Flight Instruments, Displays -EFIS System Description 737 Operations Manual
Next Flap Placard Speed
The next flap placard speed uses the same symbol as the high speed buffet limit. If the airplane is in the air, and flaps are lowered, the hollow yellow bar extends from the high speed end of the speed tape. The end of the hollow yellow bar now represents the placard speed for the next normal flap position. Next flap placard speeds are displayed only for those flap positions that would normally be used during an approach and landing. The next flap placard symbol is blanked when current flap position equals the selected landing flap configuration on the FMC/CDU APPROACH REF page or when the flaps are being retracted.
Flaps Up Maneuvering Speed
Flaps up maneuvering speed is indicated by a small green circle on the speed tape. This speed is an output of the stall warning computer and is based on the actual gross weight as computed by the FMC. It represents the best airspeed (climb or driftdown) for an airplane in the clean configuration. This function is not enabled until flaps are up.
V1 (decision) Speed
V1 speed is depicted by a green “–1” located opposite the V1 speed on the speed tape if the V1 speed is within the displayed range. If the selected V1 speed is not within the displayed range, a green “V1” with the numeric value of the V1 speed is displayed at the high speed end of the speed tape.
Before the V1 speed is displayed on the speed tape, V1 must be entered on the FMC/CDU TAKEOFF page.
VR (Rotation) Speed
VR speed is depicted by a green “–R” located opposite the rotation speed if the rotation speed is within the displayed range. The “–R” symbol is blanked if the rotation speed is not within the displayed range.
Before the VR speed is displayed on the speed tape, VR must be entered on the FMC/CDU TAKEOFF page.
Flight Instruments, Displays -EFIS System Description 737 Operations Manual
VREF (Reference) Speed
The Vref speed is represented by the “–R” symbol. The FMC/CDU APPROACH REF page displays Vref speeds based on the current gross weight for three landing flap settings. The flight crew may select the FMC computed speed or manually enter another value into the field corresponding to the desired landing flap configuration. This speed will then be transmitted by the FMC, and the symbol generator will display the “–R” symbol opposite that speed on the speed tape.
Note: The FMC updates the computed Vref speeds (small–size characters) as fuel
is burned off based on fuel totalizer inputs. A Vref value does not update
once it has been selected for transmission to the speed tape. If the flight
crew manually inserts a gross weight on the APPROACH REF page, the
FMC computed Vref speeds will be based solely on the manually entered
gross weight as long as the APPROACH REF page remains in view. A
manually entered gross weight is not updated as fuel is burned off.
Minimum Flap Retraction Speed
Minimum flap retraction speed is indicated by a green “–F” on the right side of the speed tape. This speed is computed by the stall warning computer. It represents the speed that will provide the minimum maneuver speed (depicted by the end of the low speed yellow bar) for the next normal flap position (i.e., flap positions 5, 1, or UP only). The display will respond to the effects of extending the flight spoilers.
Minimum Maneuvering Speed
Represented by the end of the low speed hollow yellow bar. If the airplane is at
low altitude, and is flown at this speed, a .3G maneuver margin to stick shaker is
provided. This would allow for a 40–degree bank turn while maneuvering in level
flight.
If the airplane is at high altitude and is flown at the minimum maneuver speed, a
.3G maneuver margin to low speed buffet is provided as opposed to a .3G to stick
shaker margin. Since the stall warning computer uses FMC gross weight to
calculate the minimum maneuver speed at high altitudes, this symbol is not
displayed at high altitude if the FMC gross weight is not available.
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本文鏈接地址：737-300機(jī)組操作手冊(cè)Flight Crew Operations Manual FCOM 3(17)
