An expert system for validating ionograms autoscaled by the University of Massachusetts-Lowell system Automatic Real Time Ionogram Scaler with True Height (ARTIST) is described. The expert system is implemented as a FORTRAN program QualScan. QualScan reads in the standard archiving output file that is created by ARTIST, which is an ASCII summary of the salient information about the scaled trace, and attempts to determine if the scaled trace is a valid representation of the actual ionogram. It provides an overall quality figure for the scaled trace, based mainly on its reasonableness, and defines error bars for the main F2 layer parameters and for the F2 plasma frequency profile. QualScan can be used on a single ionogram for real-time operations or on a batch of ionograms for qualifying data to be stored in ionospheric databases. QualScan typically "fails" one-third of ionograms from low-latitude and midlatitude sites.