OVERVIEW: The LY-402 is a fuel-air explosive (thermobaric) bomb developed by China for wide-area neutralization of infantry, light vehicles, and infrastructure in enclosed or open environments. It contains a high-energy thermobaric warhead.

DETAIL: The LY-402 FAEB (Fuel-Air Explosive Bomb), also known under the industrial designation CS/BBF1, is part of China’s family of thermobaric weapons designed to create intense overpressure and prolonged heat effects. Unlike traditional explosives, the LY-402 releases a fuel cloud upon deployment which is then ignited to generate a powerful pressure wave and sustained thermal pulse. This makes it particularly effective in destroying bunkers, caves, and entrenched infantry positions. Its design resembles early Soviet and Western FAEBs, but it has been adapted for compatibility with Chinese attack aircraft and bombing doctrine. The weapon is believed to use a two-stage dispersal and ignition system for optimal atmospheric mixing and blast effect.

This munition is typically carried by tactical aircraft such as the JH-7A or Q-5, and is intended to clear fortified areas or kill unarmored concentrations before a ground advance. It is also applicable in anti-runway or anti-structure roles due to its high pressure yield and thermal damage. The bomb is unguided but may be delivered with high precision using modern fire-control systems.

Operational use would involve low- to medium-altitude delivery over target zones such as bunkers, forested areas, or compound clusters. The thermobaric nature of the warhead is optimized for enclosed spaces, making it well-suited for urban warfare or mountain region clearances.

NOTE:
IOC: ~2000s
Operators: China (People’s Liberation Army Air Force)
Platform: Xian JH-7A, Nanchang Q-5, possibly Su-30MKK (PLAAF variant)
Conflicts: Not publicly confirmed in combat use

SOURCE:
Norinco Catalogues ; Chinese Military Aviation (Scramble) ; Jane’s Weapons: Air-Launched ; SIPRI Arms Transfers Database ; Federation of American Scientists (FAS)
https://www.fas.org/man/dod-101/sys/dumb/fae.htm