CNN  — 

The Lion Air jet in Monday’s crash off Indonesia was a Boeing 737 MAX 8, one of the plane maker’s newest and most-advanced jets.

Indonesian authorities listed the plane’s registration number as PK-LQP. Soerjanto Tjahjono, head of the National Transport Safety Committee (NTSC), said the plane was delivered to Lion Air in August., a website that monitors air traffic, shows it was one of 11 Boeing 737 MAX 8s in the Lion Air fleet.

A Lion Air Boeing 737 MAX 8

The 737 MAX 8 is one of the latest versions of a jet that was introduced in 1967. More than 10,000 737s have been produced, making it the best-selling jetliner of all time.

CNN aviation analyst Peter Goelz called the loss of such a new aircraft “highly unusual.”

But because the Lion Air jet’s pilot and co-pilot were experienced – 6,000 and 5,000 flight hours respectively – and weather did not seem to be a factor, investigators would be focusing on the aircraft, said Goelz, a former chairman of the US National Transportation Safety Board.

The MAX versions of the 737s are touted for their LEAP jet engines which Boeing says “redefine the future of efficient and environmentally friendly air travel.” Boeing says the 737 MAX jets are 10% to 12% more efficient that their predecessors.

The LEAP engines are manufactured by CFM International, a joint venture between GE Aviation in the US and Safran Aircraft Engines of France.

In 2017, Boeing temporarily grounded all 737 MAX planes over concerns about a manufacturing quality issue inside its new engines.

Jamie Jewell, a spokesperson for CFM, said at the time that the company’s inspections found “some anomalies in the process” of manufacturing disks for the jet’s turbine. Jewell also stressed that no problems related to the part were seen in the more than 2,000 hours of test flights for the 737 Max.

The first Boeing 737 MAX  airliner, including fuel efficient LEAP engines, is pictured at the company's manufacturing plant, on December 8, 2015, in Renton, Washington.

Lion Air has been one of Boeing’s biggest customers for its 737s.

In 2011, the companies announced a $21.7 billion order for 230 of the single-aisle, twin-engine jets. Boeing at the time said it was the largest single order for commercial jets in Boeing history, both in terms of the number of planes and the dollar value.

The companies announced the deal at the East Asia Summit in Bali as then-US President Barack Obama looked on.

Visitors watch as a Boeing 737 Max lands after an air display during the Farnborough Airshow, south west of London, on July 16, 2018.

Since then, Lion Air has become the first airline to put the 737 MAX 8 into service in 2017, order and take delivery of the 737 MAX 9, and in April it ordered 50 of the 737 MAX 10, the largest of the line, in a $6.24 billion deal.

Besides the MAX series, Boeing builds three versions of the Next Generation 737, the 700, 800 and 900. Those planes are powered by different engines than the MAX.

To keep up with the orders, Boeing’s website says it’s making 52 planes in the 737 family every month at its factory in Renton, Washington, near Seattle.