I strongly recommend the use of OPEN DES at any altitude except from 2000' agl down to say 35-20' agl (depending on type and state of energy). At 35-20' agl I strongly recommend the use of OPEN DES... it might NOT say "open des" on the PFD, but something like THR IDLE... but if you don't "open descend" it, the landing might be long... and there is an inherent risk of being called a RETARD.
On a more serious note: OPEN DES is like converting to glider mode and controlling the ROD with speed through the elevator.
Rule of thumb (probably stated before):
- above profile (not glideslope) use OPEN DES
- below profile use VS (again, this depends on your energy state as well)
Everybody has their own style... some like to burn fuel, others like to preserve as much they can with the same level of safety (SA), economy, puntuality and pax comfort in that order (or possibly swapping the middle two).
small edit
Last edited by square leg; 3rd November 2007 at 15:44.