We present the first rocket measurements of equatorial spread F irregularities at altitudes significantly above 600 km, in what is believed to be the inertially dominated regime of spread F. On October 14, 1994, at 1955 LT (2255 UT) a Black Brant X rocket instrumented to measure plasma density and electric fields was launched from Alca⁁ntara, Brazil (2¿18.75' S, 44¿22.3' W, dip angle 1.5¿ at 300 km altitude), into active topside spread F plumes. On upleg the payload remained continuously in these plumes up to an altitude of 822 km. Power spectra of electron density fluctuations show characteristic dual-power law behavior with spectral indices of -1.7 at frequencies below 60 Hz and -5 at frequencies above 60 Hz. Shocklike coherent structures characterized the density waveforms. The electric field fluctuations had spectral indices ranging from -3 to -4. We observe no evidence of altitude variation in the spectral indices or in the density fluctuation waveforms. Over the entire altitude range of the observations, 350--822 km, the data remain in agreement with previous measurements of collisional spread F below 600 km. ¿ 1998 American Geophysical Union