royskaria: why is it so important that the aircraft is still in production? Why does that criterion win over - for example - lease cost, operating costs or reliability?
Yes, an in-production aircraft may be the ideal situation, but you'd be excluding several potentially good candidate aircraft by imposing that condition. Aircraft such as the B1900 and Saab 340 were popular enough, and enough are still in service, that they are still supported by their manufacturers, even though they're not in production. (In many cases, e.g. Saab 340 or Jetstream 41, the manufacturer owns a lot of the aircraft and leases them out, and therefore has a strong incentive to keep the type flying and supported.) I think where a greater support problem lies is in the case of aircraft whose original manufacturer is no longer around (e.g. Dornier 328).
Brgds
C.