737-800 & 160KIAS to 4D

[TotalBeginner]

This is a question for anyone flying the 737-800.

1) What is the feasibility of being able to fly at 160KIAS to 4DME with the gear up at high landing weights? Is this possible with flap 10, or can it only be achieved with gear down, flap 15?

2) When selecting TAI on during the latter part of the descent / early approach, does the resultant approach idle have much impact on the aircraft's ROD?

[de facto]

1) What is the feasibility of being able to fly at 160KIAS to 4DME with the gear up at high landing weights? Is this possible with flap 10, or can it only be achieved with gear down, flap 15?

At high weights,i believe 170 kts is about minimum for flaps 5 ,the use of flaps 10 will not allow you to decrease the speed,so gear down/flaps 15 is the only config.
In any case you will be on the glide or on a -3 deg path so you wont have a problem with noise.
2) When selecting TAI on during the latter part of the descent / early approach, does the resultant approach idle have much impact on the aircraft's ROD?

Not much inpact but enough for Boeing to include the option to insert Level at which the TAI will be switched ON then OFF in the FMC desc prog page.
Obviously the longer you use TAI the larger effect,but nothing to worry about.
If you plan to use TAI,set your FMC best you can and your VNAV descent will be closer to its optimum path.

[owl-attack]

the use of flaps 10 will not allow you to decrease the speed,so gear down/flaps 15 is the only config.

De Facto. You mean with flaps 10 selected the flap manoeuvring speed will not decrease [If flaps 5 Manoeuvring speed is 170 kts, selecting Flaps 10 wont allow me to select a value lower than 170 kts?] But why ?

[de facto]

De Facto. You mean with flaps 10 selected the flap manoeuvring speed will not decrease [If flaps 5 Manoeuvring speed is 170 kts, selecting Flaps 10 wont allow me to select a value lower than 170 kts?] But why ?

Flaps 5 and 10 have the same maneuvring speed (vref 40+30).
Flaps 10 is used sometimes to increase descent rate over a short period of time,for example turning to intercept loc to avoid deploying the speedbrake in a turn and/or selecting the landing gear too early.

[owl-attack]

Flaps 5 and 10 have the same maneuvring speed (vref 40+30).

You are right I just confirmed that with the FCTM chapter 1

Flaps 10 is used sometimes to increase descent rate over a short period of time,for example turning to intercept loc to avoid deploying the speedbrake in a turn and/or selecting the landing gear too early.


That's a good info for me .... but I just read in FCTM chapter 4 (under the speedbrakes section) It says " Flaps are normally not used for increasing the descent rate

But it can still be done right, better than - increasing the roll rate while turning to intercept the LOC by extending speed brks or putting the gear down and minimizing passenger comfort and decreasing door life:ok:

[de facto]

That's a good info for me .... but I just read in FCTM chapter 4 (under the speedbrakes section) It says " Flaps are normally not used for increasing the descent rate

Correct and speedbrakes should also be avoided while flaps are out.It is an appropriate alternate solution to using speedbrakes if excess speed is not added in the mix:E
Excess speed for a certain flaps setting is not good,ie flaps 10 and 210 kts..
20 kts above the maneuvring is absolute personal limit.