A story from the Associated Press earlier this month (courtesy of the San Francisco Chronicle) reinforces the importance of paying attention to what you are doing.

Lockheed Martin dropped a NOAA satellite (NOAA-N) on its side during a routine operation to move it from a vertical to horizontal position. The apparent problem: the bolts holding the satellite to the jig had been removed a day beforehand and nobody checked to see if the bird was secure before turning it.