|Proton M/Briz M|
|Launch vehicle||Proton M/Briz M|
|Launch site||Baikonur, Kazakhstan|
|Date/Time||2007-09-05 22:43 UTC|
|Description||First/second stage separation failure|
|Desired orbit||5,032 km x 35,768 km x 21.4 degrees geostationary transfer orbit|
The rocket experienced a second-stage separation failure and engine shutdown 139 seconds into flight. It crashed down in the central Kazakh steppe.
The Russian State Commission investigating the unsuccessful launch determined that a damaged pyro firing cable on the interstage truss prevented the activation of the pyro bolts that were to have separated the first and second stages of the rocket. This led to an emergency shutdown of the engine and the subsequent crash.