747 Landing technique
 

For the final approach say from 1000ft down to say 100ft, what technique is used on the 747?

Is it the "point and power" technique whereby Pitch attitude controls rate of descent and Power controls speed...... OR.....

Is it the other technique (don't know the name) whereby Pitch controls speed and Power controls rate of descent?

Thanks.

No 1, aim at the aim point and control speed with power.

Yikes, that question brings back memories of pounding the circuit at CFS, and many happy "flarepath" demos and the like.... .........


Anyhow pitch/roll controls the aim point, power for speed.

Suppose it all depends on where you come from....

Where I come from power controls your ROD (or ROC for that matter via excess thrust) and pitch your speed.....

Then again on airliners, it all seems to be a bit of a blur cause of the FD and autothrust, in my experience.

But Raw data, manual flying, manual thrust.....pitch for speed and power for ROD for me.....;)

Maybe they're all linked?

At GS intercept select the attitude for the 3 degree descent and reduce the thrust to give you the correct ROD. The attitude controls the speed and the thrust the ROD. Increase the thrust and to maintain the correct airspeed make a small attitude adjustment hence the ROD will reduce.

From DH to touchdown it reverses: the control column manages the flight path and the thrust the speed.

SO the answer is both :{

AFAIR it many Moons ago in some "decending" exercises on the JP ( basic Jet) we taught power controls ROD and attitude controls airspeed, (Oscar Yankee's point) ...and that was the technique to be applied at medium level and was also the one to be used around the finals turn - e.g if you were low half way round finals you applied power to reduce ROD and raised the noise to control speed.

However once rolled out on finals the teaching was to point at the numbers and control speed with power. There was a bit of angst and discussion at times about teaching Blogs this apparent change in technique but at the end of the day as long as you realise pitch / power is interrelated, as we all know, then I guess we use whatever "method" works for us.

Frankly I reckon you are stuffed if you end up thinking too much about it - then again you should see/feel some of my landings on the 744 :ooh:

Power + Pitch = Performance. Trim the pitch to hold the speed and set the power to maintain the descent rate. Adjust both as necessary.

If you're having to consciously think about "technique" such as this on final, maybe you shouldn't be flying a 747!

I agree Intruder. Don't really think about it just do it. The classic seems to like abut a 3 degree pitch on a 3 degree glideslope at 25 flap. If you are flying a higher pitch to hold glideslope, just add 5 knots and vice versa.

If you watch the autoland at work you will note that the autothrottle [thrust levers] movements always correspond to airspeed variations, and elevator for pitch.

Intruder says it all. For a constant angle final approach in still air conditions, you need a combination of power and pitch - get it right early on and you won't need to vary either, but remember that an increase in power will result in an increase in pitch and vice-versa. After a few attempts on the simulator, it will become secon-nature.
Glueball is quite correct in the demonstration of an autoland.

To achieve the correct glidepath/glide-angle, pitch controls speed and power controls rate of descent.

Once on the correct glidepath/glide angle, power controls speed and pitch/bank points you at the landing point.

hhhmmm.. power for RoD.... something about swept wing jets and the aerodynamics of the drag curve which makes me cringe at the idea, BUt each to their own. You tend to use both anyway, simultaneously!

To fast pitch up, higher rate of descent, more power, still to past pitch up, even higher rate of decent, more power etc etc etc. :sad: I feel for the people down the back.

Trim, then pitch 4 speed, power for RoD works until I screw something else up!

Talk about dead men walking!! :eek:

Swept wing jets ALWAYS require pitch for aiming point and thrust for speed when on approach.

End of story. :ugh:

pitch/power
 

Gentlemen (and ladies)

Am surprised by your confusion. On a light aeroplane without much in the way of excess power and certainly very little inertia then the favoured technique was always to control the speed with pitch and the rate of descent with power. I was taught this in the airforce and taught it myself. Can you imagine, however, just how uncomfortable this would be to your pax in the back of a highly powered and heavy (ie loads of inertia) widebody jet?! Remember, inertia is the reluctance of a body to change, in this case, its speed and would need a pretty impressive pitch change to achieve this effectively in, say, a 200 ton aeroplane. We all, probably instinctively, point at the aiming point and use thrust to achieve the desired speed on anything from a turboprop upwards. It is just that you have 'forgotten' that you do it and you do it instinctively. It is also true that power and pitch are totally inter-dependant so that,although both methods work out, only the thrust equals speed and pitch equals descent rate is the really appropriate method to use for large inertia aeroplanes.

I'll standby for some flak.....

I fly nothing bigger than a 172 and to be honest I have never really thought too much about this until now. On final I make pitch and power corrections without consciously thinking about it. in fact, after contemplating this thread, I'm afraid I'll over think my next approach and bugger it up!

But then this was a 747 thread...I'll get my coat.

I just kinda do it, landing that is.:ouch:

Crosswind landings in a 747 or similar heavy jet. The inertia of these types must cause a handling problem to pilots learning to handle crosswind landings.
Assuming the flare manoeuvre to touch-down is 3-5 seconds it means you have less than that time to "kick-off" drift (I know that is a wrong term but you know what I am getting at presumably) to ensure the aircraft touches down aligned with the runway centre-line - ie nil drift angle. With such a large mass is it normal therefore to keep the thrust up for as long as it takes for the nose to swing around in alignment, and then close the thrust levers after touch-down?

The crosswind landing technique is probably the same on a 747 or similar wide body as a B737 right down to a Cessna 172. Of course the inertia of the 172 makes it easy to align with the runway with a touch of rudder during the flare. But I guess it takes several seconds to align a 747 with the centre line assuming sat max crosswind angle. I have not flown a 747 which is why I am curious as to the time in seconds needed to complete the alignment procedure to nil drift.

This technique has been talked about quite a bit but when you work out how much you move the wheels in the vertical plane by doing this, it comes out as inches over a few seconds: not likely to make much difference. I think what might be happening is that you are touching down at a lower pitch attitude, so when the ground spoilers deploy there is less of a change in lift and not as much for the oleos to absorb all in one go; also, by the time the GS do deploy, most of the travel has been used up. Watching aircraft land from the holding point, you often see what appears to be a perfect touchdown spoilt by spoiler deployment as the plane sits down on the bumpstops...

My theory is that in many aircraft, the smoothest landings result from having a certain (low) rate-of-descent when you touch down, which is progressively removed as you sink down on the suspension, leaving the airframe at rest in the normal axis w.r.t. the ground and at the 'taxiing' level of extension on the oleos. :8