The magnetic field data acquired by the TRIAD satellite sometimes show variations with periods longer than 10 min and with amplitudes of a few thousand nano Teslas due to attitude oscillations. From a study of 150 passes, the principal oscillations of TRIAD have been identified as the well-known librations of gravity-stabilized satellite. The libration periods are approximately To/2 and To/(3)1/2, where To is the orbit period of about 100 min. The amplitude and phase of these librations appear to change over periods of a few days, and sometimes they vanish altogether. By use of data acquired over several consecutive TRIAD orbits, these attitude variations can be numerically evaluated and removed, leaving the disturbances associated with Birkeland currents. The establishment of a 'base line' for the TRIAD observations by using this technique has permitted, for the first time, a preliminary evaluation of the 'current-free' magnetic field disturbance due to large-scale Birkeland currents. Data acquired from three consecutive TRIAD passes (spanning more than 3 hours) show nearly the same magnetic disturbance profile, which extends as far as 10 degrees in latitude from a single (net) region 1 Birkeland current sheet. These observations confirm the permanent and global nature of large-scale Birkeland currents.