JAKARTA — A Russian Sukhoi Superjet 100 with about 50 people on board went missing in a mountainous area south of the Indonesian capital Jakarta during a demonstration flight Wednesday, officials said.
"The plane disappeared from the radar around the Bogor area. We are still looking for it and we are uncertain whether it crashed," said Gagah Prakoso, spokesman for the national search and rescue agency.
Around 200 police, military and rescue workers were headed in vehicles and on foot towards Salak mountain where the plane went missing, he said.
"We suspect the plane crashed, but we're not yet certain," rescue chief Marsdya Daryatmo told reporters several hours after the disappearance.
"We tried to send two helicopters to search for the plane... but because of bad weather and strong winds they had to return. We will send them out again tomorrow," he said.
The Superjet 100 is a new passenger aircraft built by legendary Russian planemaker Sukhoi in an attempt to lift the country's civil aviation industry from a post-Soviet crisis.
The Superjet only made its first commercial flight last year and if a major accident is confirmed it would be the first disaster to involve the aircraft.
The plane took off at 2:00 pm (0700 GMT) from east Jakarta's Halim Perdanakusuma airport, which is used for some commercial and military flights.
"At 2:50 pm it dropped from 10,000 feet (3,048 metres) to 6,000 feet," the rescue agency said in a text message to AFP.
The Salak mountain, where the plane disappeared, is more than 7,200 feet (2,200 metres) high.
There were scenes of grief at the airport, with relatives of some passengers weeping uncontrollably as they waited on tenterhooks for more information about the missing plane.
Reports of the exact number on board varied slightly, with Prakoso saying it was carrying 46 people and Trimarga Rekatama, the company responsible for inviting the passengers saying 50 were on board.
Russia's RIA Novosti news agency reported 36 non-Russians on board and eight Russians, four of them crew and the others Sukhoi company representatives. It named the captain as Alexander Yablontsev, 57, a veteran pilot.
Herry Bakti, head of the aviation division of Indonesia's transport ministry, said Superjet was on the second of two demonstration flights, and those on board were invited guests.
"It was just going to briefly circle the area and land back at Halim airport," he said.
A list of 36 passenger names posted at Halim airport showed that most of them were Indonesian airline and aviation officials, plus five journalists and a representative of French aircraft engine maker SNECMA with a Vietnamese name.
The French embassy in Jakarta confirmed there was one Frenchman aboard.
The Superjet is crucial to Russia's hopes of becoming a major player in the modern aviation market and improving its image in the industry, which has been scarred by frequent crashes of ageing Soviet-era jets.
The project is a joint venture between Sukhoi and Italy's Alenia Aeronautica, part of aerospace and defence giant Finmeccanica.
A mid-range airliner, the Superjet 100 is designed to carry up to 98 passengers and is a direct rival of similar aircraft produced by Brazil's Embraer and Canada's Bombardier.
So far it is being flown by two airlines, Russia's Aeroflot and Armenia's Armavia, although orders have been confirmed with several more. Its first commercial flight was operated by Armavia in April 2011 and Aeroflot followed later that year.
Indonesia's official Antara news agency said that domestic carrier Kartika Airlines and regional Sky Aviation had both placed orders for the plane.
The demonstration flight in Indonesia was part of an Asian roadshow to promote the aircraft that started May 3. It earlier took in Kazakhstan and Pakistan, and was due to go on to Laos and Vietnam.
A source at the Russian Ministry of Industry and Commerce told the Interfax news agency: "Preparations before the flight were carried out in full, and technically the plane was in perfect condition."
But the Superjet has experienced some troubles while being flown by Russian flag carrier Aeroflot, which has been under heavy pressure from the government to add more Russian planes to its fleet.
Aeroflot's first Superjet spent several weeks grounded upon delivery because of an air conditioning problem, and in March, a plane had to cut short a scheduled flight after it encountered problems with its undercarriage.
The sprawling Indonesian archipelago relies heavily on air transport but has a poor aviation safety record.