A Russian Aerospace Forces Su‑57 fifth generation fighter has crashed during a training flight near Zvenigorod in the Moscow region.

The pilot ejected successfully and survived without injuries. Images from the crash site show wreckage scattered across a wooded area, confirming the destruction of the aircraft.

Russian sources have reported that the fighter was mistakenly engaged by the BARS‑Moscow Air Defence Unit, a volunteer territorial formation created to protect the capital from frequent Ukrainian drone attacks.

This marks the first recorded friendly fire incident resulting in the destruction of a stealth fighter. It follows a prior case in March when Iranian air defences successfully targeted a U.S. Air Force F‑35A. 

Russian authorities have announced the opening of a criminal investigation into potential violations of flight regulations or failures in pre‑flight preparation, which is standard procedure after the loss of high‑value military assets.

Air defences around major Russian cities have been under severe strain due to persistent Ukrainian ballistic missile, cruise missile, and drone attacks. This pressure has increased the risk of misidentification, particularly during heightened alert periods.

The complexity of layered defence networks designed to counter low‑flying unmanned aircraft has made distinguishing friendly aircraft more difficult. Similar incidents have occurred elsewhere, such as the mistaken shootdown of three U.S. Air Force F‑15E fighters by Kuwaiti aircraft in March, which were misidentified as Iranian jets.

The Su‑57 fleet has expanded significantly over the past four years, growing several times larger than its pre‑war size. Production has accelerated despite the fighter’s high cost and complexity, with deliveries occurring at higher rates than any other Russian fighter type.

The aircraft have been increasingly active in combat operations, with Ukrainian sources reporting intensified Su‑57 strikes in May and September 2024, and further reports in August 2025 indicating operations involving whole formations.

Despite this growth, the fleet remains limited, with only 48–65 aircraft estimated to be in service. The loss of a single fighter is therefore a notable blow. Russia plans to expand the fleet to 76 aircraft by the end of 2026, enough to equip three full regiments plus four additional fighters. Production continues at the Komsomolsk‑on‑Amur Aircraft Plant, where efforts are underway to meet these targets.

The Su‑57 has played a significant role in the Ukrainian theatre, conducting air defence suppression, air‑to‑air combat, and precision strike missions in heavily defended airspace. It has carried missiles both internally and externally, adapting to diverse mission requirements.

However, the friendly fire incident highlights the urgent need for improved coordination between aircraft and ground‑based systems, particularly as Ukrainian strikes penetrate deeper into Russian territory.

Although the Su‑57 has undergone more intensive combat testing than any other fighter of its generation, the program remains nearly a decade behind schedule. The aircraft is entering service in meaningful numbers at a time when China is nearing deployment of its first sixth generation fighters. 

The United States, while behind China in development, remains well ahead of Russia. Consequently, the Russian Aerospace Forces are expected to rely on the Su‑57 as their most advanced fighter type well into the sixth generation era.

ANI