approach to touchdown - pitching and trimming

[code0]

Greetings!

Was wondering if somebody could help me out with following clarification

When an aircraft, lets say 737NG enters into final approach from about 20NM at an altitude of 3,000ft at about 175KIAS and on a CAT 1

- Does the pitch nose-angle go negative or is it straight? and the descend is done by a combination of elevator trimming, lift dumpers ?

- is only nose up or positive pitch happens at the flaring?

simply what am asking is on final approach to touch down what is the attitude of the pitch angle?

I know depending on above or below glide slope the pitching can be changed, but in this instance I am assuming the plane is at the correct glide slope!

Thanks a lot!

Code0

[AerocatS2A]

First up you'd normally be at 3000 feet at 10nm not 20nm.

As to your question, provided everything remained the same, that is gear/flap/slat settings and speed remained the same then nose must be pitched down relative to where it is for level flight in order to commence a descent. That is basically done with the elevators. Elevator trim is a secondary function that keeps the nose where you put it. Lift dumpers/spoilers are not the primary means of descending and would normally only be used to help slow down or to fix a situation where you are too high.

Disclaimer: Not a 737 pilot, but this stuff is the same for nearly everything.

Further info if you can follow it. Flaps and slats change the effective angle of incidence of the wing (the angle between the wing and the longitudinal line of the fuselage.) Flaps increase it and slats decrease it. Having more flap extended will give a lower nose attitude for a given speed and flight path, extending slats will give a higher nose attitude. For every change you make to flaps and slats you need to adapt to a different nose attitude.

[Occy]

No-one really thinks that much in terms of "pitch angle" (unless you have unreliable airspeed indications). Having said that, a normal pitch angle on final approach for a big jet is about 2-2 1/2 degrees nose up.

20NM at an altitude of 3,000ft at about 175KIAS

is a bit low bro. A normal speed/altitude at 20NM from touchdown is 250KIAS/5,000ft

[Pub User]

On the 737NG, the pitch angle on a normal. stabilized Flap 30 approach is about 1 degree nose-up. For a Flap 40 approach about 0.5 degrees nose-down.

[CS-DDO]

Check the "unreliable airspeed" tables, it's generally a good indication for power setting and pitch.