The term AIRPORT SCHED. ABBR. is an abbreviation for airport scheduling abbreviations. The two abbreviations used in this crossword are ARR and ETA. ARR stands for 'ARRIVAL' and is used to indicate when a plane is expected to arrive at an airport. ETA stands for 'Estimated Time of ARRIVAL' and is used to indicate the estimated time that a plane will arrive at its destination. Both of these abbreviations are commonly used in airport scheduling and help to ensure that flights arrive and depart on time.