Speed drop at normal flap deploying.

[Ourgas2 3]

Hi all,Some help please on a question regarding the approach phase using VNAV.While descending, on VNAV mode, deploying a flap setting causes the speed to drop very much (as seen in the magenda indication in the PFD) and does not match the indicated FMC speeds. Noted that flaps are deployed within their operating speeds.Why is the speed lowering and does not follow the FMC indicated speeds?Thanks,Christos

[Turbine777 13]

Hi all,Some help please on a question regarding the approach phase using VNAV.While descending, on VNAV mode, deploying a flap setting causes the speed to drop very much (as seen in the magenda indication in the PFD) and does not match the indicated FMC speeds. Noted that flaps are deployed within their operating speeds.Why is the speed lowering and does not follow the FMC indicated speeds?Thanks,Christos

Once you deploy slats and next available landing flaps of normally 15, it automatically lowers your speed to about 179, 180ish. This is normal and expected behavior. Additional flaps being extended will result in the FMS further reducing your speed for your selected landing speed.

[Check_Airman 3]

The FMS has a deceleration schedule built in. If you're faster than the speed the FMS wants and FMS SPD is engaged, the minimum speed will be shown by a hollow pink circle, and the FMS will maintain that speed. The target speed will be a filled pink circle, and the plane will slow to that speed once you extend the flaps.Paul

[Guest Freighthog MD11]

The FMS has a deceleration schedule built in. If you're faster than the speed the FMS wants and FMS SPD is engaged, the minimum speed will be shown by a hollow pink circle, and the FMS will maintain that speed. The target speed will be a filled pink circle, and the plane will slow to that speed once you extend the flaps.Paul

My 2 cents...The minimum speed real life is stick shaker plus 20knots, stick shaker is the top of the yellow T on the speed scale just add 20 to that and you will be safe. Sometimes in the real airplane," lets say on a speedy approach" the FMC speeds bug is not fast enought in recalculating the new speeds maybe youre in a turn, you have to know what the min speed is for your configuration.

[KCA9304 0]

My 2 cents...The minimum speed real life is stick shaker plus 20knots, stick shaker is the top of the yellow T on the speed scale just add 20 to that and you will be safe. Sometimes in the real airplane," lets say on a speedy approach" the FMC speeds bug is not fast enought in recalculating the new speeds maybe youre in a turn, you have to know what the min speed is for your configuration.

Lets add 2 cents more.. Stick shaker plus 20 kts and top of the amber band (T), which is Vmin, plus 20 kts are not the same speeds. Maintaining a speed of 20 kts above this Vmin while manouvering and configuring towards a landing configuration is normal practice in real life, because the Vmin amberband is g-load dependent. Meaning it will indicate a higher value during turns as compared to wings level situation.It's a pitty, but in the simulation this Vmin remains unchanged when g-load changes. Only the red stick shaker indication is linked to the g-load. So the FMC speed (re)calculation is a rather fixed value, in the simulation that is.Regards,Harry

[Gary A 8]

Not to hijack the thread but on departure on flap retraction pitch seems to lag to air speed. Example I takeoff (I use FS2Crew) PFD is calling for 175kts, engage profile and navigation, engage auto flight, I retract to flaps 15 by schedule in PFD, plane continues to pitch at such a rate that air speed continues to drop to point where auto stall kicks in. After a while pitch decreases, airspeed begins to increase to point where I can continue to retract flaps. I shouldn

[Gary A 8]

Not to hijack the thread but on departure on flap retraction pitch seems to lag to air speed. Example I takeoff (I use FS2Crew) PFD is calling for 175kts, engage profile and navigation, engage auto flight, I retract to flaps 15 by schedule in PFD, plane continues to pitch at such a rate that air speed continues to drop to point where auto stall kicks in. After a while pitch decreases, airspeed begins to increase to point where I can continue to retract flaps. I shouldn