Fmc Vnav Profile

[jimimac 19]

hi when using the fmc in the 737 i have path selected but always seem to get a drag required message so i switched to using speed and havent had any problems, do most pilots use speed or path with the 737fmc. thanks, jim

[downscc 1,327]

The drag required message is advisory only. You will usually get this if tail winds are greater than forecast (assuming you put values in the descent forecast).There are a lot of threads on VNAV descents, and both advocates of VNAV and SPD/VS controlled descents. It depends on your flying technique. I personally prefer to control my descents in both Boeings with the MCP controls (SPD VS) and only use VNAV for climbs. However, the MD11 system is quite amazing in it's ability to generate a flyable profile and stick to it, and in this case I definitely use PROF.

[cavaricooper 2,615]

The drag required message is advisory only. You will usually get this if tail winds are greater than forecast (assuming you put values in the descent forecast).There are a lot of threads on VNAV descents, and both advocates of VNAV and SPD/VS controlled descents. It depends on your flying technique. I personally prefer to control my descents in both Boeings with the MCP controls (SPD VS) and only use VNAV for climbs. However, the MD11 system is quite amazing in it's ability to generate a flyable profile and stick to it, and in this case I definitely use PROF.

I'd offer the alternate viewpoint that VNAV produces the best seat mile cost and the best passenger comfort and the best safety speed control- therefore I am a big fan of utilizing VNAV to the IAF. Unfortunately, the sadist in me enjoys building or modifying approaches and gets particular enjoyment from last minute APP revisions ;). As one of our RW pilots (Cowpatz) pointed out Boeing spent an inordinate amount of time on the VNAV portion, so that we would actually use it. The PMDG VNAV functionally has gotten exponentially better with product releases so I would suggest you would be very happy with the VNAV in the 747 or in the MD-11 (PROF)- even the 737 is more than adequate.All that said, Dan is correct that (per Bill Bulfer's excellent manual) there are times for VNAV (strategic) and then times for MCP flying (tactical). ATC instructions for example are best handled heads up with MCP input.Develop familiarity with your airframe, and enjoy- no matter what- and should you get the chance- take the fat girl for a spin- your heart will never be the same :).

[jimimac 19]

thanks for the reply, im awaiting the release of the md11 for fs9 before deciding on the queen of the skies or md11 thanks, jim