Loss of Stability Near the Ground

RobertSubnet

RobertSubnet

Pre-takeoff checklist
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Feb 28, 2011
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Robert
Hello All.

Working on landings it seems that as I get near the ground (< 500') all of a sudden the plane goes from being nice and stable to losing stability. The plane yaws, rolls, etc. This in turn screws up my approach. What I am wondering is there some sort of ground effect coming in to play that I need to anticipate when on final? Or is the plane always rolling, yawing, etc., and it is only because we are near the ground that it is really noticeable?

Thanks.
 
Don't over correct. Remember as you get slower the less airflow there is over the wings and elevator so the controls are going to be a lot more sluggish. Make small corrections as you get slower and closer to the ground especially in ground effect.
 
Yeah, that happens, turbulence, wind swirling around, thermals, makes life more interesting, you'll learn to deal with it, in fact, after a while you probably won't notice most of it.
 
Reframe bro. It is you and not the plane. Most likely. Have your instructor fly a pattern when this is going on for you. That way you will get an idea what is weather induced and what is stressed student pilot induced. And be like water.
 
RobertSubnet said:
Hello All.

Working on landings it seems that as I get near the ground (< 500') all of a sudden the plane goes from being nice and stable to losing stability. The plane yaws, rolls, etc. This in turn screws up my approach. What I am wondering is there some sort of ground effect coming in to play that I need to anticipate when on final? Or is the plane always rolling, yawing, etc., and it is only because we are near the ground that it is really noticeable?

Thanks.
Click to expand...

It ain't " ground effects".. that high...:no:
 
Could be uneven heating low to the ground (thermals) or wind.
Not ground effect.

See if it happens at other airports. I know a couple fields that have a consistent little drop I feel near one end of the field where the ground changes form parking lot to trees prior to the runway.

Keep your airspeed on point and it isn't a biggie.
 
There can be low altitude runway turbulence. Even turbulence in the flare.
 
Practice slow flight; Play with and feel the sloppiness (mushy) controls?
Increase approach speed, within reason?

I am still a student, so someone should correct me or confirm.
 
Two potential issues, one or both may be in play. As you get closer to the ground you get mechanical turbulence in the air column, and the closer you get to the ground, the more nervous you get and you start over controlling. Turbulence actually need very little input much of the time as the plane will resettle on its own to a large degree.
 
Henning said:
Two potential issues, one or both may be in play. As you get closer to the ground you get mechanical turbulence in the air column, and the closer you get to the ground, the more nervous you get and you start over controlling. Turbulence actually need very little input much of the time as the plane will resettle on its own to a large degree.
Click to expand...


Great point.....

Don't over correct... The plane will seek level flight on it's own... Most of the time...:yikes:
 
Not sure what kind of environment/terrain you are flying around, but in places with big tall trees (or other vertical obstructions), as you descend below the treeline (where the runway area has been cleared), there is often a pretty pronounced wind shift if there were any noticeable winds aloft, and sometimes a "burble" effect as well owing to the wind pattern blowing over the tops of the trees and down. Maybe not your scenario at all, but something I have noticed a lot in such places.
 
Don't fight it and don't sweat it. None of it matters a bit until you are 3 feet over the runway and even then you can still just keep flying and go around. The sensations you get from pitching and yawing while spatially distanced from any stationary object leads you to believe there is instability but actually you are gracefully slicing through the turbulent air just like a boat on a river.
 
35 AoA said:
Not sure what kind of environment/terrain you are flying around, but in places with big tall trees (or other vertical obstructions), as you descend below the treeline (where the runway area has been cleared), there is often a pretty pronounced wind shift if there were any noticeable winds aloft, and sometimes a "burble" effect as well owing to the wind pattern blowing over the tops of the trees and down. Maybe not your scenario at all, but something I have noticed a lot in such places.
Click to expand...

There was one runway I used to use in Mississippi that was very tightly surrounded by tall dense pines. It was kinda neat in that no matter how strong the crosswind was at the top, it was nothing when you touched down. The place was so tight though that if it was strong and you were crabbing, you had to kick the crab angle out pretty quickly or you could get in a bind with the trees.
 
Henning said:
There was one runway I used to use in Mississippi that was very tightly surrounded by tall dense pines. It was kinda neat in that no matter how strong the crosswind was at the top, it was nothing when you touched down. The place was so tight though that if it was strong and you were crabbing, you had to kick the crab angle out pretty quickly or you could get in a bind with the trees.
Click to expand...

Yeah, MS is a pretty prime example of this.
 
I'd have to be there to know for sure which but one of two things could be at play, mechanical turbulence or over correcting.

My guess is you're over correcting. As you get close to the ground the perception is you're moving faster, despite actually being at your slowest flying speed. Since you feel like everything is going so fast you start making rapid and large inputs and the result is the plane bouncing around.

Solution? Stop doing that.

You fly the plane with pressures on the yoke, not movements of the yoke.
 
To add to what Captain/First Officer says.... DON'T LOOK AT THE GROUND. Look down the runway and try to maintain an even attitude as it sinks in.
 
The question I have is are you trimming for airspeed as you slow down in the pattern on final? If you don't keep up on the trim, it takes more muscle as you slow which impedes finesse and adds deviation.
 
My thought was getting too slow down low so the control surfaces are less effective.
 
AdamZ said:
My thought was getting too slow down low so the control surfaces are less effective.
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Not many students are guilty of getting too slow, unless their instructor is clueless, and makes them fly some crazy too fast speed (seems like the majority do).

Slower will make the airplane handle differently, as will the winds and whatnot rolling off surrounding structures/terrain, but slower is a necessary component to landing.

My best advice to the OP is:

Practice, practice, practice, do your best not to "fear" or "overthink" it. Just make the airplane do what you want. One day it just "clicks" for most students.

You won't likely have a breakthrough trying to really analyze it. You'll have a breakthrough as your experience and skill grow. You'll go from being all over the place to it looking like you're riding rails down the glideslope.
 
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