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. ARINC Standard 677 also provides installation guidance for Low Frequency ULDs. Purpose This Aerospace Standard specifies minimum performance standards for low frequency acoustic ULDs which are primarily intended for use with both fixed and rotary wing civil aircraft.