11 February 1949; August–December 1949 / T042
Project Grudge replaces Sign
Wright-Patterson Air Force Base, Ohio
Witness account
Project Grudge replaced Sign and issued an August 1949 assessment of earlier reports. The approach emphasized conventional explanations, mistaken observations and insufficient information. A December announcement ended its special-project status, although UFO reporting did not disappear and organized work was later revived.
Public record
The Grudge report and administrative record survive; this is distinct from the unlocated Estimate associated with Sign.