17:50 - That rounds up our coverage on day two of what has been ranked as one of France's worst air disasters of all time.
Scroll down to find out more about the visits and press conferences of President Hollande, Chancellor Merkel, and Prime Minister Rajoy, as well as the comments from the French authority responsible for safety investigations in aviation - which is leading the technical probe into the crash.
Click here to see a timeline of the two days in pictures and here to read everything we know so far.
Read our interview with an aviation safety expert here, and click here to understand why the black box holds the key to the mystery crash.
(President Hollande, German Chancellor Angela Merkel, and Spain's PM Mariano Rajoy. Photo: AFP)
17:37 - No reason to say why lack of contact
"At this stage, clearly, we are not in a position to have the slightest explanation or interpretation on the reasons that could have led this plane to descend... or the reasons why it did not respond to attempts to contact it by air traffic controllers," said Remi Jouty, head of French air crash investigation agency BEA.
17:33 - 'Too early to tell if accident'
The press conference by investigators from BEA continues with director Remi Jouty saying it's too early to say whether it was an accident or whether there was any intentional interference. He confirms that weather conditions in the area were not extreme.
They will go ahead with a transcription of the audio file.
17:30 - Last contact a routine call
The last contact between plane and air traffic control was a routine call to confirm the route that the plane would take. Around a minute or so later the aircraft started to descend and continued to do so until it hit the mountain.
The plane was followed on the radar almost until the moment of impact.
17:25 - "No explanation so far for crash"
Chief air investigator Remi Jouty says at this stage they still cannot explain why the plane might have crashed. He says no theory is being ruled out at this stage, including that of a possible terrorist attack.
(Remi Jouty at the press conference. Photo: BFM TV screengrab)
17:22 - Air investigators 'optimistic'
The BEA press conference continues with director Remi Jouty saying they are optimistic about the investigation given that they have obtained a "usable audio file" from the black box.
Jouty says investigators have listened to the file once and confirms voices can be heard, but refuses to divulge anymore information. He says its not been possible to tell who the voices belong too.
17:20 - Investigators: 'usable audio file' extracted from Germanwings black box
French air investigators from BEA says they have managed to obtain an audio file from the damaged black box that is “usable”.
But they said they haven’t been able to fully analyse the recording as of yet.
At the press conference the BEA representative is batting away further questions about the content of the audio data, saying it is still too early at this stage to draw any conclusions.
17:11 - Hollande confirms casing of second black box recovered
French President Francois Hollande said Wednesday the casing for the second black box from the Germanwings Airbus crash had been found in the French Alps, but not the box itself.
"We're looking for a second black box. Its casing has been found, but not yet, unfortunately, the box itself," he said at a news conference near the crash site, alongside German Chancellor Angela Merkel and Spanish Prime Minister Mariano Rajoy.
17:00 - Merkel offers condolences
German Chancellor Angela Merkel has written in a book of condolences that have been opened at Seyne-Les-Alps near the scene of the crash.
"My deepest sympathies with the families and all my thanks for the friendship of the people of this region and in France," she wrote.
For his part Hollande wrote: "Tribute to the victims. Support to the families."
16:58 - Crash site 'off limits' for two weeks
Meanwhile the mayor of Vernet, the nearest town to the crash scene, has announced that no one will be allowed access to the crash scene for "the next two weeks", reported French television channel i-Télé.
16:57- Hollande says "we owe it to the families"
The French president is giving a press conference alongside Angela Merkel and Mariano Rajoy.
"We are here in memory of the victims," he told reporters.
"One hundred and fifty people died in this terrible disaster. Children, pupils, entire families, not to mention the crew. I speak on behalf of France, Angela Merkel and Mariano Rajoy in sharing out most sincere condolences. France is by your side in these times, as it is with all affected countries affected by this ordeal."
(Photo: Screengrab - BFM TV)
"I want to salute all the emergency services who have been mobilized since the alert of the crash, police, officials, volunteers and military personnel. Unfortunately, there was no possibility of saving lives - there were no survivors," he continued.
"Everything will be done to ensure we find, identify and recover the bodies of their victims and return them to their families."
16:41 - French investigators to reveal whether any findings from black box
The French authority responsible for safety investigations in aviation (Bureau d'Enquêtes et d'Analyses - BEA) is due to hold a press conference any minute where they are expect to reveal whether they have managed to glean any information from the black box.
The tweet below shows the scene of the press conference as journalists gather.
16:27 - Two Americans confirmed dead
The US State Department confirmed on Wednesday that two Americans died in the Germanwings plane disaster in the French Alps, reports AFP.
"At this time, we can confirm the deaths of two US citizens. We are in contact with family members and we extend our deepest condolences to the families and loved ones of the 150 people on board," said State Department spokeswoman Jen Psaki in a statement.
We can confirm deaths of 2 US citizens, are reviewing records to determine whether other US citizens might have been on board. #Germanwings
16:26 - Could the plane have suffered a cracked windscreen?
Rumours continue to swirl as to what exactly caused the crash. A thread on the Professional Pilots Rumour Network (PPRuNe) avitation forum saw the possibility of a cracked windscreen being discussed.
If this were so, it would have incapacitated the pilots, and would explain why they lost contact with the control towers so quickly.
Aviation safety expert Christophe Naudin told The Local on Wednesday that "until we hear from the investigators later on Wednesday, every theory that is being put forward is just conjecture".
15:54 - Second black box found - unconfirmed
Unconfirmed reports are coming in that the second black box has been found. AirLive.net tweeted that the box was "severely damaged" and that the memory chip was "dislodged and missing".
The first black box was found on Tuesday afternoon, and is already being examined in France.
The second black box collects data about the flight itself, whereas the first contained microphone recordings from within the pilots' cockpit.
15:53 - Video of Hollande and Merkel's arrival
The French president can be heard thanking emergency workers.
15:33 - Conflicting reports on number of Spanish victims
The Spanish government has just announced the number of Spanish victims in Tuesday’s Germanwings crash is 51, up from the 49 it announced earlier today. The figure was certified under the criteria of Spain’s security forces, the government said in the statement.
Germanwings executive Thomas Winkelmann had earlier estimated that there were 35 Spaniards on board the plane.
Certain discrepancies in nationality numbers could be due to passengers holding dual nationality.
15:30 - Lufthansa sends 'experienced' team to help emergency crew
A Lufthansa spokesman told The Local that its team in France was made up of experienced engineers with strong language skills and experience working in international environments.
The six-man “go team” will provide backup for government forensic investigators, and will be a point of contact for German officials on the scene of the crash.
The spokesman added that there were currently no planned changes to maintenance scheduled on Lufthansa's fleet of A320 aircraft.
"As long as there is no indication of the reason for the accident, for the time being we don't see any connection," he said.
"Any action will be taken when there's clear evidence."
15:25 - Spain sends psychology team to help in France
Spain is sending a delegation of psychologists to the village closest to the crash site to help with the grieving families. In all a team of eleven will go to France on the request of French authorities.
The three heads of state are in Vernet, the small town nearest to the crash scene, where they are meeting with families of victims.
15:12 - Spanish trolls investigated over air crash hate tweets
Spain has ordered a special police task force investigation in a bid to discover the identity of twitter trolls who used the Germanwings accident to send “anti-catalan” messages, reports The Local Spain.
"As well as expressing tremendous cruelty, they may constitute crimes which will have to be investigated and referred to the justice system," junior security minister Francisco Martinez told a news conference on Wednesday.
Tweets included: "A plane full of Catalans and Germans, crashing in France #winwinwin".
After spending 30 minutes or so meeting and shaking hands with the emergency team, President Hollande, Chancellor Merkel, and Spain's PM Rajoy have been driven away. It remains unclear as yet what their next move will be.
14:47 - Local town readies for 1,000 family members of victims
Meanwhile, in nearby Dignes, the town is prepared to house around 1,000 people who are related to the victims of the crash.
He was together with German chancellor Angela Merkel.
Spanish Prime Minister Mariano Rajoy is also expected on the scene, and the trio will meet with families and members of the rescue team.
14:11 - Second UK victim named
The UK's Foreign Office has named the second British victim as 28-year-old Paul Andrew Bramley.
It said in a statement that the man was from Hull, studied hospitality and hotel management, and was returning from a holiday with friends in Barcelona.
14:04 - Hollande, Merkel, and Rajoy on the way
French President Francois Hollande, German Chancellor Angela Merkel, and Spanish Prime Minister Mariano Rajoy are expected to touch down in the town of Seyne-les Alpes, where large crowds are already waiting.
He said the age of the 24-year-old plane is no concern, the possibility that pilots passed out from a lack of oxygen, and how it was "bizarre" that the crew didn't communicate about what indeed could have been a command breakdown.
"Although we can’t completely dismiss the theory of terrorism just yet, I am more convinced that the place suffered some kind of technical problem," he added.
13:18 - Germanwings revises nationality death figures
Budget airline Germanwings said Wednesday there were at least 72 Germans on its plane that crashed.
Company executive Thomas Winkelmann said there had been, according to the latest estimate, 35 Spanish victims, a figure far lower than the 49 cited by the Spanish government.
Winkelmann said that Germanwings was still working on establishing the nationalities of all the victims, a task complicated by the fact that some passengers had dual nationality.
The airline said it had established contact with the families of 123 victims and offered grief counselling to them and was working with the German foreign ministry to reach the last 27.
"Taking care of the victims' loved ones is our top priority," Winkelmann told reporters.
13:10 - First images of damaged black box emerge
Here is the first look at the black box voice recorder from the pilot's cockpit, broadcast by French news channel BFM TV. A French prosecutor said investigators hope to make initial findings from the evidence on the black box later on Wednesday.
(Photo: BFM TV screengrab)
13:00 - Families expected at site of crash
Preparations are being made to welcome the dozens of grieving family members that are en route to the crash site in the French Alps. A team of psychologists and trauma counsellors will be on hand to offer support to the families.
Language teachers from around the area have also been drafted in to help with interpretation problems. Accommodation for 900 people has been arranged in the local area.
12:30 - Spain raises number of dead to 49
The number of Spanish nationals killed in the plane crash has risen to 49. An initial figure of 45 was given on Tuesday but Madrid has now increased that number to 49. A full list of passengers and names has still not been released, leading many to question authorities. Germanwings insist they won't release it until all the families of passengers have been informed.
12:06 - Minute's silence observed in Germany and Spain
The Local Spain is on the scene at the Spanish Parliament, where a minute's silence has been held in memory of the 150 victims.
They include opera singers Oleg Bryjak and Maria Radner, pictured below, and three generations of the same family - a grandmother, her daughter and grandaughter from Sant Cugat del Vallès in Catalonia.
As well as the 67 Germans and 45 Spaniards, there are reportedly victims from countries including Turkey, Argentina, Israel, Denmark, the Netherlands, Australia, Mexico, Belgium, Kazakhstan, and the UK.
11:32 - German headmaster mourns 16 dead students
The headmaster of the Joseph-König-Gymnasium (secondary school) in Germany, which lost 16 pupils and two teachers in the crash, has held a press conference, reports The Local Germany.
"In our school, nothing is as it was before," he said.
"A week ago on Tuesday, we sent 16 happy young people with two happy young colleagues on an exchange with a school we've been linked to for six years."
Here is some more footage from the site, courtesy of the Guardian newspaper, with comments from Interior Minister Bernard Cazeneuve. He confirms that there is very little hope of finding survivors.
11:20 - Bad weather plagues day two of search
More than 300 policemen and 380 firefighters have been mobilised for the grisly task of searching the site, but the weather is bad and the access is worse.
"Ground access is horrible.... It's a very high mountainous area, very steep and it's terrible to get there except from the air during winter," local resident Francoise Pie told the AFP news agency.
French police set up road blocks near the crash site, ordering all non-official vehicles to turn around.
Just beyond lay a steep and broken landscape littered with the shattered pieces of what was flight 4U9525.
"It's a zone that is very difficult to access, very slippery. There was rain and snow overnight. So we need to secure the zone before the investigators begin their work," a spokesman for the French interior ministry, Pierre-Henry Brandet, told reporters.
"We are not in a race against time," he said. "We need to move forward methodically."
11:04 - Three Britons believed to have been on flight
A British man aboard the Germanwings flights has been named as Martyn Matthews, a 50-year-old father of two from Wolverhampton, reports UK paper the Telegraph.
He was on business in Barcelona, the paper added.
He leaves a wife, Sharon, 48, and children Jade, 20, and Nathan, 23, it said.
Foreign Secretary Philip Hammond has said that at least three Britons are believed to have been on board.
11:02 - Examination of black box set to commence
The examination of the damaged black box, which records conversations and noises in the cockpit, would begin "in the coming hours," pledged French Interior Minister Bernard Cazeneuve.
Transport Minister Alain Vidalies said that if voices have been recorded, the investigation would proceed "fairly quickly."
"After that, if we have to analyse the sounds, that's a job that will take several weeks, but it's a job that can offer us some explanations," Vidalies told French radio.
The Central Asian nation of Kazakhstan on Wednesday said at least three of its citizens died in the Germanwings airliner crash.
The death toll of 150 includes a reported 67 Germans, 45 Spaniards, as well as Australians, Columbians, Argentinians, a Dane, and potentially one British national.
Opera singers Oleg Bryjak, 54, and Maria Radner, 33, were also on board, flying to their home city of Duesseldorf. Radner was travelling with her husband and baby, one of two infants on board the plane.
Authorities have said they will publish official figures when they have notified the families of all the victims.
10:18 - German school children mourn
Pupils at the Joseph-Königs-Gymnasium (secondary school) in Germany gathered at the school on Wednesday despite classes being cancelled, reports our sister site in Germany.
“Yesterday we were many. Today we are alone,” a message written on a board outside the school read.
Sixteen pupils and two teachers were on the flight, returning from an exchange in Barcelona.
10:04 - Spanish parliament to hold minute's silence
Spain's parliament is planning to hold a minute's silence at noon to remember the victims of the Germanwings crash.
Mañana a las 12, en la escalinata de la Puerta de los Leones, minuto de silencio en memoria de las víctimas del accidente aéreo #Germanwings
09:58 - Merkel, Hollande, Rajoy due at site at 2pm
The French president will join German Chancellor Angela Merkel and Spain's PM Mariano Rajoy at the scene of the crash at 2pm. They are expected to meet with the families of some of the victims who are also being flown to the area, as well as police and air investigators whose job it is to search the site.
09:50 - One Danish national among the dead
Although a full passenger list has not been released yet, details are emerging of the nationalities of the 144 passengers on the plane.
Spanish Prime Minister Mariano Rajoy and Catalan regional president Artur Mas will travel together today to the crash site in the French Alps on a Spanish air force plane.
Meanwhile at 11am the crisis cabinet formed in response to the accident will hold a meeting led by deputy prime minister Soraya Saenz de Santamaria
09:29 - Investigators not focusing on terrorism theory
France's interior minister said investigators are looking into all possible causes of Tuesday's Germanwings crash in the French Alps, but he appeared to rule out the likelihood of a terrorist attack.
"The debris from the plane is spread over one and a half hectares, which is a significant area because the shock was significant but it shows that the plane did not appear to have exploded," Bernard Cazeneuve told French radio station RTL.
The theory of a terrorist attack is "not the theory we're focusing on," Cazeneuve said.
09:18 - 'A week to search the crash site'
One official says it will take a week to comb the wreckage of the crash site, given that debris is spread over a huge area.
This video gives an idea of the scale of the task facing investigators.
The horrific scene faced by the air investigators and rescue teams is becoming clear from some of the stories emerging from those who have visited the crash site.
"The biggest body parts we identified are not bigger than a briefcase," one investigator said.
More than 300 policemen and 380 firefighters have been mobilised for the grisly task of searching the site.
Lieutenant Colonel Jean-Marc Menichini said a squad of 30 mountain rescue police would resume attempts to reach the crash site by helicopter at dawn Wednesday, while a further 65 police were seeking access on foot.
Five investigators had spent the night camped at the site.
It would take "at least a week" to search the remote site, he said.
"Ground access is horrible.... It's a very high mountainous area, very steep and it's terrible to get there except from the air during winter," local resident Francoise Pie said.
08:58 - Swedish football team has lucky escape
As is often the case after plane crashes stories are emerging about those who narrowly avoided being on the doomed flight for one reason or another.
More on the damaged cockpit voice recorder, otherwise known as the black box from France's interior minister Bernard Cazeneuve. He confirms that it has been damaged but insists it is "usable". In other words he's hopeful that investigators can glean from it whatever they need to determine the cause of the crash.
08:50 - Specialist doctors sent to identify bodies
The harrowing task of identifying the bodies and remains of the 150 victims of the crash will fall to 10 specialist doctors who are being flown into the area on Wednesday.
08:44 - 'All hypotheses being looked at'
France's minister of the environment Ségoléne Royal has said all possible scenarios are being looked at to determine the cause of the crash but terrorism is not the main focus of the probe.
08:40 - Condolence books open near the site of crash
Condolence books are seen on March 24, 2015 in a sports hall in the southeastern French town of Seyne, near the site where a German Airbus A320 of the low-cost carrier Germanwings crashed, killing all 150 people on board.
08:05 - Rescue operations restart at crash site
Hundreds of military police and firefighters from the Alps have resumed the operation to salvage bodies and debris from Tuesday's crash.
With one official describing the plane and its contents as "pulverized" and that no piece of wreckage is bigger than a car, it looks set to be a long and harrowing task for emergency teams.
07:50 - Black box 'damaged'
The cockpit voice recorder recovered from the wreckage of the Germanwings Airbus that crashed killing all 150 aboard has been found damaged and has being taken to Paris for analysis, a source close to the inquiry said Wednesday.
"The black box that was found is the CVR," the source told AFP on condition of anonymity. The cockpit voice recorder (CVR) "was damaged. It has been transferred to Paris this morning."
A second so-called black box, in this case recording flight data, has yet to be found on the mountain in the French Alps where the Airbus A320 went down Tuesday.
07:45 - British nationals likely among dead
British nationals were likely on board the Germanwings plane that crashed in France on Tuesday, Britain's foreign minister said, in an aviation disaster that killed all 150 people on board.
"Based on the information available to us, it is sadly likely that there were some British nationals on board the flight," Foreign Secretary Philip Hammond said in a statement.
Hammond added that he did not want to speculate on how many British nationals were involved until passenger information checks were complete.
07:30 Argentines and Colombians also among victims
Two Argentines and two Colombians were on the Germanwings flight that crashed on Tuesday in the French Alps, killing all 150 on board, an Argentine diplomat said.
"We got in touch with the crisis center and they told us officially that there were two Argentines who boarded the flight," Santiago Martino, an official at the Argentine embassy in Paris, told Radio America.
Colombians Maria del Pilar Tejada and Luis Eduardo Medrano died in the crash near the southeastern French ski resort of Barcelonnette, the Colombian foreign ministry said, after French officials indicated there were no survivors from
the Airbus 320 jet wreckage.
"The news was confirmed directly to the family of the victims," a ministry statement said, without providing further biographical details of the deceased.
07:20 - Obama offers condolences
"It's heartbreaking because it apparently includes the loss of so many children, some of them infants," Obama said, adding that he had called Germany's Chancellor Angela Merkel.
"Our teams are in close contact, and we're working to confirm how many Americans may have been on board. Germany and Spain are among our strongest allies in the world."
Obama also called Spanish Prime Minister Mariano Rajoy, offering US assistance.
"The president conveyed his condolences and those of the American people to Spain and to the families of those lost on the flight," a White House statement said.