This SAE Aerospace Standard (AS) covers ULDs utilized in finding submerged aircraft. Such ULDs are installed within the aircraft in a manner that they are unlikely to become separated during crash conditions. The low frequency ULD should be attached to the airframe in accordance with the manufacturer’s recommendations in order to maximize the underwater detection range.
While Underwater Locating Devices (ULD) have been used for many years to indicate underwater location for aircraft crash survivable flight recorders, the detection range has been limited due to the defined performance characteristics, in particular with regard to the frequency of the transmitted pulse. A ULD operating at a lower frequency provides for an extended detection range which facilitates general position identification of a submerged aircraft. The low frequency ULD is intended to be mounted directly to the aircraft as a supplement to the existing ULDs which are attached directly to the crash protected recorders.