With code first in mind you can try

    [InverseProperty(nameof(FlightSchedule.AirportArrival))]
    public ICollection<FlightSchedule> ArrivalAirports { get; set; }
    [InverseProperty(nameof(FlightSchedule.AirportDeparture))]
    public ICollection<FlightSchedule> DepartureAirports { get; set; }