A shock sensor (20) having some structural similarities to a reed switch, particularly in the use of a glass capsule (22) which hermetically seals the components of the shock sensor. The shock sensor employs a sensing mass (31) mounted on a metallic planar spring (32). Under the influence of a crash-induced acceleration, the sensing mass is driven against a fixed contact to close an electrical circuit. To extend the closure duration and increase the reliability, the contact surface (40) which is formed on the sensing mass is oriented at an angle of 60 degrees out of the plane containing the spring.