In Brazil's president, Luiz Inácio Lula da Silva, expressed his determination to find the plane.
"A country that could find oil in 3,700 meters deep in the ocean is going to be able to find a plane 1,200 meters deep," he said in a statement.
Passenger Arthur Coakley's wife keeps trying his cell phone -- also determined to get an answer.
"I haven't tried it today, but yesterday it was ringing," said Patricia Coakley. "So maybe they're not at the bottom of the sea."
The reasons behind the crash remain unclear, with many speculating that it could have been a result of thunderstorms and lightning or a combination of both. The four-year-old Airbus jet did have sophisticated radar that should have helped the pilots try to skirt any violent weather.
Arslanian said that to the best of his knowledge, the pilot at the controls told Brazilian air control that he was experiencing turbulence about 30 minutes before the plane's disappearance. He said it was unclear whether the chief pilot was in the cockpit when the plane went down, since pilots usually take turns at the controls during long flights.
He stressed that the investigation was only in its early stages, and he could not confirm how the plane went down.
"We don't even know the exact time of the accident," he said, adding that "our objective today is to publish the first report by the end of June."
A series of automatic messages was sent by the plane's system just before it vanished, reporting lost cabin pressure and electrical failure. Arslanian said the messages were received in a time frame of three minutes. Investigators were working to interpret these messages, he added, saying that he did not want to go into details at such an early stage of the probe.
ABC News has also confirmed that two commercial planes flew virtually the same route as that taken by the Air France jet before and after the missing flight. According to a Lufthansa airlines statement, its flight in the area "operated normally without any irregularities reported by the crew."
French Transport Minister Jean-Louis Borloo said Tuesday he did not believe bad weather alone could have brought the plane down. He also brushed off the idea that terrorism or a hijacking could be involved.
Nance agreed that it would be almost unheard of for a plane to be downed by lightning alone but added, "You never say never."
Nance also said Tuesday it's unlikely that turbulence could break up a plane: "In most circumstances, absolutely not," he said. "The aircraft can take anything the atmosphere can throw at it, except for tornadoes."
In very rare cases, Nance said, a plane could be trying to recover from severe turbulence and then hit more, causing too much stress for the plane.
AccuWeather's Ken Reeves said towering thunderstorms are common over that area of the Atlantic. He said planes typically fly at about 35,000 to 37,000 feet, and storms in the tropics can be as high as 50,000 feet.
"In that part of the tropics, with as high as the thunderstorms are, it can be difficult having to go hundreds and hundreds of miles out of your way in order to just get to the point you're trying to get to," Reeves said.