Plasma density structures are frequently encountered in the nighttime low-latitude ionosphere by probes on the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. Of particular interest to us here are plasma density enhancements, which are typically observed ±15° away from the magnetic equator. The low inclination of the C/NOFS satellite offers an unprecedented opportunity to examine these structures and their associated electric fields and plasma velocities, including their field-aligned components, along an east-west trajectory. Among other observations, the data reveal a clear asymmetry in the velocity structure within and around these density enhancements. Previous data have shown that the peak perturbation in drift velocity associated with a density enhancement occurs simultaneously both perpendicular and parallel to the magnetic field, while the results in this paper show that the peak perturbation in parallel flow typically occurs 25–100 km to the east of the peak perpendicular flow. The absence of such a longitudinal offset in previous observations suggests that multiple physical mechanisms may be responsible for creating plasma density enhancements as observed by satellite-borne instrumentation.