This study was performed to measure temperature and pressure conditions observed by standard packages in the FedEx “Next Day Air” network and the environmental conditions of Passenger Aircrafts. To measure the single parcel environment, two destinations known to be served by non pressurized feeder and pressurized aircrafts in the United States, San Luis Obispo, California and Twin Falls, Idaho, were used to represent higher altitude paths. Test packages (12 x 12 x 12 in) containing one MadgeTech PRTemp110 recorder were shipped Priority Overnight by FedEx to each destination from East Lansing, Michigan. For six weeks, two test packages were shipped to each destination. To measure the Passenger aircraft environment, test packages (5 5/8 x 4 3/8 x 2 3/8 in) were both carried in the passenger cabin and checked with luggage. Results show temperature ranges, pressure drop rates, and maximum altitudes observed in the FedEx environment and in commercial passenger flights. This study compares these results with the ASTM D6635 test procedure with respect to suggested test pressure, pressure change rate, temperature, and test duration.