AIRS and CrIS are in very similar 1:30 PM ascending node orbits, with 12 km diameter footprints at nadir. Data from both instruments have have been available for the past 5 years. The level to which AIRS and CrIS observations agree for large area averages is a metric of how well data from different, but nominally equivalent, instruments can be concatenated to create the long time series necessary to reliably characterize climate change. We limit our analysis to 900 cm-1 atmospheric window channels. For random nadir sampled tropical zone data AIRS and CrIS agree within 100 mK, if the nine CrIS detector elements are averaged. Under tropical mean condition the CrIS elements disagree from each other by 0.5K. Under extreme condition the measurements of the nine CrIS elements are between 2K colder to 3 K warmer than AIRS. It is at present unclear why the nine CRIS detector elements disagree with each other by much more than their mean disagrees with the equivalent AIRS result. The observed effect may be decreased or at least more aggressive quality flagged in a future release of the CrIS calibrated radiances. If AIRS and CrIS were not in the same orbit at the same time, one might interpret the observed differences as evidence of a “climate change”.