Agree with those practising good airmanship on here, too many factors for a simple one-option solution.
- determine conditions on landing;
- determine options to vacate, the first one is not always best even if a runway occupancy reduction can be achieved;
- determine flap/brake combinations for each option to vacate safely;
- determine if any flap/brake combination can make use of idle reverse without affecting turnaround schedule;
Decision is now in crew hands...
In regards to money saving and fuel reduction, the order (737) in which I prefer to opt:
- Idle flap, 30, using auto-brake 1 or 2, if possible
- Idle flap 40 if 30 requires too much cooling time or is unable to make a planned exit
- Increase auto brake if required requiring second detent reverse on most landings
When considering configuring at 4-5nm, fuel savings can then be summarised as:
- Flap 30 saves ~10-15kg
- Idle reverse saves ~50-70kg
Sometimes only one or none of the above choices can be made for safety or operational reasons, sometimes they are not mutually exclusive.
In our operation, there seems to be a prominent lack of knowledge when it comes to fuel saving and costs.
The amount which can be saved can widely vary on operational techniques, if taught correctly in the good airmanship classes during training, significant savings on a (large) fleet are possible.