A classical, storm time Pc 5 event (T~160 s) was recorded by the satellite pair ISEE 1, 2 during an inbound, nearly equatorial pass in the dusk sector on August 21--22, 1978. Irregular and quasi-periodic pulsations composed of several harmonics (f~2--10¿10-3 Hz) were recorded from just inside the magnetopause at 11 RE to a distance of ~8 R, where the pulsations became nearly sinusoidal, and disappeared at ~7 RE just outside the plasmapause. Comparison of signals from the two spacecraft throughout the pass shows remarkable similarity of waveform at the second spacecraft following a few periods commensurate with the spacecraft separation time suggests that the two satellites were sampling slightly different phases of the same wave cycle.

The more distant, irregular pulsations were encountered by the two spacecraft with essentially no consistent delay between them, while the innermost, regular waves were always encountered first by the leading spacecraft. Cycle-by-cycle hodograms show nearly linear or highly elliptical polarization in the meridian plane everywhere on the inbound orbit, dominated by compressional waves. During the last few cycles the ellipses broadened and reversed phase at both satellites, just before the oscillations terminated, while the azimuthal amplitude went to zero at one satellite but not at the other. The Pc 5 pulsations occurred during an interval of strongly southward interplanetary magnetic field and substorm activity and were accompanied by Pc 1 waves at the spacecraft.