scope:

Description of Driving Event:

The following mishap occurred during preparation of three mighty mouse rockets (2.75" FFAR) at the NASA Atmospheric Sciences Field Laboratory: The last step before arming the FFAR motors was to replace the activation plug on the payload. With the rocket in position in the launcher tube, the plug used during launcher loading was removed through an access hole in the side of the tube and another plug, attached by a lanyard to a pneumatic withdrawal cylinder, was inserted in the payload. While the worker was performing this lanyard insertion step, the rocket motor ignited and launched. Investigation of the mishap revealed the high probability of a sneak circuit causing the inadvertent firing of the rocket.