PACE-PAX is a field campaign to support validation of PACE data products following launch. Validation requires a strategy of varied and extensive measurements, as discussed in the PACE Science Data Product Validation Plan. PACE-PAX is one component of the PACE validation plan, specifically addressing validation of new data products. Because these products are often the result of multi-parameter retrieval algorithms, focused and extensive measurements will be made as part of a dedicated field campaign. This campaign will use a robust suite of instruments deployed on aircraft, which will fly in coordination with ground and ocean-based observations and the PACE satellite overpass. It will be conducted roughly six months following the launch of PACE.