crashing the plane is "not relevant", and added his focus was on seeing "this never happens again".
Police chief Jean-Pierre Michel, speaking to AFP news agency in Dusseldorf, said: "We have a certain number of elements which allow us to make progress on this lead, which is a serious lead but which can't be the only one."
He added that the investigation has not revealed a "particular element" in Lubitz's life which could explain his alleged actions.
German prosecutors revealed on Friday that several sick notes were found during searches of his home and that of his parents in Montabaur.
The prosecutors' office said: "Documents with medical contents were confiscated that point towards an existing illness and corresponding treatment by doctors.
"The fact there are sick notes saying he was unable to work, among other things, that were found torn up, which were recent and even from the day of the crime, support the assumption based on the preliminary examination that the deceased hid his illness from his employer and his professional colleagues."
Germanwings confirmed the sick note for the day of the crash was not submitted to the company.
Operations to recover the remains of those killed in the Col de Mariaud are expected to last for some time.
Rescue crews are having to be winched down the steep mountainside from helicopters.
Much of the wreckage is smaller than a car door, and because the crash site is steep crucial pieces of evidence are sliding down scree slopes.
Colonel Patrick Touron, one of France's leading forensic investigators, said: "We have not found a single body intact. DNA will be the determining element that will lead to identification."
Up to 600 "biological elements" have been recovered and are being cross-referenced to try and identify victims.
Originally posted at 7.51am
