Indonesian special forces traversed the sheer slope of a volcano Monday after spotting what appeared to be the flight data recorder of a new Russian-made passenger jet that crashed during a demonstration flight for potential buyers.
It's not clear what caused the Sukhoi Superjet-100 to roar into Mount Salak at 800 kph (480 mph) last week. All 45 people aboard are presumed dead, and helicopters have been ferrying the remains to Jakarta, the capital, for identification.
Search teams say they spotted what is believed to be the combined voice-and-data recorder, also known as the "black box," peeking from the wreckage at the bottom of a 500-meter (1,500 -foot) ravine, said Tatang Kurniadi, who heads the National Transportation Safety Commission.
"We are really hoping they'll reach it sometime today," he said.
The Superjet _ Russia's first new model of passenger jet since the fall of the Soviet Union two decades ago _ was in Indonesia as part of a six-nation tour of Asia aimed at getting new customers.
Soon after take off from a Jakarta airport, the pilot was granted permission to drop from 3,000 meters to 1,800 meters (10,000 feet to 6,000 feet), said Mulya Abdi, general manager of Air Traffic Control in Jakarta.
The plane was 11 kilometers (7 miles) north of Mount Salak at the time, an area considered outside the danger zone around the notoriously perilous volcano, he said.
But it dropped off the radar immediately after, Abdi said, and then slammed into the jagged, mist-shrouded mountain.
A ground proximity warning system should have displayed positions and heights of the mountain and other obstructions on a screen in the cockpit, Indonesian aviation consultant Ruth Simatupang said, but it's possible that data about the terrain in that area had not been properly uploaded.
"Something's obviously wrong here," Simatupang said.
Patrick Smith, an American airline pilot and aviation author, said it's possible too that the equipment was not installed or for some reason was not turned on.
"But at this juncture, we have no idea what was going on up there," he said. "It's too early to try and pinpoint a cause."
There also was no sign after the disaster of the plane's emergency locator, which should have transmitted signals on various radio frequencies when it slammed into the cliff.
That slowed efforts to locate the wreckage.