Modern commercial aircraft cockpits are designed to be bullet-resistant, rather than strictly "bulletproof" in the military sense. Following the 9/11 attacks, global aviation authorities (like the FAA and EASA) mandated that all commercial planes be fitted with reinforced cockpit doors. These doors are constructed from advanced materials like Kevlar and reinforced steel to prevent forced entry and are tested to withstand small-arms fire and fragmentation. While they provide an incredibly high level of protection, the term "bulletproof" is avoided by engineers because no door is entirely impervious to sustained, heavy-caliber ballistic attacks or explosives. In 2026, security protocols also focus on the "Secondary Barrier"—a secondary gate that is locked whenever a pilot needs to exit for a break, ensuring there is never a direct, unprotected path into the flight deck.