  The inclination of galaxies induces both reddening and extinction to their
observed spectral energy distribution, which in turn impact the derived
properties of the galaxies. Here we report a significant dependence of the
error in photometric redshift (photo-z) on the inclination of disk galaxies
from the Sloan Digital Sky Survey. The bias in the photo-z based on the
template-fitting approach increases from -0.015 in face-on to 0.021 in edge-on
galaxies. A Principal Component Analysis on the full sample of photometry
reveals the inclination of the galaxies to be represented by the 2nd mode. The
corresponding eigenspectrum resembles an extinction curve. The isolation of the
inclination effect in a low-order mode demonstrates the significant reddening
induced on the observed colors, leading to the over-estimated photo-z in
galaxies of high inclinations. We present approaches to correct the photo-z and
the other properties of the disk galaxies against the inclination effect.
