On January 19, 1972, in situ measurements by instruments on Explorer 45, orbiting in the magnetosphere near the equatorial plane, and ISIS 2, in a circular polar orbit at 1400 km, simultaneously detected patches of enhanced ionization outside the main body of the plasmasphere. The magnetospheric plasma region extended between L values 3.4-4.8 and the ionospheric electron density enhancement extended between L values 3.6-4.4. The two plasma features were detected near 22 hours MLT. From the observations, including some made before and after the simultaneous measurements, we infer that the plasma density enhancement persisted for more than 5 hours and extended over at least 2 hours in magnetic local time near L=5. Our results provide experimental evidence that some detached magnetospheric plasma regions are signatures of a flux tube containing enhanced ionization throughout a volume extending from the topside ionosphere out to the equator.