JAKARTA, Indonesia - The crash of a Russian-made passenger jet into the flanks of an Indonesian volcano has put a spotlight on the notoriously informal atmosphere aboard new aircraft during manufacturer demonstrations - known here as "joy flights."
These junkets for potential buyers commonly see passengers join or cancel at the last minute, wreaking havoc to manifest lists. Pilots eager to show off the versatility of their planes often make lightning-fast ascents and buzz famous landmarks.
With no sign yet of the black boxes, it is not clear what caused the Sukhoi Superjet 100 to smash into the side of Mount Salak on Wednesday, presumably killing all 45 people on board, and sending debris raining down a densely forested, jagged slope.
Search teams that scaled the steep slope found at least 12 bodies Friday near the wreckage.
An investigation by a joint team of Indonesian and Russian experts is expected to take at least a year.
There is nothing to suggest the pilot did anything wrong. But the disaster is a reminder of the concerns of air-safety specialists about demonstration flights. That's true not just in Indonesia - where several invitations from Boeing, Bombardier and other manufacturers land on the desks of airline executives and industry experts every year - but globally.
Tom Ballantyne, a Sydney-based aviation expert, has gone on many such trips.
"The purpose of these flights obviously is to show off the aircraft to potential customers," he said.
"If they are flying over a landmark, they might circle around it so the passengers can get a better look," he said. "They might fly a little lower or show the rate of climb of the aircraft."
That's not to say they don't follow the rules, he said, or push the planes beyond what they are capable.
"But there's definitely a bit of showing off."
With 240 million people and a rapidly growing middle class hungry for cheap air travel, manufacturers will continue to flock to Indonesia, as evidenced by a purchase late last year by the little-known airline Lion Air.
Its order of 230 planes from Boeing Co. was the manufacturer's biggest ever, and the carrier said it will need smaller aircraft as well. Lion isn't alone. Many other Indonesian carriers, some of which don't even have websites, also are trying to build up or modernize their fleets.
The ill-fated Superjet was carrying dozens of representatives from local airlines and journalists on what was supposed to be a 50-minute flight to the southern of Java island and back. Pictures posted on social networking sites like Facebook showed excited passengers, smiling and waving in front of the twin-engine jet before liftoff. Others sipped champagne handed out in the cabin by glamorous air hostesses wearing electric-blue pencil skirts.
Soon after takeoff from a Jakarta airfield, however, the Russian pilot and copilot asked air traffic control for permission to drop from 10,000 feet to 6,000 feet.
The plane disappeared from the radar immediately afterward - with new satellite imagery revealing heavy cloud cover and rain. It's not clear if that's why the crew asked to drop or if they got a response. Officials here say they didn't.
The pilots on demonstration flights are known to be experienced, often having spent years flying for major airlines.