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Stabilized IFR approach in a 6A

recapen

Well Known Member
I am currently working on my IFR rating in my 6A.
I have a 430W, SL-30, S-Tec-30 with standart steam guages.
IO360B1F6 with MTV12B CS prop.

Using approx 17"MAP and 2000RPM for 90 KIAS flying around.
My instructor wants minimum adjustments in the event of a go around so I've been trying Full rich with 2500RPM and 13"MAP (I think that's what I remember using) as I descend so that all I need is to add throttle if a missed approach is called for!

Anyone else flying final this way?
How are you doing it?
 
It?s certainly easier to fly an ILS if you avoid making large power or configuration changes as you get in close. So most cfii?s will recommend doing the landing check list some distance out - maybe the FAF, but no later than 1000? agl. This would include gas on fullest tank, fuel pump on, flaps in approach configuration, gear down, mixture and prop full in (except for high elevation airports). Now, for the airlines, ?stabilized approach? means no configuration changes right down to the flare. You can do that too, but it will require a long runway or a slower approach speed. Here?s what I do:(1) if visibility is reported as a mile or more (day)(2-3miles night), I?ll fly the approach around 100 kias. When/if field is in sight, reduce power add flaps, madly re-trim for 70 kias, land. (2) If visibility is 1/2 to 1 mile, then before reaching 1000? agl, I will have slowed to 75 kias with 20 deg of flaps, and have the plane trimmed to maintain the GS at that speed. Only minor adjustments until the flare. #2 looks like the airlines? version of a stabilized approach. Unfortunately it?s tough to practice - you have to find the right wx.
 
I am FP, so not sure this helps. I slow down to 90 or 100 Kts and add 10* of flaps at either the FAF or GS intercept. Rest of flaps go in after having the runway in sight (while it hasn't happened to me, I would slow down and add more flaps on the approach for a short runway at ILS minimums). With 6000 foot runways, I have no concerns being forced to land with just the 10* of flaps. For me, the RPM varies a bit based upon the wind. I work the throttle as I settle on the GS to get the speed I want for the conditions.

I don't fully understand the CFI's concerns. If you aren't capable of pushing in an extra knob without crashing at 200 AGL, I would not think you are prepared for the greater challenges of maintaining the LOC and GS on a windy and turbulent day. I find that much more difficult than pushing in a knob. For me anyways, pushing in the throttle is pretty much muscle memory and requires no thought or even looking at it. Prop should be the same.

When I was in primary training in the 172, I was taught to firewall both the carb heat and throttle with the same motion for a go around. Should be easy to to the same with the blue knob.

Larry
 
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I don't fully understand the CFI's concerns. If you aren't capable of pushing in an extra knob without crashing at 200 AGL, I would not think you are prepared for the greater challenges of maintaining the LOC and GS on a windy and turbulent day. I find that much more difficult than pushing in a knob. For me anyways, pushing in the throttle is pretty much muscle memory and requires no thought or even looking at it. Prop should be the same.

When I was in primary training in the 172, I was taught to firewall both the carb heat and throttle with the same motion for a go around. Should be easy to to the same with the blue knob.

Larry

I?ll bet that same cfi had you set the mixture full rich prior to landing. Why? In a go-around, it?s just one more knob to remember. The answer is, why make a stressful situation more difficult, when there is no harm in being prepared early?
 
I fly our RV9A very similarly in IFR. I try to set up the airplane in a way to make very few adjustments inside the FAF. In my airplane....
-17inches, 2300rpm, mixture LOP, and no flaps works well for maneuvering at 90kts.
-At the FAF (or glide slope intercept) dropping 10deg flaps and reduction to 12.5" sets up a perfect 500-600ft/min decent. (Doing this also allows pushing mix and prop all the way in during gumps without a prop surge).
-I do GUMPS checklist at the FAF and adjust nothing but throttle until the go around or the runway in sight.
-With runway in sight I will add additional flaps as needed. If IFR into a short field I will add 20deg flaps at FAF to minimize adjustments inside the FAF.

IFR flying in the RV is tons of fun! Good luck with your training.
-Tanner
 
I have been practicing a lot of approaches in my 6A as well. Mine is a fixed pitch prop, so the setup is easier for me, but I have found that I have a real hard time not getting too fast on the glide slope with only 10 degrees of flaps in. In order to stay on GS and 90 knots, I put in 20 degrees of flaps just before the faf or gs intercept. Anybody else have that issue?
 
Curious Latech15, which engine you running and what RPM's are working for you?

I have a 160hp 0-320 with a fixed Catto 3-blade so I'd like to borrow some of your settings.

Thanks!
 
I am currently working on my IFR rating in my 6A.
I have a 430W, SL-30, S-Tec-30 with standart steam guages.
IO360B1F6 with MTV12B CS prop.

Using approx 17"MAP and 2000RPM for 90 KIAS flying around.
My instructor wants minimum adjustments in the event of a go around so I've been trying Full rich with 2500RPM and 13"MAP (I think that's what I remember using) as I descend so that all I need is to add throttle if a missed approach is called for!

Anyone else flying final this way?
How are you doing it?

I completely agree with your instructor. A true IFR missed approach is a critical, high workload time, especially single pilot. You are close to the ground with zero visibility. Whatever you decide to do that works for you and your airplane, do it the same way every time regardless of the weather conditions.

Know the power settings for 300,400,500,600 fpm descents on approach, to adjust the GS for winds (even a tailwind, it could be a circling approach to the opposite runway). Set your prop rpm with the missed in mind, it doesn't have to be full power (flame suit on). My preference is at the FAF. Also know when to transition from approach to landing configuration. I like to keep my approach flap profile as consistent as possible so follow my standard pattern altitudes and flap configurations. I.E. 10/1000, 20/800, landing/runway insight. I don't want to be in a panic to suddenly slow to landing configuration when I pop out of IMC at 300 ft. I have never flown a slippery airplane, but I imagine it is 100x worse than the spam cans I fly.

Know the power configuration required to maintain level flight for each flap configuration. If you need to arrest your decent at any time you can apply this power level and know you will be maintaining approach speed (or close to it).

I have had the GPS loose signal just inside the FAF in IMC. It's not a time to be having extra items to "think" about.

Aviate, Navigate, Communicate

My 2c, for what it's worth.
IFR Certified: 12/2017, trained in C172 & Arrow
 
I fly our RV9A very similarly in IFR. I try to set up the airplane in a way to make very few adjustments inside the FAF. In my airplane....
-17inches, 2300rpm, mixture LOP, and no flaps works well for maneuvering at 90kts.
-At the FAF (or glide slope intercept) dropping 10deg flaps and reduction to 12.5" sets up a perfect 500-600ft/min decent. (Doing this also allows pushing mix and prop all the way in during gumps without a prop surge).
-I do GUMPS checklist at the FAF and adjust nothing but throttle until the go around or the runway in sight.
-With runway in sight I will add additional flaps as needed. If IFR into a short field I will add 20deg flaps at FAF to minimize adjustments inside the FAF.

IFR flying in the RV is tons of fun! Good luck with your training.
-Tanner

Pretty much exactly the same for me in my 9A. I drop 10 degrees of flaps at the FAF or just prior and it sets up nicely for the descent. Full disclosure - I'm not rated yet, my checkride has been moved twice in the last week due to really low weather, currently set for Tuesday next week.
 
I’ll bet that same cfi had you set the mixture full rich prior to landing. Why? In a go-around, it’s just one more knob to remember. The answer is, why make a stressful situation more difficult, when there is no harm in being prepared early?

That certainly makes sense. I was under the impression that going full prop was creating a challenge in getting the desired speed for the OP. If there is no down side, I agree fully with do it early. I have only limited experience with CS props, though I do recall being taught to go full prop in the pattern.

Larry
 
Pretty much exactly the same for me in my 9A. I drop 10 degrees of flaps at the FAF or just prior and it sets up nicely for the descent. Full disclosure - I'm not rated yet, my checkride has been moved twice in the last week due to really low weather, currently set for Tuesday next week.

In my fixed pitch 9A, I find I have trouble descending and slowing at the same time. The plane will do one or the other at a given moment, but not both. I'm currently exploring other methods for instrument approaches, but the one I've used the most is to set up full flaps and 70-75 kts prior to the FAF, and maintaining that configuration to minimums.

The 9A has a flaps deployment airspeed around 80 kts for anything over 10 degrees, so there's a fine line between enough drag to land after breaking out at minimums, and carrying all the drag you have throughout the whole descent. If you arrive at minimums with more than 80 kts IAS, the 9A seems to require a really long runway.

Very interested to see what other RV9 drivers do. I do agree with the OP's CFII that configuration changes inside of the FAF are best avoided if possible.
 
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I have been practicing a lot of approaches in my 6A as well. Mine is a fixed pitch prop, so the setup is easier for me, but I have found that I have a real hard time not getting too fast on the glide slope with only 10 degrees of flaps in. In order to stay on GS and 90 knots, I put in 20 degrees of flaps just before the faf or gs intercept. Anybody else have that issue?

That's interesting. My target RPM is 1500 for a 500 FPM descent and 90+ knots. I can do this with or without 10* of flaps, though I typically deploy 10* at GS intercept. The key is to slow down before starting the descent. If you start down at 120, you will have a hard time slowing down to 90. I usually pull the throttle to 1500 or less after the GS comes down about two or three dots from full deflection. By GS intercept I am at 90+ and drop the nose down and increase throttle to 1500 if I had dropped it lower to slow faster. At around 500' + from DA, I will pull back the throttle a bit to to get the speed down to 80-85 knots if I am above that, though I tend to naturally slow down a bit as I come down the GS. Once I am visual, I pull the nose up a bit to get my speed down to landing speed and add more flaps. At ILS minimums, I skip the extra flaps and just use extra runway (every ILS I have flown has been 5000'+ runways which is more than plenty for a no flap landing at 10 above landing speed, which I practice regularly). I feel it is safer to carry a bit of extra speed on a minimums approach. Better to land long, than get near stall speed in low vis conditions. I fly a 6, so can't comment on this method for a 9 which probably is less tolerant of extra speed.

I find that small throttle adjustments are typically necessary as I progress down the GS, likely due to changes in wind speed and/or direction.

The real challenge is when ATC asks for higher speeds. This requires time at level flight to bleed the speed, so I won't accept the request if ceilings are below 800 or so. That leaves me enough to bleed off the speed and then slip down to lose the altitude while visual.

I have a 320 with a Catto.

Larry
 
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Flight Path Angle/velocity vector

Not to make anyone a child of the magenta line, but a scan of your EFIS vector, VVI independant, will aid in close in stability while adding close-in drag from flattening CS props and adding flap.
 
Sorry, I don't fly approaches like that at all. I think your CFI is trying to prepare you for an airliner.

90kt is near the minimum sink speed for an RV, so very little power is required, meaning that if you get high it is really difficult to get down without speeding up. I fly faster, at least 100kt with 110 or 120 actually being better. Flying slightly faster makes it easier to be stable as more power is required, meaning you have more power to reduce to go down. There is no problem with slowing down to land, especially with a c/s prop. Most runways with an ILS are quite long. Breaking out at 300' will give you a mile to slow down to touch down speed. I aim for a 500' cloud base as my minimum.

I leave the flaps up until I can see something, another reason to fly fast. Most 2 seat RVs are speed unstable with the flaps down. That means it is difficult to trim out on the approach. Flying an approach with any flap makes the task much more difficult.

I would suggest to examine how your airplane works best, and not to operate how a trainee airline pilot in a PA-28 is taught. Fly at a reasonable speed with no flap.

Pete
 
Sorry, I don't fly approaches like that at all........I aim for a 500' cloud base as my minimum.
Pete

If you break out at 500? agl you can safely do just about anything. Here in the US ILS or LPV minimums are typically 200? and 1/2 mile vis. Breaking out at 200? at 120 knots, with a fixed pitch prop, just won?t work unless you have a 10,000? runway.
 
When I was at Boeing, I spent a full year doing research on unstable approaches. After I left, I published a short paper entitled "The Myth of the Unstable Approach," and you can find that easily enough on line. What got me started was looking at a half dozen ASRS reports of unstable approaches -- all landed just fine. And a half dozen ASRS reports of bad landings all came from, you guessed it, perfectly stable approaches.

The basic thesis was that the term "unstable approach" was a vague, unhelpful generalization that did nothing for accident investigation. Sure, it's good pilot technique, but at the time it was vastly overrated as a safety initiative. In fact, the Flight Safety Foundation finally came around and now talks about go around criteria separate from unstable approaches.

So on to RVs. First disclaimer - approaches are much easier to fly with a constant speed prop than with a fixed pitch prop, and it's easier to fly a precise approach by hand than with an autopilot. Why? With the autopilot handling the pitch, all you can do is chase airspeed.

Here's what I do in my fixed pitch RV-9A at an airport with significant regional jet traffic and Gulfstreams. I fly final on the ILS or LPV at 100 knots so that I can fit in better. At 500 feet, or sometimes lower, I pull the power all the way back and start adding flaps in passing 83 knots. It's not that big a deal!! Maybe it's a big deal in other planes, but it's not in the -9A. Try it both ways in the -6A and see what your plane does. Learn to fly your own plane, not somebody's idealization of how things should be done. And to be honest, I would not have found this technique if another CFII hadn't challenged me to see what my plane would actually do... Besides, if the runway has an instrument approach, it's probably not short. And if it is short, you probably don't need to worry about faster traffic behind.

One thing that I do not have down real well is a go around on autopilot. If I'm slowed down at 200 feet and hit TOGA and full throttle, the plane stays slow and it takes forever for the RPMs and power to build up. (You should not have this problem, I suspect). I may choose to reprogram the autopilot to pitch up to three or four degrees instead of the present five. Part of my solution is that I try not to fly IFR above an overcast that's lower than a thousand so that I have options in case the engine poops out. Following that logic, I'd never fly an approach to lower than 1000 feet. However, weather has been known to change, so regardless of what I anticipate, I need to know how to do a good go around at 200 feet.

When I had my old Cessna 175, 1" of manifold pressure was good for 100 feet per minute change, if I recall correctly, or 5 mph. Go find out what the numbers are for your 6A -- it makes small corrections much easier if you know about how much you need to correct.

So, yes, I agree with your CFII in theory, but not necessarily in practice. Pushing in a few more knobs is not that big a deal if there's good reason to have them set as something other than TOGA settings, like avoiding spark plug fouling. There's nothing time critical when you make the go around decision as the high workload comes later in the missed approach.

So go try things different ways. Find out what your airplane will and won't do, and what fits your personal style. See what you learn. You might get surprised, just like I still do.
 
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+1 for "The myth of the unstable approach"

Ed, I took from your paper that my focused involvement in the approach, landing and rollout - including knowing what I will do to go around or go missed - is at least as important as whether I'm flying an exact airspeed or descent rate or power/prop/mixture/flap setting.

Is that a fair interpretation of your paper?
 
+1 for "The myth of the unstable approach"

Ed, I took from your paper that my focused involvement in the approach, landing and rollout - including knowing what I will do to go around or go missed - is at least as important as whether I'm flying an exact airspeed or descent rate or power/prop/mixture/flap setting.

Is that a fair interpretation of your paper?

That's a bit of an oversimplification, but yes, basically. Glad you enjoyed the paper!
 
Did two approaches today -- an LPV with nobody following, and a high speed visual approach with jet traffic following, a super-busy approach controller, and an obvious rookie in the tower.

Flew most of the visual at 120 knots, and started slowing down at roughly 400 AGL with power all the way back. Didn't have to slip it, but then, the RV-9A doesn't slip nearly as well as other planes. Everything worked out just fine, hit my touchdown point on speed, and I demonstrated a very high degree of skill that I don't really possess. (I got lucky!)

So go try it and see what *your* airplane will do.
 
It’s not just about the airplane, basic trigonometry has a role to play. Assuming the glide slope for your “stabilized” approach is 3 degrees and your expected descent rate is 500fpm, your forward ground speed would have to be 94kts. Any more or less will change your rate of descent or your glide path. I would guess this would be good for relatively poor visual conditions in an RV. I’ve practiced with 600fpm descent and 113kts ground speed with good visibility and feel this would be better to fit in with other traffic and still be able to transition to landing configuration in time to make my touch down point.

I agree that ILS approaches are generally associated with runways that are long compared to the RVs requirements.

I practice 500 and 600fpm descent rates because I use the autopilot which only has settings for even 100 increments. YMMV

Bevan
Not instrument rated.
 
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So on to RVs. First disclaimer - ...., and it's easier to fly a precise approach by hand than with an autopilot.
.

Ed, I agree with most of what your wrote. However, for initial instrument students (the OP), I do think being unstabilized in the last 800 vertical feet makes life harder for them. Me too - I like to be in final configuration by 1000' agl if possible (for low wx approaches). But I do disagree with the above quote. Simply because my autopilot coupled approaches border on perfect. That's just a reflection on today's equipment, not me. I have a Trio Pro with auto trim usually driven by the GRT HX's commands, but I imagine other autopilots are equally good these days. I cannot hand fly as well as these boxes do. (If I use the FD (sort of cheating) I can come close.). There's little hunting for airspeed. Increase the throttle, it goes faster but quickly stabilizes, and vice versa. It's kind of embarrassing how good these boxes are, compared to me. BTW, I haven't noticed any issues on selecting missed approach. But the -10 has a lot of power, so quickly accelerates (if needed) and climbs. Assuming I haven't fallen asleep and forgotten to add throttle.
 
I have had my Rv-6 for three months. My instrument ticket for about 6 and I got it in a pa-28 so a few of these comments are really resonating with me. I plan on doing some more practicing this weekend so I?d like to clarify a few things. Do those of you who are flying the approach at 100 with no flaps, you are simulating breaking out of the clouds at 500 or so and just leveling off to reduce speed and then throwing the flaps in and descending at that point ? I will agree that I like the way the plane handles at 100 way better than 85-90, I have just had tomrouble staying that slow and on glide slope. If you are disregarding the glide slope at 500 or so then that is something worth trying.
 
Simply because my autopilot coupled approaches border on perfect. That's just a reflection on today's equipment, not me.

I should have been more specific, and you caught me! :) In calm air, all is fine and as it should be. But, toss in some thermals and downdrafts and things change drastically -- instead of having a feel in your hand for what pitch corrections are required, the autopilot does all that and all you've got is the airspeed indicator. And with no cues, all you can do is chase the airspeed like a pre-solo student.

Also, on the last 800 feet, if you're decelerating, it's pretty easy to follow glideslope with the elevator and watch the speed bleed off.

Your mileage may vary, and that's okay! Thanks for your post.

Ed
 
I have had my Rv-6 for three months. My instrument ticket for about 6 and I got it in a pa-28 so a few of these comments are really resonating with me. I plan on doing some more practicing this weekend so I’d like to clarify a few things. Do those of you who are flying the approach at 100 with no flaps, you are simulating breaking out of the clouds at 500 or so and just leveling off to reduce speed and then throwing the flaps in and descending at that point ? I will agree that I like the way the plane handles at 100 way better than 85-90, I have just had tomrouble staying that slow and on glide slope. If you are disregarding the glide slope at 500 or so then that is something worth trying.

Once I break out of the clouds, I no longer follow the GS (assuming I have good visual contact with the runway). If I am doing 90+ knots, I will usually level off for a bit to slow down and add more flaps. This better suits my normal landing profile, which is steeper than 3*. I find that the 6 doesn't want to easily loose speed down hill greater than 90+. Once down to 75 or 80 it seems far more willing to give up airspeed in a 500 FPM descent.

With an ILS to minimums, I slow down a bit on the GS and don't do anything while visual. Just too much effort finding the runway in those conditions. I don't seem to have any problems flying the approach at 85 knots. I still usually have time to get more flaps in and slow down, but know that I will be ok if hot and no flaps, assuming an appropriately sized runway, of course. Breaking out a minimums with low vis seems to require much more mental effort and theefore not as comfortable doing the things I do in good visual conditions with 500' However, in my approach prep, I would have confirmed that the runway length was enough to handle 90 knots and 10* of flaps. We have some nasty cross winds (rotors mostly - so windsock fully extended one second, limp the next) at my home airport, so I have a good idea what I need when carrying an extra 10-15 knots over the fence.

Larry
 
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If you break out at 500? agl you can safely do just about anything. Here in the US ILS or LPV minimums are typically 200? and 1/2 mile vis. Breaking out at 200? at 120 knots, with a fixed pitch prop, just won?t work unless you have a 10,000? runway.

Most places have 200' limit on precision approaches :) There's always more than one way to do most things!

For my skills and my airplane I don't plan to go anywhere that is forecasting below 500', and I prefer 800. If the actual is below 500 I still use 110kt, shut the throttle when I see the runway and land. If I can't slow down I'm off to the alternate. I rarely fly ILS for real as most places I want to go don't have one. I've only flown LPVs in the US.

There are 2 issues, what is the best way to fly the approach in your airplane, and what can your airplane/equipment handle. In my airplane approaching at 110kt is best, once I see the runway, or the lights, I shut the throttle, keep descending and slow to 70kt, taking flap at 80kt and use power to land where I want. I had 8 years vfr flying in my 6 before I started flying approaches. It took me a while to learn to fly my 6 (what I considered to be) well, not sure how this approach technique would work shortly after I got the airplane.

The other issue is the accuracy of your equipment. ILS can be checked out on the ground, altimeters can't. The check carried out for an IFR cert doesn't check the airborne accuracy of your altimeter. The in flight accuracy is very dependent on your static system, including placement of your static ports (a topic that has been debated here often). My static system isn't bad, but I wouldn't descend to 200', even into a 10000 ft runway. I haven't done the work to figure out what my static error is at approach speed. So I use 500ft as my approach limit as that makes sure I have sufficient margin for altitude errors, means I have no problems slowing down and just makes my life easier. In reality if the clouds are below 1000 the needs to be a pressing reason to go to that airport.
Pete
 
In my fixed pitch 9A, I find I have trouble descending and slowing at the same time. The plane will do one or the other at a given moment, but not both. I'm currently exploring other methods for instrument approaches, but the one I've used the most is to set up full flaps and 70-75 kts prior to the FAF, and maintaining that configuration to minimums.

The 9A has a flaps deployment airspeed around 80 kts for anything over 10 degrees, so there's a fine line between enough drag to land after breaking out at minimums, and carrying all the drag you have throughout the whole descent. If you arrive at minimums with more than 80 kts IAS, the 9A seems to require a really long runway.

Very interested to see what other RV9 drivers do. I do agree with the OP's CFII that configuration changes inside of the FAF are best avoided if possible.

With a FP prop, I would agree with you. I have a C/S installed and the ability to deploy airbrakes below 10" of manifold pressure is really nice.
 
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