In the first reported total loss of one of Russia’s exceedingly rare fifth-generation Sukhoi Su-57 “stealth” fighters, one of the jets crashed approximately 68 miles from the Komsomolsk-on-Amur aircraft plant in Russia, where it was likely built. The pilot ejected from the aircraft safely and was recovered soon after the incident by Russian military MI-8 search and rescue helicopters.

“The Su-57 crashed during a test flight 111 kilometers from its home airfield,” Russia’s state-controlled United Aircraft Corporation (UAC) said as was quoted by the state-run RIA Novosti news agency.

It currently appears that the crashed jet belonged to Sukhoi and was undergoing testing just days before it and others were slated to be delivered to the Russian Ministry of Defense. Some reports have even indicated that the crashed Su-57 was the first production model of the aircraft. If true, that would mark a significant blow to the program.

According to Russia’s state-owned TASS news agency, the crash was caused by a control system failure, with one of two sources indicating that the failure pertained directly to the aircraft’s tail control surfaces. Russian officials said that an investigation is underway, and that the aforementioned conclusions are based on preliminary reports of what happened during the crash.

Russia has consistently claimed that it would receive its first batch of serialized production Su-57s prior to the end of this year — this was seen as a lofty goal for the long-troubled program.

Russia began the Su-57’s development in cooperation with India, though the Indian government backed out as it became clear that the aircraft was not going to meet their expectations in terms of stealth performance. Since then, Russia has maintained a token fleet of approximately 12 platforms, which have been used in the past to garner headlines by way of short, uneventful deployments to conflict zones like Syria.

Earlier this year, however, it was announced that Russia once again planned to put the fighter jet into production. This is perhaps because it may be courting new prospective buyers like Turkey, which was recently barred from purchasing the F-35 Joint Strike Fighter over its decision to procure advanced Russian air defense systems, rather than comparable systems provided by NATO partners.

The jet itself, which is widely considered to be not quite as “stealthy” as advertised, joins China’s J-20 on the list of advanced 5th generation fighters that claim to be able to stand toe to toe with the likes of America’s F-35 Joint Strike Fighter and the air superiority dynamo, the F-22 Raptor. The Chinese and Russian jets, however, exist in far too few numbers to offer their respective nations any real combat capability. To date, there are fewer than 20 operational J-20s, and far fewer Russian Su-57s.