The A/S on the PFD consistently shows 40-45kt when the aircraft is stopped, indeed right after loading the aircraft. I have seen similar A/S values after rollout and coming to a complete stop on the taxiway as well - Wind in the accompanying screenshot is 222/10, and the airplane is sitting at the gate.I have seen this behavior in the base package, SP1 and 600/700 addon package. Anyone else see this? Is there an explanation?

That is correct for a Boeing 737NG.You will also notice that it defaults to 100 kts on the MCP speed slector.You cannot dial in a lower speed !If you could, people would be tempted to use it for taxing. ONE of the reasons why Boeing chose 45 kts is that when you engage TOGA it commands 10 degrees nose down.At 60 knots it commands 15 degrees nose up and starts the count from the preset 45 knots upwards.( you can always see your Ground Speed on the GS readout just below the speed tape)Hope this helps.Fred.

Ah! Thanks a lot for that explanation, although I'm not sure I understand why it would be programmed that way. I'm surprised the systems aren't sophisticated enough that they can always display TAS as one would expect and use weight-on-wheels + TAS to command pitch when TOGA is selected. So much to learn with this bird, but I must say I'm enjoying every moment with it.

Ah! Thanks a lot for that explanation, although I'm not sure I understand why it would be programmed that way. I'm surprised the systems aren't sophisticated enough that they can always display TAS as one would expect and use weight-on-wheels + TAS to command pitch when TOGA is selected. So much to learn with this bird, but I must say I'm enjoying every moment with it.

Why would you want to use TAS? IAS is what matters, especially when at takeoff/landing speeds.

Ah! Thanks a lot for that explanation, although I'm not sure I understand why it would be programmed that way. I'm surprised the systems aren't sophisticated enough that they can always display TAS as one would expect and use weight-on-wheels + TAS to command pitch when TOGA is selected. So much to learn with this bird, but I must say I'm enjoying every moment with it.

Noone of the plane I saw uses TAS as principal indication for speeds, all uses CAS normally renamed and used as IASAutomatic take off is not provided on the 737, and I think on most of the planes in the world.Remember that NG is simply a soon of this:

I of course meant IAS...

Ah! Thanks a lot for that explanation, although I'm not sure I understand why it would be programmed that way. I'm surprised the systems aren't sophisticated enough that they can always display TAS as one would expect and use weight-on-wheels + TAS to command pitch when TOGA is selected. So much to learn with this bird, but I must say I'm enjoying every moment with it.

A lower limit of 40-50 knots is typical for most airspeed indicators - either the old-fashioned analog kind found in GA aircraft, or the sophisticated digital air data computers in airliners.In the case of the mechanical units, its a trade-off between sensitivity and ruggedness. An airspeed indicator is really nothing more than a pressure gauge, and the ram air pressure in the pitot tube corresponding to speeds less than 45 knots is quite low - (less than one p.s.i.)It definitely is possible to construct a sensitive indicator, capable of accurately measuring pitot pressures down to "zero" knots. You will typically find such airspeed indicators on aircraft that (by design) are capable of sustained flight at very low airspeeds - specifically helicopters, but also on sailplanes and ultralights.The drawback is that such sensitive indicators tend to be more expensive, and are also more delicate in terms of their internal mechanism - i.e. more easily damaged by things like excessive vibration, or an accidental over-pressure condition.Air data computers found in larger aircraft, use solid-state pressure transducers to measure pitot pressure, which are quite rugged, but even so, there is little point in designing in the extra sensitivity required to measure extremely low airspeeds, since such aircraft can't fly that slow, and one can always use the GPS or IRU-derived groundspeed readout to measure taxi speed.

A lower limit of 40-50 knots is typical for most airspeed indicators - either the old-fashioned analog kind found in GA aircraft, or the sophisticated digital air data computers in airliners.In the case of the mechanical units, its a trade-off between sensitivity and ruggedness. An airspeed indicator is really nothing more than a pressure gauge, and the ram air pressure in the pitot tube corresponding to speeds less than 45 knots is quite low - (less than one p.s.i.)It definitely is possible to construct a sensitive indicator, capable of accurately measuring pitot pressures down to "zero" knots. You will typically find such airspeed indicators on aircraft that (by design) are capable of sustained flight at very low airspeeds - specifically helicopters, but also on sailplanes and ultralights.The drawback is that such sensitive indicators tend to be more expensive, and are also more delicate in terms of their internal mechanism - i.e. more easily damaged by things like excessive vibration, or an accidental over-pressure condition.Air data computers found in larger aircraft, use solid-state pressure transducers to measure pitot pressure, which are quite rugged, but even so, there is little point in designing in the extra sensitivity required to measure extremely low airspeeds, since such aircraft can't fly that slow, and one can always use the GPS or IRU-derived groundspeed readout to measure taxi speed.

Very good answer friend.. I was about to explain this, but you did first!