B737-300 Auto GA and weird ASI Bug movement
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B737-300 Auto GA and weird ASI Bug movement
Wouldn't mind some ideas on this query. B737-300 simulator in auto-pilot GA Mode. Refer FCOM Vol 2 page 4.20.17 in the manual I have.
With a 50,000 kgs AUW and TOGA is pressed the aircraft does it's GA and flaps are selected immediately to 15. Pos climb gear up. The airspeed bug on the mach/airspeed indicator moves to 155 knots in our simulator which is the manoeuvering speed for Flap 15. The manoeuvering speed for 50.0 tonnes Flap 15 is 150 knots yet ours goes to 155 knots. The theory being once the aircraft passes 150 knots it is normal to select Flap 5, whereupon the ASI bug slowly moves to 170 knots. Once again as the aircraft passes 170 knots, we select Flap 1 and sure enough the ASI bug should move to 190 knots which is the manoeuvre speed for that flap setting.
BUT - our simulator ASI bug goes right through to a reading of 210 knots even though the flap lever is selected to the Flap 1 slot.
Is this a simulator fault? Because one would think logically the ASI bug should stop at 190 knots seeing as the flap lever is set at Flap 1.
To further cause puzzlement, the FCOM described earlier states "FD pitch then commands maneuvering speed for each flap setting based upon maximum weight calculations.
.
The max weight conditions I presume mean structural of 61.4 tonnes. And that means the manoeuvering speeds are 160 knots for Flap 15, 180 knots for Flap 5 and 200 knots for Flap 1 and finally 220 knots clean. So, even though our specific AUW is set at 50.0 tonnes for training in the simulator, in theory the ASI bug that moves to reflect manoeuvre speed for each flap setting during the AP Go-Around, should be approximately 10 knots higher than we are getting in the sim. (FCOM Vol 2 refers)
And why would the ASI bug move directly to near the 210 knot mark when the flaps are at Flap 1? Defective simulator maybe?
Sorry if this all seems rather convoluted, but its the best I can do at this time of night in OZ.
With a 50,000 kgs AUW and TOGA is pressed the aircraft does it's GA and flaps are selected immediately to 15. Pos climb gear up. The airspeed bug on the mach/airspeed indicator moves to 155 knots in our simulator which is the manoeuvering speed for Flap 15. The manoeuvering speed for 50.0 tonnes Flap 15 is 150 knots yet ours goes to 155 knots. The theory being once the aircraft passes 150 knots it is normal to select Flap 5, whereupon the ASI bug slowly moves to 170 knots. Once again as the aircraft passes 170 knots, we select Flap 1 and sure enough the ASI bug should move to 190 knots which is the manoeuvre speed for that flap setting.
BUT - our simulator ASI bug goes right through to a reading of 210 knots even though the flap lever is selected to the Flap 1 slot.
Is this a simulator fault? Because one would think logically the ASI bug should stop at 190 knots seeing as the flap lever is set at Flap 1.
To further cause puzzlement, the FCOM described earlier states "FD pitch then commands maneuvering speed for each flap setting based upon maximum weight calculations.
.
The max weight conditions I presume mean structural of 61.4 tonnes. And that means the manoeuvering speeds are 160 knots for Flap 15, 180 knots for Flap 5 and 200 knots for Flap 1 and finally 220 knots clean. So, even though our specific AUW is set at 50.0 tonnes for training in the simulator, in theory the ASI bug that moves to reflect manoeuvre speed for each flap setting during the AP Go-Around, should be approximately 10 knots higher than we are getting in the sim. (FCOM Vol 2 refers)
And why would the ASI bug move directly to near the 210 knot mark when the flaps are at Flap 1? Defective simulator maybe?
Sorry if this all seems rather convoluted, but its the best I can do at this time of night in OZ.
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I don't have the FCOM to look at, but is it possible that the change in commanded speed to 'max weight' factoring only occurs at Flap1 settings and that your sim has some vestigial memory of the 'heavyweight' 400's with 62.8T+/210 Flap1/230 clean?
I think the simulator is OK. I think the ASI speed for GA is based on the Max weight of the B737-300 as a series of aircraft (i.e. 139500 lbs or 63,276 kgs) not your tail number specific max weight. However weird things happen to aircraft operations in Aussie so it maybe a "we know best" modification.
If you are using the speed tape then the "next normal" flap can be selected when above the "F" marker. The block speed table is just a very rough guide if you are not using the speed tape.
If you are using the speed tape then the "next normal" flap can be selected when above the "F" marker. The block speed table is just a very rough guide if you are not using the speed tape.
