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ILS approach

dspender

Well Known Member
Looking for guidance for the ILS approach. What speed are you at when at FAF? When do you drop flaps? Do you use 15% at FAF? What is speed down the GS? Do you use full flaps when the landing environment is captured?
 
I get slowed to 80 KIAS with half flaps prior to the FAF and fly final at the same speed/config. Takes around 15 inches MP in level flight and 10 inches on the descent. Could fly faster if needed, but slowing for landing takes time and distance. I typically roll flaps full and slow once below the weather.

Dave
N102FM
 
Here is a chart I put together. Numbers are about right. Getting slow enough for full flaps is always the challenge.

Carl

N7ZK Power/Speed Configuration Setting
September 9, 2015

MP RPM IAS VS
Climb 24 2400 130 1100

Low IFR Cruise 20 2200 150 ----

Cruise Dec 15 2300 130 -500
18 2350 170 -500

Appr Level 16 2200 100 ----

Prec Appr Dec 14 2200 85 -300

N-Pres Appr Dec 12 2200 85 -700
 
I generally shoot for 90 KIAS at the IAF regardless of the approach type and select first notch of flaps (zero deg on my plane) and maintain that speed and config throughout the approach all the way to the MAP. I prefer not to use any more flaps than that until landing is assured. I have no problem flying it faster than 90 if ATC requests it, but my preference is to keep it on the slow end -- more time to react.
 
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Personally, I htink 80 knots in actual IMC in the 10 is a little low. Just my opinion. :)

I fly all holding procedures at 18" of MAP which gives about 120 KIAS. The autopilot is comfortable there, and I think ATC appreciates the speed. Usually when it's IMC there are other airplanes around and sequencing is easier at these speeds.

Crossing the FAF I will bring the flaps out of reflex, and slow to 105-110. I do NOT add any more flaps unless I break out visually and am assured the runway is in sight and I can execute a normal landing. Even with a breakout at minimums, with 110 KIAS and flaps out of reflex, the 10 will have no problem slowing to final flap speed and making a normal landing, without using excessive amounts of runway.

On the other hand. If you have the flaps hanging out and execute a go around in IMC without being prepared for the pitchup that the 10 will give you, you are going to have your hands full at the most inopportune time.

I like very small changes when in actual IMC. :)

Vic
 
I've been dropping to 15 degree flaps at FAF, and intercepting glideslope at about the same time, and then flying the GS at 90.

I think I might start trying what you guys are suggesting, and just flying the GS with 0, and kicking in more flaps if/when you break out. My CFII always tried to get me to wait for a few seconds after going full throttle during a missed before I raised the flaps, but if I waited that long, I'd overspeed the flaps very quickly. Now for a missed, I hit go full throttle, pull up, hit toga, and flaps to 0 all about the same time.
 
I've been flying approaches very similar to Vic. My last ILS was into Dulles, so there was plenty of runway if I landed a little hot.
 
+2 for Vic's settings. I usually slow to 150kts when I'm getting close to the turn to final, then when I'm established I'll bring the flaps out of reflex. 90kts is the slowest I want to fly the GS, so I will be between there and 120kts depending.

Sometimes approach wants me to keep the speed up and other times they ask that I slow down for spacing. When I have the runway in sight prior to reaching minimums I'll slow down to 85 to get the rest of the flaps out for landing.

~Marc
 
While I agree with Vic and Bob and fly my approaches at the higher airspeeds for comfort and ATC spacing, just be aware that if you're going to use Cat A minimums, they require 90 kts or less approach speed. I also agree that flaps should be lowered only when the field is in sight. I just flew my BFR/IPC ride on Friday and I had this discussion with the check airman who agreed wholeheartedly: about 100 kts on final, no flaps until the field is in sight at minimums. Plenty of time to slow down to flap speed. Field not in sight, just add power and go missed, flaps are already up.
 
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While I agree with Vic and Bob and fly my approaches at the higher airspeeds for comfort and ATC spacing, just be aware that if you're going to use Cat A minimums, they require 90 kts or less approach speed. I also agree that flaps should be lowered only when the field is in sight. I just flew my BFR/IPC ride on Friday and I had this discussion with the check airman who agreed wholeheartedly: about 100 kts on final, no flaps until the field is in sight at minimums. Plenty of time to slow down to flap speed. Field not in sight, just add power and go missed, flaps are already up.

The point that there maybe higher mins if you elect to fly at say Cat B speeds (91-120) is well taken. However, at the airports I frequent the CAT A and B mins tend to be the same (except sometimes for circling mins) regardless of the approach type. This might be atypical but seems to be the norm here in the mid-Atlantic and in the Southeast. Doesn't mean I don't check it when I self-brief the approach though.
 
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Yes, I forgot to mention the CAT A and B, but I do check them on the approaches and haven't found it be a problem yet.

Vic
 
In my RV7A, holding directions is easier at the higher speed so I have been using 110k for my approaches and slow down to about 90K as I get closer to DA or if I pop out of the cloud. As I slow down to 90, I drop my flaps to my first stop which is very little (maybe 10 degrees if memory serves me right)
 
Not a RV-10 but an RV. I am also with Vic. I don't like the sluggishness of slow speeds.
Very counter to what we were taught in the 172's. We were taught to pick a MP and RPM to establish 90kts for a nice stabilized approach.
I always feel a little guilty flying the gs @ about 110-120 but that is the most comfortable for me. Even breaking out at mins give plenty of time to get it down safely.
 
Personally, I htink 80 knots in actual IMC in the 10 is a little low. Just my opinion. :)

I like very small changes when in actual IMC. :)

Vic

Vic, I pretty much agree with you, with one exception: When the visibility is down to 1/2 mile at night. This means that at DA you see, a bit hazy, the approach lights and nothing else. No runway lights, no VASI. As far as I'm concerned this is IMC, right down to the ground. And, like you, I want only small changes in these conditions. So that means flaring at 100 kias and flaps in trail (okay for a very long runway), or pre-configuring much earlier. For these conditions I use half flaps and 80 (+5/-0) kias. Yes, that means more work on a miss. But the -10 climbs okay with half flaps, and the flaps retract slowly enough that you can react to the pitch changes.
 
Vic, I pretty much agree with you, with one exception: When the visibility is down to 1/2 mile at night. This means that at DA you see, a bit hazy, the approach lights and nothing else. No runway lights, no VASI. As far as I'm concerned this is IMC, right down to the ground. And, like you, I want only small changes in these conditions. So that means flaring at 100 kias and flaps in trail (okay for a very long runway), or pre-configuring much earlier. For these conditions I use half flaps and 80 (+5/-0) kias. Yes, that means more work on a miss. But the -10 climbs okay with half flaps, and the flaps retract slowly enough that you can react to the pitch changes.

I can't argue with you. However, I don't fly when it is 1/2 mi at night. :) At least I wouldn't plan on it.

Vic
 
My way to calculate approach speed...

Since I have an auto-pilot, I would likely use it for an ILS approach should the need arise.

Since I want to practice ILS approaches with and without the autopilot, it is easier to memorize just one or two sets of numbers that works for both methods.

Since my auto-pilot does not follow the glideslope automatically, I have to manually select the desired rate of descent once the slope is captured.

Since my VSP knob only has resolution in even 100s of FPM, I pick something reasonable such as 500 or 600 FPM.

Since the glideslope is typically 3 degrees (as far as I know) , a little math says 500/600 FPM is 94/113 Kt respectively. These are my target numbers for coming down the slope in the RV7A.

So far I've been practicing using the 600/113 numbers on the advice of my CFI but the 500/94 numbers may work out better since the speed is closer to (but still above) the max flap deployment speed.

NOTES:
1) Remember, in this case speed is GPS (over the ground) speed, to maintain 500 FPM at 3* slope. Wind will cause TAS to be something different.

2) Initially I have to dial in about 1000FPM descent to get the autopilot to react quick enough. then I back it off to 500/600 FPM.

My figuring anyway. If I'm wrong, I'm willing to stand corrected. YMMV

Bevan

Bevan
 
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Bevan,
Without having tried this, it looks to me like fine control to stay on GS will be hard. The only control you can vary is power. Also with a headwind you may end up with a fairly high airspeed, to keep your ground speed at the chosen number. Or with a good tailwind, end up close to stall speed. I wonder if you wouldn't be better off turning off the vertical autopilot mode. Then you can manually stay on GS with pitch trim and/or power changes.
 
I can't argue with you. However, I don't fly when it is 1/2 mi at night. :) At least I wouldn't plan on it.

Vic

There are certainly pros and cons, benefits and risks, to doing this. But as a cfii, if I'm going to sign a form saying a student meet the standards, I'd like to see them demonstrate that if at all possible.
 
Bevan,
Without having tried this, it looks to me like fine control to stay on GS will be hard. The only control you can vary is power. Also with a headwind you may end up with a fairly high airspeed, to keep your ground speed at the chosen number. Or with a good tailwind, end up close to stall speed. I wonder if you wouldn't be better off turning off the vertical autopilot mode. Then you can manually stay on GS with pitch trim and/or power changes.

I can Vary the rate of descent directly on the face of the AP and with power of course. The key is to maintain the ground speed close to 113kts while also maintaining an acceptable indicated airspeed for safe operation of course. So far 113 has been working out pretty good. Winds have been up to 15-20kts with the headwind component somewhat less. I suppose a calm wind day could better warrant the 94 number. 94 is 1.6 x stall while 113 is 1.9 on my airplane.

BTW, my autopilot is Trutrak digiflight IIVS.

I'm open to any other thoughts, suggestions and tips.

Bevan.
 
I can Vary the rate of descent directly on the face of the AP and with power of course.
Bevan.

Actually with the AP engaged in vertical descent mode power will not change the rate of descent. The AP will change the pitch as needed to keep it at the set rate. Adding power with the autopilot keeping the vertical rate fixed will result in increased airspeed, shallowing the descent angle so if low on the glide slope, adding power will result in you re-intercepting it. But it may be tricky to fine-tune. Yes, you can certainly change the AP (500, 400, 600 ft/min) to stair step down the GS.
Just watch out if you have a 30 knot tailwind. Then a 94 knot ground speed means 64 kias - pretty close to stall.
 
I also use 90-100 knots neutral flaps until the runway is in sight and then flaps as needed
if using the trutrak vision AP I prefer to ask for LPV approaches instead of ILS as the AP flys that great

Alan
N668G
 
I also use 90-100 knots neutral flaps until the runway is in sight and then flaps as needed
if using the trutrak vision AP I prefer to ask for LPV approaches instead of ILS as the AP flys that great

Alan
N668G

dito on this one. since upgrading to wass i have been amazed how well the AP flys the plane down to the runway.

i find faster is better than slower.
P1010409.jpg
 
ILS Approach

Great thread. My safety pilot and I had this same discussion the other day. I have been flying all my approaches at 90 kts with half flaps. It works ok, but frankly that is all I have tried and all I know. The negatives have been stated: sluggish A/P and busy missed approach. It does leave you in a good position to transition to land and keeps you in Cat A minimums.

I am going to try Vic's suggestion. It seems like a good compromise and I bet it takes fewer throttle adjustments to stay on speed. Go-around becomes a lot easier. My friend, who flies a 7, uses 120 kts and that surprised me. He says the 7 is much more stable at that speed and he has no difficulty slowing down.

I suspect that your personal decision has a lot to do with your A/P capability. If it tends to be squirrely then a higher approach speed may help. Flap management on the missed is the other major factor. I have a toggle on my stick grip and all I have to do is flip it. Pitch control and trim takes a lot of attention initially and I look forward to trying the missed without messing with flaps and trim so much. There are a lot of other things to attend to at that point in the missed.
 
To keep things really simple, I use 120 knots for everything in the approach environment.

16 inches produces 120 knots in level flight for maneuvering and holds.

10.5 inches produces 120 knots and a 600 fpm descent which closely matches the glide slope (no wind).

Full power produces 120 knots and a good rate of climb for the missed.

This way I only have to trim once, for 120 knots.

120 knots makes for easy math--two miles per minute (no wind).

Flaps up throughout obviously, unless I break out and am going to land.

Recently flew an ILS to minimums at SPI and had plenty of time to slow and lower flaps for landing once I broke out.

I have an O-360 with CS prop. RPM stays at 2400 all the time unless climbing on the missed.

LeRoy Johnston RV-6A Esperanza 1100 hours.
 
Actually with the AP engaged in vertical descent mode power will not change the rate of descent. The AP will change the pitch as needed to keep it at the set rate. Adding power with the autopilot keeping the vertical rate fixed will result in increased airspeed, shallowing the descent angle so if low on the glide slope, adding power will result in you re-intercepting it. But it may be tricky to fine-tune. Yes, you can certainly change the AP (500, 400, 600 ft/min) to stair step down the GS.
Just watch out if you have a 30 knot tailwind. Then a 94 knot ground speed means 64 kias - pretty close to stall.

Agreed and suggests staying with the 600 FPM 113Kt speeds. With the CS prop there is no difficulty in slowing down for flaps and making the landing once breaking out. If it becomes a missed approach, transition to climb and trim is also easy.

Bevan
 
I will try a faster speed (again) next time I'm out - and I honestly have never used the flaps = 0 position for anything other than a stop on the way down - wonder what i'm missing. Regardless of the speed you decide to fly at, if you're in level flight at that speed prior to the glide slope then 3 degrees nose low from that picture will maintain the glide slope; then it's just (groundspeed x 10)/2 for VSI (3 degrees) or ((groundspeed x 10)/2) - 100 for 2.5 degrees. I'm not sure that I think 80 KIAS with half flaps is too slow (it is slow) as it's almost 1.5 x stall speed.

==dave==
N102FM
 
Thank you for your replies. What I read most often is neutral flaps and constant airspeed, say 90- 100 or so kts somewhere between 15 to 18 mp. Flaps once the environment is in site. I plan to fly each approach as though I will go missed, yet hoping to so see the environment so I can safely land. Keeping the flaps neutral will lessen the workload if going missed.
 
Nice discussion. A strange glowing orb showed itself in the sky today, so I decided to head out and play with the constant 120 KIAS neutral flaps approach in my plane. 2000 RPM +- did the trick. Even with fixed pitch, I found myself able to slow enough at MAP's as low as 400' to easily set it down on a 3k' runway, a little more practice and I could probably get comfortable going to a 2k' runway. I like it.

And I really need to stop flying and travelling and re-do my panel, manual glideslope with the A/P knob was less than optimum. :eek:
 
I tried 115kts/0 flaps yesterday and it worked well.

For Dave, the 0 flap position is recommended for takeoff and climb. Raise to reflex position when at cruise altitude. Using 0 for the approach sets you up for the missed.

Also, if your climb and approach speeds are the same, then you don't have to mess with either flaps or trim on the missed - as pointed out earlier. I may try 120 kts as a compromise. My usual climb speed is 130 kts, in order to keep cylinder head temps below 400. 120 kts will work initially.
 
To keep things really simple, I use 120 knots for everything in the approach environment.

16 inches produces 120 knots in level flight for maneuvering and holds.

10.5 inches produces 120 knots and a 600 fpm descent which closely matches the glide slope (no wind).

Full power produces 120 knots and a good rate of climb for the missed.

This way I only have to trim once, for 120 knots.

120 knots makes for easy math--two miles per minute (no wind).

Flaps up throughout obviously, unless I break out and am going to land.

Recently flew an ILS to minimums at SPI and had plenty of time to slow and lower flaps for landing once I broke out.

I have an O-360 with CS prop. RPM stays at 2400 all the time unless climbing on the missed.

LeRoy Johnston RV-6A Esperanza 1100 hours.

I tried 115kts/0 flaps yesterday and it worked well.

For Dave, the 0 flap position is recommended for takeoff and climb. Raise to reflex position when at cruise altitude. Using 0 for the approach sets you up for the missed.

Also, if your climb and approach speeds are the same, then you don't have to mess with either flaps or trim on the missed - as pointed out earlier. I may try 120 kts as a compromise. My usual climb speed is 130 kts, in order to keep cylinder head temps below 400. 120 kts will work initially.
I'm in the Vic camp as far as speed goes. I fly very close to the RV6 above.

Once on the final course, I go to 2500rpm and leave it alone. I pick a speed that is never <100 knots and non-reflex flaps. Runway in sight, slow and flaps down. Miss - power up and pitch up, shouldn't require any trim change.

With the prop at low pitch/high rpm, reducing power really slows things down if needed for flap deployment. I find it very easy to slow, drop flaps and hit the touchdown target on most runways. I find 120 knots makes mixing it up with the jets at a Class B easiest... and the plane is groovy at that speed.

I takeoff with non-reflex or 1st notch on soft/rough field like my home field. All climbing and cruising in reflex.
 
In the FWIW column -

One of the reasons I haven't used the reflex position on approach is the speed limits I set on the flap switch; the other is ignorance (in a nice way). But I can cheat them down...

I tried the following experiment - fly at 300' at 105-110 KIAS, flaps 0 (1st notch), with the GPS on the TDZ for a distance reference; at 1 NM from the runway attempt to slow and configure with more/full flaps and make a normal landing. Repeat the experiment using 500' and 1.7 NM out to simulate a non-precision approach.

At 300' I was unable to slow down enough to make a normal landing on a 3,000 ft runway - I couldn't keep going down and slowing down at the same time. If the runway was longer and I didn't mind a longer touchdown, then it could be done.

At 500' there was still time/distance for me to slow in level flight to configure and then intercept a normal glidepath from above.

The choice/ability to do this really depends on the weather at the destination. It would seem though, that attempting to alter speed and configuration during the latter portion vs a stabilized approach could potentially lead to a higher probability of a poor or missed approach.

Anyway, next time you're out try it and see what you think.

==dave==
N102FM
 
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90knts and no flaps until field in sight for me in my 6A. I have overwhelmed my Trutrak pitch servo before when flying a coupled approach by dropping flaps. John
 
Personally, I htink 80 knots in actual IMC in the 10 is a little low. Just my opinion. :)

I fly all holding procedures at 18" of MAP which gives about 120 KIAS. The autopilot is comfortable there, and I think ATC appreciates the speed. Usually when it's IMC there are other airplanes around and sequencing is easier at these speeds.

Crossing the FAF I will bring the flaps out of reflex, and slow to 105-110. I do NOT add any more flaps unless I break out visually and am assured the runway is in sight and I can execute a normal landing. Even with a breakout at minimums, with 110 KIAS and flaps out of reflex, the 10 will have no problem slowing to final flap speed and making a normal landing, without using excessive amounts of runway.

On the other hand. If you have the flaps hanging out and execute a go around in IMC without being prepared for the pitchup that the 10 will give you, you are going to have your hands full at the most inopportune time.

I like very small changes when in actual IMC. :)

Vic

I find almost exactly the same procedures work great for me.
 
Personally, I htink 80 knots in actual IMC in the 10 is a little low. Just my opinion. :)

I fly all holding procedures at 18" of MAP which gives about 120 KIAS. The autopilot is comfortable there, and I think ATC appreciates the speed. Usually when it's IMC there are other airplanes around and sequencing is easier at these speeds.

Crossing the FAF I will bring the flaps out of reflex, and slow to 105-110. I do NOT add any more flaps unless I break out visually and am assured the runway is in sight and I can execute a normal landing. Even with a breakout at minimums, with 110 KIAS and flaps out of reflex, the 10 will have no problem slowing to final flap speed and making a normal landing, without using excessive amounts of runway.

On the other hand. If you have the flaps hanging out and execute a go around in IMC without being prepared for the pitchup that the 10 will give you, you are going to have your hands full at the most inopportune time.

I like very small changes when in actual IMC. :)

Vic

I'm the same way. No flaps except possibly out of reflex while in IMC.
 
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