Flight number 1 is often reserved by airlines for their 'flagship' routes. For example BA 1 (British airways), is the London - New York route, previously flown by the Concorde. Can you guess the second destination for all these airlines on their routes with the flight number 1?
According to Wikipedia and FlightStats, As of 8 September 2018.
In some instances the 'From' and 'To' destinations may be flipped to avoid giving away the answer, since the 'To' destination is the airline's hub.
It is sufficient to type in city names and not airport names, even for cities with multiple airports.