Instrument approaches need some polishing...any advice?
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Instrument approaches need some polishing...any advice?
Hi,
I hope that this post is in the correct forum. I’m currently working on my instrument rating in a C172, and I’m afraid my technique needs a bit of polishing. Basically, my problem is that on instrument approaches (especially ILS) I tend to zig-zag around the localizer course. I never exceed 2 dots deflection, but I’d like to aim for no more than half dot or one dot deflection.
I presume my problem is that I’m over controlling because I’m trying to correct too aggressively, but my fear is that if I make my corrections too small, that I won’t have enough time to get ON the beam centerline. I don’t usually have any trouble until passing the OM, or maybe above 1000ft. I know the needles get more sensitive here, but are there any techniques that people use to get a smooth ride? I get very irritated with myself when I end up doing it, and my instructor reminds me that I’m still performing to standards, but I really think that even though I’m “good enough”, it’s still sloppy.
I’ve also occasionally noticed oscillation about the glideslope, but that tends to go along with the swimming around the localizer issue, so I take it that I’m probably putting so much work into the lateral path that I don’t pay enough attention to the vertical profile.
Are there any techniques anybody can suggest to smooth out my instrument approaches? Is it possible that I’m simply not scanning fast enough?
Thanks for any help I get
I hope that this post is in the correct forum. I’m currently working on my instrument rating in a C172, and I’m afraid my technique needs a bit of polishing. Basically, my problem is that on instrument approaches (especially ILS) I tend to zig-zag around the localizer course. I never exceed 2 dots deflection, but I’d like to aim for no more than half dot or one dot deflection.
I presume my problem is that I’m over controlling because I’m trying to correct too aggressively, but my fear is that if I make my corrections too small, that I won’t have enough time to get ON the beam centerline. I don’t usually have any trouble until passing the OM, or maybe above 1000ft. I know the needles get more sensitive here, but are there any techniques that people use to get a smooth ride? I get very irritated with myself when I end up doing it, and my instructor reminds me that I’m still performing to standards, but I really think that even though I’m “good enough”, it’s still sloppy.
I’ve also occasionally noticed oscillation about the glideslope, but that tends to go along with the swimming around the localizer issue, so I take it that I’m probably putting so much work into the lateral path that I don’t pay enough attention to the vertical profile.
Are there any techniques anybody can suggest to smooth out my instrument approaches? Is it possible that I’m simply not scanning fast enough?
Thanks for any help I get
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Try and calculate a rough wind direction and heading before you get established on finals. Then keep it smooth and relax. Dont over focus on one aspect of the approach, keep the scan going and look at the larger picture. Remember to change your heading as you descend to accomodate for the wind backing. That helped me when I did my IR.
Slow and steady needle movement is the trick. I have found most new IFR pilots over control because the want to fix the problem right away and put in too large corrections. One trick is if the LOC needle is out of the centre put in a correction and then as soon as the needle starts to move immediately take out half your correction. The needle should then just ease over. You should also work at having the aircraft properly trimmed. If you have a good trim the glideslope will take care of itself and you can concentrate on the loc.
The glideslope is a constant rate of descent roughly 5 x groundspeed, ie at 90 kts you are looking for 450 fpm, To adjust the heading use rudder for small corrections as adverse aileron yaw can negate use of ailerons. Lastly do not get fixated on the needles. concentrate on wings level, in balance and adjust RofD and headings to track it. Remember the small adjustments you make landing visually, then think about how they will look on an attitude indicator.... very small
Good luck
Good luck
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Sir,
As mentioned before try to figure out the wind direction on the final before leaving the initial approach altitude and remember that it usually backs as you descend. So if wind is from left you need to adjust heading to the left increasing the wind correction as you come down and if from right heading change is in the same direction and wind correction gets smaller as you descend.
Use GPS to get g/s and track information or DME for g/s.
If aiming for bigger A/C's forget about the using only rudder for corrections trick (in my opinion forget that anyways). Use ailerons and rudder to achieve balanced turns (adverse yaw will likely lead to too big corrections since you first start turning in wrong direction). No more than 5 degrees of bank and no more than 5 degrees of corrections in heading (usually only 1 or 2 degrees at one time is enough) will be needed once you've got the rough heading figured out. Wait for the change to happen and constantly think ahead -> what will happen if I maintain this heading.
Good trick is to maintain the heading within the heading bug width (if you've got one) and then correct the heading if corrections needed are clearly are out of that.
Always correct if you notice an error or tendency, even if it is as small as one quarter of a dot.
Safe flying,
Olabade
As mentioned before try to figure out the wind direction on the final before leaving the initial approach altitude and remember that it usually backs as you descend. So if wind is from left you need to adjust heading to the left increasing the wind correction as you come down and if from right heading change is in the same direction and wind correction gets smaller as you descend.
Use GPS to get g/s and track information or DME for g/s.
If aiming for bigger A/C's forget about the using only rudder for corrections trick (in my opinion forget that anyways). Use ailerons and rudder to achieve balanced turns (adverse yaw will likely lead to too big corrections since you first start turning in wrong direction). No more than 5 degrees of bank and no more than 5 degrees of corrections in heading (usually only 1 or 2 degrees at one time is enough) will be needed once you've got the rough heading figured out. Wait for the change to happen and constantly think ahead -> what will happen if I maintain this heading.
Good trick is to maintain the heading within the heading bug width (if you've got one) and then correct the heading if corrections needed are clearly are out of that.
Always correct if you notice an error or tendency, even if it is as small as one quarter of a dot.
Safe flying,
Olabade
You've more or less identified your problem & solution in your post. So don't be in such a rush to intercept! The faster the needles close the more likely it is that you'll shoot through to the other side.
Try using half or less of the heading adjustment you're currently using. The goal at first is to get the needle to stop deviating any further. Of course if you did nothing else then they'd start again as you got closer. Once stopped or nearly stopped adjust heading again to get a SLOW movement back to the centre. Try 5 or 10 deg or so outside the OM, half or quarter that when inside the OM.
For GS, use 5 x groundspeed = required ROD in ft/min as a target. Increase ROD slightly if high, reduce slightly if low. Like the LOC, the initial goal is to stop the deviation continuing then to close. Try a couple of hundred ft/min outside the OM, 50 or 100'/min inside.
You can even reduce the intercept rate as you get closer to centre to cause a gradual merge
Try using half or less of the heading adjustment you're currently using. The goal at first is to get the needle to stop deviating any further. Of course if you did nothing else then they'd start again as you got closer. Once stopped or nearly stopped adjust heading again to get a SLOW movement back to the centre. Try 5 or 10 deg or so outside the OM, half or quarter that when inside the OM.
For GS, use 5 x groundspeed = required ROD in ft/min as a target. Increase ROD slightly if high, reduce slightly if low. Like the LOC, the initial goal is to stop the deviation continuing then to close. Try a couple of hundred ft/min outside the OM, 50 or 100'/min inside.
You can even reduce the intercept rate as you get closer to centre to cause a gradual merge
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The glideslope is a constant rate of descent roughly 5 x groundspeed
I think one very important thing is to find out the wind correction you need BEFORE or AS SOON AS u start the APP,then it will be easier to stabilize your path.
just use gentle rudder corrections to keep the LOC and throttle+stick for the glide,and be gentle,don't overreact.
One good thing also is to be "stable" when starting the procedure,otherwise you might end up rushing things and exaggerating.
ciao
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Forget 5 x groundspeed, use ½ your groundspeed, it's easier to calculate under pressure and it's identical to 5 x your groundspeed.
i.e.
GS = 90kts, ROD = 5 x 90 = 450fpm.
or
GS = 90kts, ½ GS = 45 (or 450fpm.)
As has already been said the key to the LLZ is small movements and wait for the change. If you have a heading bug try and centre the heading bug and don't make any corrections outside the heading bug. That way your corrections will be small.
EDITED: Sorry, just seen the same advice given, should learn to read a bit more
i.e.
GS = 90kts, ROD = 5 x 90 = 450fpm.
or
GS = 90kts, ½ GS = 45 (or 450fpm.)
As has already been said the key to the LLZ is small movements and wait for the change. If you have a heading bug try and centre the heading bug and don't make any corrections outside the heading bug. That way your corrections will be small.
EDITED: Sorry, just seen the same advice given, should learn to read a bit more
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Command Heading
Check Airman:
From take-off to landing you should have a command heading in your mind for the stage of flight that you are doing.
On an ILS you have printed, the heading for a nil wind situation, use that heading initially and fly it exactly, if the localiser needle starts to move one way or the other, then change the heading a degree or so, wait and see and adjust again if neccessary ( a little more if the crosswind is strong) and remember the new Command Heading ! You will be amazed at the result of better track keeping.
The ability to fly a constant heading is the basis of success to any flying career.
Tmb
From take-off to landing you should have a command heading in your mind for the stage of flight that you are doing.
On an ILS you have printed, the heading for a nil wind situation, use that heading initially and fly it exactly, if the localiser needle starts to move one way or the other, then change the heading a degree or so, wait and see and adjust again if neccessary ( a little more if the crosswind is strong) and remember the new Command Heading ! You will be amazed at the result of better track keeping.
The ability to fly a constant heading is the basis of success to any flying career.
Tmb
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Thanks for all the advice so far. I notice that many people have said to try small (~2 degree) corrections. This seems like a great idea, and I tried it, but when flying an airplane of 1970’s vintage, I find it a little difficult to make that small of a correction. The dial is only marked every 5 degrees, and getting bounced around due to unstable air doesn’t help. I guess it’s the sort of thing that comes with experience.
Like I said, outside the OM, I’m usually ok, but it starts to turn south somewhere in the next mile. I really like the idea of halving the correction when the needle starts to move. I’ll have another go tomorrow, and hopefully I’ll get to try all these techniques.
Thanks again, and keep the advice flowing if you superior airmen remember anything more.
Like I said, outside the OM, I’m usually ok, but it starts to turn south somewhere in the next mile. I really like the idea of halving the correction when the needle starts to move. I’ll have another go tomorrow, and hopefully I’ll get to try all these techniques.
Thanks again, and keep the advice flowing if you superior airmen remember anything more.
You can still judge heading to within a degree or two. Is the lubber line exactly over the degree mark? A line's width the left or right? Halfway between two marks? Approximately halfway but slightly closer to one mark or another?
Each of those questions resolves the 5 degree markings into approximately 1 degree discernable change.
Turbulence is the norm, not the exception so like you wrote: You get used to it. It does make discerning a small heading change more difficult. You can still manage though by trying to pick the average of what heading is shown. Make small heading adjustments without particularly trying to fly to the desired heading only a couple or few degrees away.
Instead, roll to small angle of bank eg 5, 10 or 15 degrees, using coordinated controls then immediately back to wings level. Don't try to hold the AoB, just see it on the AH then roll upright again.
Each of those questions resolves the 5 degree markings into approximately 1 degree discernable change.
Turbulence is the norm, not the exception so like you wrote: You get used to it. It does make discerning a small heading change more difficult. You can still manage though by trying to pick the average of what heading is shown. Make small heading adjustments without particularly trying to fly to the desired heading only a couple or few degrees away.
Instead, roll to small angle of bank eg 5, 10 or 15 degrees, using coordinated controls then immediately back to wings level. Don't try to hold the AoB, just see it on the AH then roll upright again.
