PARIS -- Aviation experts, criminal investigators and soldiers began converging Friday on an isolated patch of restive Mali to search for clues that might explain why an Air Algerie jetliner fell from the sky in a storm and apparently disintegrated on impact.
French authorities said the catastrophe was probably the result of extreme bad weather, but they refused to exclude other possibilities, like terrorism, without a full investigation. All 118 people aboard the plane were killed.
The loss of flight 5017 wiped out whole families. Nearly half of the dead were French. The passenger list also included other Europeans, Canadians and Africans. The six crew members were Spanish.
One man pleaded with French officials not to hold back any information about the crash that killed his brother and other family members.
"Tell us. Especially give us an explanation," Amadou Ouedraogo asked on BFM-TV.
French authorities planned to meet Saturday with victims' families.
The MD-83 was flying from Ouagadougou, capital of Burkina Faso, to Algiers, Algeria, when it disappeared early Thursday just 50 minutes after takeoff -- the third crash of a passenger plane in the last week.
More than 200 French, Malian and Dutch troops from the United Nations force in Mali secured the site ahead of the arrival this weekend of aviation and criminal investigators.
France has opened a manslaughter investigation because of the 54 French victims.
One of plane's two black boxes was found Friday and sent to Gao, the northern Mali city where a contingent of French troops is based.
French Foreign Minister Laurent Fabius said victims' remains would be sent to Gao for identification before being returned home.
Difficult access to the area and instability could hinder the investigation.
Gao is in the heart of a still-restive desert and mountain area in northern Mali that fell under the control of Tuareg separatists, then al-Qaida linked Islamist extremists after a 2012 military coup.
French forces intervened in the west African country in January 2013 to rout Islamist extremists controlling the region. A French soldier was killed earlier this month in the Gao region.
The debris field to the south is in a concentrated area in the Gossi region near the border with Burkina Faso. The area is "in a zone of savannah and sand with very difficult access, especially in this rainy season," Fabius said at a presentation with the defense and transport ministers.
Traveling by road from the debris field to Gossi would take six hours, he said, stressing that the field investigation could take time.
Col. Patrick Tourron of the French Gendarmerie's victim-identification unit told BFM-TV that fingerprints, DNA and teeth would provide the primary clues to each victim's identity. Surviving family members were to be asked for victims' toothbrushes and the names of their dentists, he said.
Video of the wreckage site taken by a soldier from Burkina Faso, the nation first on the scene, showed unrecognizable debris scattered over a desolate area dotted with scrubby vegetation. There were bits of twisted metal but no identifiable parts such as the fuselage or tail, or victims' bodies. An aerial view shown later on French television revealed similar devastation.
Investigators from Mali, Burkina Faso, Algeria and Spain were joining the inquiry, the French foreign minister said.
It's too early to know "with absolute certitude" what caused the disaster, Fabius said, but he noted major storms in the region.
The pilot of the jet had advised controllers in Niger that he needed to change routes because of a storm, Burkina Faso Transport Minister Jean Bertin Ouedraogo said Thursday. Contact with the plane was then lost.
A French Reaper drone based in neighboring Niger spotted the wreckage after getting alerts from Burkina Faso and Malian soldiers, Defense Minister Jean-Yves Le Drian told reporters.
"There are hypotheses, notably weather-related, but we don't rule out anything because we want to know what happened," French President Francois Hollande said Friday after a crisis meeting.
Interior Minister Bernard Cazeneuve reiterated the same message: "We think the plane went down due to weather conditions." But, speaking on RTL radio, he added: "Terrorist groups are in the zone. ... We know these groups are hostile to Western interests."
The jet, owned by the Spanish airline Swiftair, had passed its annual air navigation certificate inspection in January without any problems, Spanish Deputy Prime Minister Soraya Saenz de Santamaria said Friday. The European Aviation Safety Agency also carried out a "ramp inspection" -- or unannounced spot check -- of the plane in June.
Santamaria said another ramp inspection was done in Marseille, France, on July 22 -- two days before the plane went down.
Ramp inspections "are limited to on-the-spot assessments and cannot substitute for proper regulatory oversight," the EASA website says. "Ramp inspections serve as pointers, but they cannot guarantee the airworthiness of a particular aircraft."
A Malaysia Airlines flight was shot down last week over war-torn eastern Ukraine. The U.S. has blamed it on separatists firing a surface-to-air missile. On Wednesday, a Taiwanese plane crashed during a storm, killing 48 people.