Landing techniques

[GraemeK]

My first day back at the controls today after 6 weeks away! And one fairly reasonable landing after a few ordinary ones. So it got me thinking about how we're taught to land.

 

In her excellent blog, DarkSarcasm relates the technique she has been taught (and I've experienced it with the same instructor). Basically, it's control airspeed with power and flightpath with elevator.

 

With other instructors, I've been taught the opposite - ie control flightpath with power and airspeed with elevator.

 

At the end of the day, I think both come down to the same thing - thus by the method I've been taught, if the aiming point is going up the windshield (undershoot) then I apply power to reduce descent rate and backpressure to control speed. By the other method, I would apply backpressure to reduce descent and power to maintain speed. Same result - but the psychology is different.

 

Do people have a preference? I'm inclined to the control flightpath with power and airspeed with elevator approach, because it instills in my mind that the elevator is not necessarily the up/down control (and sometimes I need reminding, for instance when I level off I was inclined to just pull back on the stick and forget that power is needed to arrest the descent). In an emergency, if I was losing height rapidly, I'd like throttle to be my instinctive response rather than hauling back on the stick.

 

 

[Yenn]

I believe you should use the elevator to control speed and throttle to control descent rate. But, and it is a big but, when you are coming in to land you can get very close to the backside of the power curve, where throttle will be required to increase speed, before any further elevator can be used to raise the nose. That is what you prefer, but if the speed is high enough, there should still be enough left to control the flare without using the throttle. This has the advantage that throttle is not used when it is most likely to be unavailable and also hard to control.

 

How easy is it to give just the correct amount of power to arrest the descent? Not too little and not too much.

 

For real ease of control. use the sideslip to control descent rate and it is so easy to relax the controls and reduce the rate of descent.

 

 

[Guest Decca]

Nice input Yenn.

 

Yes GK, two trains of thought for the same outcome. Multi-engine jet jockeys flying low & slow, have one option; fistfulls of thrust to maintain speed, & use the control column to maintain glide path. They are trained accordingly.

 

We, who have one engine, not as slippery as the above, don’t have that luxury. Especially if “one” fails on final.

 

No doubt at least one I know will want to interact here, so I will give him and a few others the opportunity to respond before I go any further.

 

Decca.

 

 

[Guest check-in]

It is not as complicated as some would like to make it. If you have power available, it is power for speed and pitch (attitude) for flight path, ie the stick (ducks for cover as the old WW2 school argue to the contrary). If you fly all powered approaches that way, after a while it just becomes instinctive. This instinct could one day save your life. Only the other day I had a student in my little jet get too slow on a low level base turn. I was being Mr Cool and letting it go to see if he would do anything about it. To the point where the stall warning (stick shaker) gave a little quiver - because we were also turning and a gust came through from the rear quarter (15-20 knot crosswind blowing from the base side, ie up our tail on base leg). With insufficient height to safely lower the nose, a good squirt of thrust had us back up to speed in about 2 seconds flat, while we continued to go where we were aiming to go. Attempting to regain speed by dropping the nose in that situation would have been hazardous as we would have been turning, descending and compounding the problem by undershooting the runway when already close to the ground.

 

When you don't have power - as in a true glide approach or engine failure situation - you have very little control over flight path as you must maintain best glide speed with the only tools you have, basically pitch attitude. Flight path angle may be increased by drag devices such as flaps, extending the gear (if the aircraft has retractable gear) and sideslipping (if the design is conducive to sideslipping), but all the time you will be aiming for that best glide speed with the stick.

 

Contrary to what some would like to believe, all powered aeroplanes work much the same way under power - it is just the speed, control response and inertia that varies. And, once they lose all power they are all gliders. Albeit not as efficient as real sailplanes, more like hang gliders.

 

Pilots of single-engine aircraft really should be proficient in powered and glide approaches to an equal degree, and neglect in particular the glide approach at their peril. Pilots of multi-engine aircraft may not need to be aces at glide approaches, but the occasional practice in a simulator can be a revealing experience.

 

 

[Guest Bert Foster]

Bert

 

In level flight the speed is controlled with power and the flight path is controlled with elevator, right? So why when descending at an angle of only 3.5 degrees from the horizontal would you want to throw that simple principle out the window? Why not just aim the aeroplane at the near end of the runway and control the speed with drag and power? Simple:hug:

 

 

[Simonflyer]

I reckon in the smaller planes you can probably use either method and get away with it, but if you plan to fly something bigger, then get used to flying "attitudes", and use power to go up and down.In the 737 for example, they just hold about 2.5-5 degrees nose high attitude on final and use power to control height(and a bit of speed as well)..Every movement happens a lot quicker in the lighter plane's, but the same aerodymamics apply to everything from a R/C plane to the A380, so in almost all cases i try to use the AoA for Speed, and Power for Up and Down..Just have a read of "stick and rudder".A million year old book on flying that still holds weight in my opinion.

 

And if you plan to fly f14's or the concorde everything is pretty well flown off "Alpha"(AoA), but i dont suggest holding a 15 degree nose up on final in a Tecnam or Jabby!

 

 

[Guest check-in]

Simonflyer, please read DP Davies' excellent book: 'Handling the Big Jets' and reconsider what you have just posted. I doubt that the late Mr Davies has contradicted any published works on high performance flying that preceded or has followed his classic treatise, so I suspect that you may have misinterpreted what the author was trying to get across.

 

When flying jets, the only two usual occasions when pitch attitude (stick) controls speed are in climb where thrust is already at maximum, and in flight idle descent when we aim to save fuel by not using power (so the the aeroplane is just a big glider). At some stage (ideally around 2000 to 2500 feet agl) we have to spool the engines up a) to contain the rate of descent to less than 1000 feet per minute to stabilize the approach - as we don't want it drilling down close to the ground at 3000 fpm (makes judging the flare a bit tricky) - and b) to allow instant engine response if we have to go around. At the point of engine spool-up it becomes thrust for speed and pitch for flight path. Always. No exceptions.

 

A powered approach in a very light aeroplane can be flown the same way and, for the reasons I gave in my earlier post, is worth practising until it becomes instinctive.

 

Another neat feature of this technique is that if you have nailed the speed with power and flight path with stick, all you have to do to land is remove the power and, with very little stick input ( a slight flare to arrest the rate of descent and change the flight path angle to something approximating level flight), you will soon be landing exactly where you want to at just above the stall; therefore still in control. Recently I watched a spot landing competition at a weekend fly-in and the techniques and accuracies were truly sad to behold. Out of maybe 10 participants only one came even close - several, including a RA instructor, did not even get their aircraft on the ground and had to go around because they were too fast. Others held off at 5 to 10 feet, floating to a long landing in a stalled condition and certainly no longer in control of the aeroplane. The conditions were not at all bad so this would seem to indicate that the basics of approach path control and aiming point are not being taught correctly.