Report: Upside-Down Sensors Toppled Russian Rocket The "angular velocity sensors" were a critical part of the circuitry that was supposed to keep the rocket upright during launch. A young technician got the installation wrong, according to the site Russian Space Web.
July 10, 2013 - NPR
Upside-Down Sensors Caused Proton-M Rocket Crash Michi writes "According to Anatoly Zak, the crash of the Russion Proton rocket on 1 July was apparently caused by several angular velocity sensors having been installed upside down. From the source: 'Each of those sensors had an arrow that was supposed to point toward the top of the vehicle, however multiple sensors on the failed rocket were pointing downward instead.' It seems amazing that ...
July 10, 2013 - Slashdot