This SAE Aerospace Recommended Practice (ARP) describes the continuous sampling and analysis of gaseous emissions from aircraft gas turbine engines. The measured gas species include carbon monoxide (CO), carbon dioxide (CO₂), nitric oxide (NO), nitrogen dioxide (NO₂), hydrocarbons (HC) and water vapor (H₂O). This ARP excludes engine operating procedures and test modes, and is not intended for in-flight testing, nor does it apply to engines operating in the afterburning mode.