Well, it is not exactly accurate to say that no aircraft crash has or will be attributed to terrorist.
For example, we know that the four aircraft that came down on 911 were terrorist attacks.
Since then, we know that in December 2001, American Airlines Flight 63 was attempted to be destroyed in flight by Richard Reid, the “shoe bomber”, who was associated with al-Qaeda.
We know that in 2004 Russian aircraft bombings Islamist terrorist attacks on two domestic Russian passenger aircraft flying from Moscow,Volga-AviaExpress Flight 1353 and Siberia Airlines Flight 1047. The bombs were triggered by two female Chechen suicide bombers and both plains crashed with a toal loss of life of 89 persons. Shamil Salmanovich Basayev militant leader of the Chechen terrorist movement claimed credit.
We know that on December 25, 2009, Northwest Airlines Flight 253 was attempted to be destroyed by Umar Farouk Abdulmutallab who tried to detonate explosives sewed into his underwear and al-Qaeda in the Arabian Peninsula claimed responsibility for the attempted bombing.
Had Richard Reid succeeded in bringing down AA 63, I’m not so sure we’d know his name today.