  Within the context of the concordance model of cosmology we test the
consistency of the angular power spectrum data from WMAP and Planck looking for
possible systematics. The best fit concordance model to each observation is
used as a mean function along with a Crossing function with an orthogonal basis
to fit the data from the other observation searching for any possible
deviation. We report that allowing an overall amplitude shift in the observed
angular power spectra of the two observations, the best fit mean function from
Planck data is consistent with WMAP 9 year data but the best fit mean function
generated from WMAP-9 data is not consistent with Planck data at the $3\sigma$
level. This is an expected result when there is no clear systematic/tension
between two observations and one of them has a considerably higher precision.
We conclude that there is no clear tension between Planck and WMAP 9 year
angular power spectrum data from a statistical point of view (allowing the
overall amplitude shift). Our result highlights the fact that while the angular
power spectrum from cosmic microwave background observations is a function of
various cosmological parameters, comparing individual parameters might be
misleading in the presence of cosmographic degeneracies. Another main result of
our analysis is the importance of the overall amplitudes of the observed
spectra from Planck and WMAP observations. Fixing the amplitudes at their
reported values results in an unresolvable tension between the two observations
at more than $3\sigma$ level which can be a hint towards a serious systematic.
