In 1962 the Army began developing an improved version of the APH-5. Combat experience in Vietnam led the Army to develop a flight helmet with better ballistic protection. Introduced in 1965, the new Anti-fragmentation Flight Helmet, or AFH-1, was fielded. Whereas the APH-5 was standard issue throughout the Army, the AFH-1 was issued only to aircrew members in Vietnam. Due to production problems, the AFH-1 was available in limited numbers only. As a result, the APH-5 continued to see widespread service in Vietnam. Although providing better ballistic protection, the AFH-1 suffered from a major drawback, weight. Weighing roughly a pound and half more than the APH-5, it was unpopular with aircrew members and was often shunned in favor of the lighter, those less protective, APH-5.
Despite the weight advantage the APH-5 had over the AFH-1, it too suffered from deficiencies that would eventually lead to it being replaced. Aircrew members complained that the APH-5 was too hot, too tight, and, most importantly, too heavy. The Army determined the helmet provided inadequate hearing protection.
Source: Air Warrior: Evolution of the Flight Helmet (by Kevin Sullivan, 2011-12-13)
Stock Number Reference:
Helmet, Flying, Type AFH-1