The start-up ended with an RN accident due to abnormal separation of one of the side blocks (block “D”), which hit the central part of the block (block “A”) in the fuel tank area, which led to its depressurization and, as a result, loss of stabilization of a space rocket. The reason for abnormal separation is the failure to open the lid of the nozzle cover of the oxidizer tank of the “D” block due to the deformation of the sensor of the separation contact sensor (bending to 6˚45 ') allowed when assembling the “bag” at the Baikonur cosmodrome. The cause of the RN accident is operational in nature and extends to the groundwork collected in the “package” of the Soyuz type PH