  We analyse intensity variations, as measured by the Atmospheric Imaging
Assembly (AIA) in the 171 {\AA} passband, in two coronal loops embedded within
a single coronal magnetic arcade. We detect oscillations in the fundamental
mode with periods of roughly 2 minutes and decay times of 5 minutes. The
oscillations were initiated by interaction of the arcade with a large wavefront
issuing from a flare site. Further, the power spectra of the oscillations
evince signatures consistent with oblique propagation to the field lines and
for the existence of a 2-D waveguide instead of a 1-D one.
