How did World War I aircraft search for submarines over the sea?

During World War I, long-range flying boats operated from shore bases to conduct antisubmarine reconnaissance. These aircraft pioneered the use of methodical, mathematically developed search patterns to locate enemy submarines at sea.12

In addition to these fixed-wing aircraft, the British military utilized smaller, nonrigid airships for antisubmarine patrols, coastal reconnaissance, and convoy escort duties. These airships were highly effective in protecting coastal convoys from submarine attacks throughout the conflict.34