landing

landing

Visibility: almost unlimited
Temperature: 19°C
Wind: 330, 18 knots
QNH: 1017hPa
Location: EDAY (Strausberg)
Equipment: “Kilo Sierra” (Cessna 172)

Thunk. The main wheels make contact with the runway at 70 miles per hour. The rubber squeaks a bit but that is normal. I hold the nose up for a bit longer until the aircraft has slowed down so much that the lift disappears and the nose wheel gently settles down. We have transitioned from flight to taxi.

Learning how to land is probably the biggest challenge in learning to fly. The aircraft is designed to fly. It wants to fly. So taking off is relatively easy (throttle forward and off she goes). A good landing requires a smooth transition from flying to not flying and that can only be done with a lot of practice!

My first solo was after about 100 landings with the instructor. Now, after flying for about two years in five or six different aircraft types, I maintain a health respect for the process of landing. And every pilot will have the occasional bad landing, even after years of experience.

A good landing starts with a good approach

It all starts in the pattern. The traffic pattern is a set routing for the approach to any given airport. It enables the pilot to execute the phases of the approach and finally land the aircarft even if he has not been to one particular airport before.

The approach in a small, non-complex plane typically looks like this:

Enter the pattern in the downwind leg. Slow down and start setting flaps. Turn on carburetor heat, double-check traffic situation and turn into base (90 degrees off the landing direction).

Double-check the location of the runway, check wind, possibly check landing lights. Start loosing altitude, typically about 200 feet. Now you are ready for the final approach.

Turn one more 90 degree turn into final. The runway is in front of you now. Make sure not to loose too much speed and/or altitude during the turn. Check and adjust the glide path, align the aircraft with the center line of the runway.

As the wind is almost never coming from straight ahead, I usually drift away from the center line.

Cross or crab?

There are two possible ways to compensate for that. I can turn the nose into the wind and approach the runway at an angle. In this scenario I have to straighten the aircraft out shortly before I touch down. If I don’t do that, the landing gear gets pushed down the runway sideways and may break. The crabbed approach is how the big airliners do it.

My flight school prefers to teach the other method, however. In this I use the ailerons to lower the wing into the wind. So if the wind comes from the right, I lower the right wing tip. If I would only do that, the aircraft would start a right turn. To counter act that, I push the left rudder pedal which forces the nose to the left and counter acts the movement to the right.

Now I have to hold the balance of these counter acting steering impulses. As drag increases from the crossing of the rudders, I have to make sure we don’t get too slow. For this I keep the nose down a bit. Also I have to make sure we get to the touch down zone of the runway and I have to adjust the power setting of the engine accordingly. Sounds complicated? It is!

So why do I learn this complicated method as opposed to the straight forward angle of attack? Well, the significant advantage is that I am already aligned with the runway in the very last moment of the approach when I flare the aircraft out. I can concentrate on slowly reducing the energy of the movement of the plane before it touches down hopefully very softly. The aircraft can easily touch down on one wheel first and the settle down on the other one as the lift reduces and the aircraft “gets heavier”.

How high is a beer bottle?

If I would hold the attitude of the aircraft until it makes contact with the runway, the nose wheel would probably be the first thing to touch down. It would probably collapse and the prop would strike the tarmac. A very expensive landing.

That is why I pull the nose of the aircraft up shortly before the landing. Now the aircraft is supposed to float down the runway with this nose-up attitude. The engine is in idle and the attitude means a lot of resistance. So the aircraft is supposed to slow down, the lift decreases and eventually the main wheels make contact with the runway, cat like.

My first flight instructor always told me to flare and float at about the distance of a beer bottle from the runway. It took me a long time to figure out how high a bottle of beer is…

To be continued…

 

(originally posted on January 25, 2013 by tilbo at aloft.blog.com/landing/)

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