The echolocation transmission beam pattern of a false killer whale (Pseudorcacrassidens) was measured in the vertical and horizontal planes. A vertical array of seven broadband miniature hydrophones was used to measure the beam pattern in the vertical plane and a horizontal array of the same hydrophones was used in the horizontal plane. The measurements were performed in the open waters of Kaneohe Bay, Oahu, Hawaii, while the whale performed a target discrimination task. Four types of signals, characterized by their frequency spectra, were measured. Type‐1 signals had a single low‐frequency peak at 40±9 kHz and a low‐amplitude shoulder at high frequencies. Type‐2 signals had a bimodal frequency characteristic with a primary peak at 46±7 kHz and a secondary peak at 88±13 kHz. Type‐3 signals were also bimodal but with a primary peak at 100±7 kHz and a secondary peak at 49±9 kHz. Type‐4 signals had a single high‐frequency peak at 104±7 kHz. The center frequency of the signals were found to be linearly correlated to the peak‐to‐peak source level, increasing with increasing source level. The major axis of the vertical beam was directed slightly downward between 0 and −5°, in contrast to the +5 to 10° for Tursiops and Delphinapterus. The beam in the horizontal plane was directed forward between 0° and −5°. In both planes, the type‐1 signals had the broadest beam pattern, followed by the type‐2 and type‐3 signals, with the narrowest beam pattern being exhibited by the type‐4 signals. The beam pattern in the horizontal plane was much narrower than the beam pattern in the vertical plane.

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