A 6.5 inch diameter hyper-hemispherical silicon dome was developed on IRAD for an infrared countermeasures aircraft
self-protection system. Having passed operational level environmental testing and many hours of flight performance, a
prototype dome was subjected to MIL test requirements in simulated crash safety testing at the manufacturer's facility.
Although the dome cracked during shock testing, it remained intact preserving aircraft integrity and actually passing
safety requirements. This paper describes design requirements, stress analyses of the dome and its mounting, and test
results including a forensic cause of failure study of the dome. The results add insight to the margins of safety normally
applied to the stress analyses of brittle optical materials and examine actual cause of failure in the prototype part.