(Not company call-signs)
Wikipedia gives the following guidelines
- Eastbound and northbound flights are traditionally assigned even numbers, while westbound and southbound flights have odd numbers.
- Other airlines will use an odd number for an outbound flight and use the next even number for the reverse inbound flight.
- For destinations served by multiple flights per day, numbers tend to increase during the day.
- Flight numbers of less than three digits are often assigned to long-haul or otherwise premium flights.
- Flight number 1 is often used for an airline's "flagship" service.
- Four-digit numbers in the range 1000 to 4999 typically represent regional affiliate flights.
but doesn't give any references (anybody have any?).
Assuming these are (generally) true, are there common strategies for how airlines number flights in a 'class'? For example, is there any significance between DAL310 and DAL342? AAL4569 and AAL4135?
Or is the standard method generating a (bounded) random number?