"The rise in worldwide terrorism has required measures be taken to harden aircraft against catastrophic in-flight failure due to concealed explosives. Commercial aviation can be protected from the threat of explosives by : 1. preventing explosives from reaching the aircraft 2. mitigating the effects of an explosive protecting the aircraft from an onboard explosion. The risk that a small quantity of an explosive, below the threshold of the detection instruments, could get undetected should be considered, and the introduction of contermeasures to reduce the effects of on-board explosions should be considered. This is the idea behind FLY-BAG. Hardened containers (HULD) have been developed for the latter scope, but have some disadvantages which prevent their wider utilisation: they are heavier and more costly than standard luggage containers and only applicable to wide-body aircrafts. The issue of containing explosions aboard narrow-body aircraft must be resolved. Our concept is based on the development of flexible textile-based luggage containers able to resist a small to medium explosion by controlled expansion and containment of the shock waves whilst, at the same time, preventing hard luggage fragment projectiles (shrapnel) from striking the main structure of the aircraft at high speed. A multi-layered ""soft-sandwich"" structure is required to absorb the large dynamic loads of the explosion and the large deformation related to the gas expansion. Our idea is to use a multi-axial textile structures made of ballistic yarns as an internal high strength layer, coupled with an external ""foldable"" layer which could deform in a controlled way during the explosion, in a way similar to air-bags in cars. Composite elements like thin strips or thin sheets contribute with reinforcement and containment functions. A core layer will be considered as well e standoff distance between an explosive device and the aircraft skin panels to reduce shockholing and blast forces."