Complex sentence: However, ATC suspended training at its Nellis-based fighter weapons school in late 1956 because of the almost total failure of the F-86 Sabre aircraft used at Nellis.
Split into simpler sentences: However, ATC suspended training at its Nellis-based fighter weapons school in late 1956. The reason for the suspension was because of the almost total failure of the F-86 Sabre aircraft used at Nellis.