In the aviation sector, taxi refers to specific operations during the flight phases (see figure hereafter), when the aircraft runs slowly on the airport ways (apron and so-called taxiways) to reach the take-off runway or to reach the gates.
Air taxis can also refer to aircraft activities that are quite similar to the taxi activities of road vehicles and during which an aircraft provides an on-demand service for the customer.
(EMEP/CORINAIR 2006, Emission inventory guidebook, Group 8: Other mobile sources and machinery)
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