The terrorists in Hijack are revealed to be using blanks instead of real bullets in episode 3 "Draw A Blank". As the episode title implies, the five supposedly armed hijackers are wielding real guns on Kingdom Flight 29 but specifically loaded them only with blank bullets. While blanks can still be dangerous and even lethal in some instances, the lack of actual bullets in the terrorists' weapons exposes a major vulnerability in their hijacking plans. Surprisingly, the terrorists have hardly used violence to take control of the plane thus far, but that intention might not sustain throughout the four remaining episodes of Hijack.

https://screenrant.com/hijack-terrorists-blank-bullets-explained/