The HIgh Bandwidth Auroral Rocket (HIBAR), launched into active pre-midnight aurora, encountered two bursts of 2--10 mV/m upper hybrid waves just below fuh = 2fce at approximately 377 and 390 km altitude. These waves occur in association with a density shoulder and enhancement, respectively. The waves show several bands of frequency structure with 4--8 kHz spacings and, within these, bands of frequency sub structure with 1--2 kHz spacings. At the time of the waves, the measured electron distribution indicates wave instability for frequencies 1--1.2% percent below the electron cyclotron harmonic. These results agree qualitatively with theoretical work predicting banded structure associated with upper hybrid waves trapped in density enhancements.