Physical Process Failures and Dysfunctional Interactions

All the physical components worked exactly as intended, except perhaps for the IFF system. The fact that the Mode IV IFF gave an intermittent response has never been completely explained. Even after extensive equipment teardowns and reenactments with the same F-15s and different Black Hawks, no one has been able to explain why the F-15 IFF interrogator did not receive a Mode IV response [200]. The Accident Investigation Board report states The reason for the unsuccessful 

F-15 Lead On different radio frequencies i UH-60 (Black Hawk) helicopters  

F-15 Wing Using different IFF codes Not squawking TAQR IFF codes 

Using Have Quick radio mode Incompatible radios (HAVE QUICK) i Tuned to en route radio frequency 

Failures None except perhaps for the unexplained Mode IV problem Dysfunctional Interactions  

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