The aircraft that became EP-CPG had already lived several lives before that July morning. Built in 1987, it entered service as YA-TAR with Bakhtar Afghan Airlines, flying in a country that was then in the midst of the Soviet-Afghan War. In 1988, it was transferred to Ariana Afghan Airlines. A decade later, it was sold to Caspian Airlines in March 1998 and re-registered in Iran as EP-CPG in March 1999. The Tu-154, a Soviet-designed trijet, was a workhorse of airlines across the Eastern Bloc and its successor states -- reliable but aging, with a safety record that had drawn increasing scrutiny by the 2000s. The aircraft had been inspected in June 2009 at Mineralnye Vody Airport in southern Russia and cleared to fly until 2010. One month later, it was gone.

The crash investigation pieced together a cascade of mechanical failures that left the crew with no chance. It began with fatigue failure in a rotor disc inside the left engine -- engine number one. The disc did not simply crack; it disintegrated, sending fragments tearing through the aircraft's systems. Those fragments severed two of the three hydraulic control systems that allowed the pilots to steer the plane. They also ruptured fuel lines feeding the center engine -- engine number two. Fuel spraying from the broken lines ignited, creating a fire that burned through the components controlling the elevators and rudder. Without hydraulics, without control surfaces, the pilots were left fighting an aircraft that could no longer respond to their inputs. The tail had caught fire. The crew circled, searching desperately for a place to land, but the situation was already beyond recovery.

The aircraft struck a field near the village of Jannatabad outside Qazvin at 11:33 local time. The impact carved a crater up to 10 meters deep. Three hours later, fires still burned across an area of 200 square meters. All 168 people aboard perished -- families traveling between Tehran and Yerevan, among them at least 40 Armenian nationals and two Canadian citizens. The crash was the second-deadliest aviation disaster worldwide in 2009, behind only Air France Flight 447, which had plunged into the Atlantic Ocean just six weeks earlier. In the grim history of Iranian aviation, Flight 7908 ranked as one of the country's worst disasters, following Iran Air Flight 655, shot down by a US Navy cruiser in 1988, and a 2003 military transport crash.

The black boxes were recovered, though they had been damaged in the crash and fire. The investigation, conducted with assistance from Russia's Interstate Aviation Committee, confirmed the mechanical chain of events: rotor disc fatigue, engine disintegration, hydraulic failure, fuel fire, loss of control. There was no pilot error, no weather factor, no external threat. The aircraft had simply come apart from the inside. The Tu-154 had been one of the most widely produced Soviet-era airliners, with over a thousand built. But its three-engine design, while providing redundancy in theory, could not survive a catastrophic failure that sent shrapnel into adjacent systems. Flight 7908 became part of a broader reckoning with aging Soviet-era fleets in countries where sanctions, economics, or both made replacement aircraft difficult to obtain. For 168 people who boarded a routine morning flight from Tehran to Yerevan, the consequences of that calculation proved fatal.