Adding flaps during the descent

[azure]

Bruce, I think I gave the wrong impression. I didn't mean it was an issue, just that it's not something I can forget about. I'm not worried about it in the least, EXCEPT that I don't want to have to fuss with a freaking Francis hood at 200 AGL.

Hopefully if I can show him that I can land safely after flying the ILS visually down to minimums, all will be well with the world.

Everskyward, the 20 seconds is 15 to slow down below the white arc (slow pressure so as not to balloon), then 3 to hold down the flaps lever until it reaches 10 degrees, and another 2 or so to push the nose down and start descending again.

Okay, I don't know exactly how it breaks down, but it's something like that.

 

[murphey]

Another option..find another student (doesn't matter what type) and go practice someplace quiet. If an IR student, then both of you can practice under the hood. If your other seat isn't at that point yet, you get to practice with your eyes open to get a better feel for what's going on without the stress of foggles. Or your instructor.

As for going below glideslope...it's not just a bad idea, there's a reason for that glideslope - it's to keep you out of trouble with obstructions and geology. I've got to agree with the others here that you need to find another CFII if this one advocates going below the GS. Dumb. Really dumb. Expect to find a CFIT accident with his name on it someday.

 

[ScottM]

Everskyward, the 20 seconds is 15 to slow down below the white arc (slow pressure so as not to balloon), then 3 to hold down the flaps lever until it reaches 10 degrees, and another 2 or so to push the nose down and start descending again.

Isn't VFE in the 172 110 knots for 10% of flaps and then 85 knots for full flaps? How fast are you going that it takes so long to slow down to 110 knots? I think white arc starts at 85knots, if I recall, but the POH mentions that you can use 10% of flaps at 110 or maybe it is 100 knots. Best to read the book.

 

[Ted]

Scott, shouldn't you be asleep?

 

[poadeleted20]

Isn't VFE in the 172 110 knots for 10% of flaps and then 85 knots for full flaps?

Not in the older models -- they have a 100 mph/87 knot limit for any application of flaps. The allowance of 10 flaps up to 110 knots came in later models. If you're doing 100 knots or so, it really does take what in that situation is a long time to slow below 87 to be able to get the flaps out. That's why I recommend doing that before the FAF and flying the approach at 80-85 with 10 flaps in one of those older 172's.

 

[midlifeflyer]

Everskyward, the 20 seconds is 15 to slow down below the white arc (slow pressure so as not to balloon), then 3 to hold down the flaps lever until it reaches 10 degrees, and another 2 or so to push the nose down and start descending again.

That could be a problem in and of itself: way too much analysis.

I've flown an ILS in a 172 at 120 kts and have had no trouble at all landing in the first third of the runway. I bet your analysis would say that I couldn't land on the runway at all.

I think the same thing may be coming through in the discussion about various configurations.

I'm 100% with Bruce. Pick a configuration and learn to fly it proficiently. Once you have, the small changes that need to be made to fly it differently will be seen as just that - small changes.

 

[RMCN172RG]

I'm going to interject another item for discussion. I pulled this out of IFR Magazine earlier this year.

Basically I was taught and I suppose most CFII's use the same technique to reconfigure for landing when the foggles come off. Ingraining the idea that once you break out and see the runway your back to VFR and need to reconfigure and land using your normal VFR landing technique.

The problem being that you wind up making sometimes drastic configuration changes. The recommendation was, and it works for me, to continue to fly the approach until you are over the threshold. This should put you at about 50 feet above the runway set to land in the next 1000 feet. Then cut the power level off and let the plane slow down and settle to the runway.

The transition is really very easy and smooth, touchdown speed is a little fast with only 10 degrees of flaps but nothing drastic. This avoids the put the flaps, pull power, hold for airspeed, don't get back up in the soup oh where did that runway go flurry of action on short final.

 

[TMetzinger]

I'm going to interject another item for discussion. I pulled this out of IFR Magazine earlier this year.

Basically I was taught and I suppose most CFII's use the same technique to reconfigure for landing when the foggles come off. Ingraining the idea that once you break out and see the runway your back to VFR and need to reconfigure and land using your normal VFR landing technique.

The problem being that you wind up making sometimes drastic configuration changes. The recommendation was, and it works for me, to continue to fly the approach until you are over the threshold. This should put you at about 50 feet above the runway set to land in the next 1000 feet. Then cut the power level off and let the plane slow down and settle to the runway.

The transition is really very easy and smooth, touchdown speed is a little fast with only 10 degrees of flaps but nothing drastic. This avoids the put the flaps, pull power, hold for airspeed, don't get back up in the soup oh where did that runway go flurry of action on short final.

Sounds reasonable - for a 172 on a dry runway of reasonable length. Alter the conditions, alter how you solve the problem.

 

[RMCN172RG]

Sounds reasonable - for a 172 on a dry runway of reasonable length. Alter the conditions, alter how you solve the problem.

That's every landing VFR or IFR. Fly the plan until something changes then adjust.

 

[ScottM]

Scott, shouldn't you be asleep?

Yes!.

 

[azure]

Isn't VFE in the 172 110 knots for 10% of flaps and then 85 knots for full flaps? How fast are you going that it takes so long to slow down to 110 knots? I think white arc starts at 85knots, if I recall, but the POH mentions that you can use 10% of flaps at 110 or maybe it is 100 knots. Best to read the book.

Not in that 172. Any flaps are prohibited above the white arc. I'm not sure when they started allowing 10 of flaps up to 110, but it wasn't allowed in the '78 N model I flew at 76G either. (Yes, I do read the book! )

Mark, ouch. I don't think that's a fair analogy either. I never said that no one could slow the plane down faster, just that I can't. Not when I'm trying to keep precise control of the airplane. To me, trying to do the flare/dump exactly 10 of flaps/unflare thing and keep the needles centered at the same time is like texting while driving on the freeway during rush hour.

Ray, do you mean flying the GS with 10 of flaps already configured, or after breaking out?

 

[poadeleted20]

To me, trying to do the flare/dump exactly 10 of flaps/unflare thing and keep the needles centered at the same time is like texting while driving on the freeway during rush hour.

Which is why I recommended what I did way back at the beginning -- slow to 85 knots and configure with 10 flaps outside the FAF, fly the GS at 80-85 knots with 10 flaps, and then add the rest when you have the runway in sight and commit to land. That concept has worked beautifully for my IR trainees for years.

 

[Everskyward]

Everskyward, the 20 seconds is 15 to slow down below the white arc (slow pressure so as not to balloon), then 3 to hold down the flaps lever until it reaches 10 degrees, and another 2 or so to push the nose down and start descending again.

You don't need to level off to slow down, just pull the power back. I know that is contrary to the pitch for airspeed, power for altitude concept but this is a case where that doesn't work very well. Then you should be able to extend the flaps and push the nose forward at the same time. When you are using a flap lever without detents just push down and count a predetermined number of seconds. You don't need to be so focused on the flap indicator and you don't need to be at precisely 10 degrees either. The flap indicator is probably not that accurate anyway if it's anything like the ones in the older Cessnas I flew. I know this seems like a lot of things to do at the same time which is why very few people here like your CFI's technique for people who are just learning.

 

[poadeleted20]

You don't need to level off to slow down, just pull the power back. I know that is contrary to the pitch for airspeed, power for altitude concept

Not really -- you just reduce to the approach descent power setting rather than the approach level power setting, and hold the nose up where it was so you decelerate while you configure. Of course, in a 172 starting at 100 knots and an 87-knot flap limit, the power's going to have to come way back to make this work, but it can be done, although it's not something I recommend doing while on the GS until you've got a pretty good level of proficiency on GS tracking while not playing with configuration.

 

[Everskyward]

Not really -- you just reduce to the approach descent power setting rather than the approach level power setting, and hold the nose up where it was so you decelerate while you configure.

That's the same thing, just another way of thinking about it in order to fit a certain concept.

 

[RMCN172RG]

Ray, do you mean flying the GS with 10 of flaps already configured, or after breaking out?

On approach prior to the FAF or GS intersection I configure my 172RG for 10 deg flaps, gear down, carb heat on, 90 knots, 2300 RPm with MP in the 16 to 19 in range.

Then to get my 500 FPM descent drop the MP to around 14-15 in.

When I break out, drop the MP to <12 in, slow the aircraft while maintaining 500 FPM until the flare, then depending on altitude, goto flaps 20 or 30 as required.

See attached chart the file is large

www.altcompenv.com/images/speedset172rg.jpg

 

[azure]

You don't need to level off to slow down, just pull the power back. I know that is contrary to the pitch for airspeed, power for altitude concept but this is a case where that doesn't work very well. Then you should be able to extend the flaps and push the nose forward at the same time. When you are using a flap lever without detents just push down and count a predetermined number of seconds. You don't need to be so focused on the flap indicator and you don't need to be at precisely 10 degrees either. The flap indicator is probably not that accurate anyway if it's anything like the ones in the older Cessnas I flew. I know this seems like a lot of things to do at the same time which is why very few people here like your CFI's technique for people who are just learning.

Yes I could stay on the GS with some practice by reducing power. But reducing power without back pressure will just make the nose pitch down, right? Greater rate of descent at (eventually) the same, trimmed airspeed. To prevent that, you still have to flare. Steady back pressure, keep the wings perfectly level, no tolerance for error. Squint at the ASI to make sure you're in the white arc, count 3.5 seconds on the flaps, unflare, add power again smoothly, no tolerance for error or by then you will be full scale deflection in maybe 5 seconds. It still seems like texting while driving to me. I could probably do it with practice, but is it worth the trouble to work on at this point? Will I ever be flying an ILS to a runway so short I can't do as Bruce suggests, cut power after breaking out dump at least 10 of flaps, slip it in if I have to and land?

 

[Everskyward]

I could probably do it with practice, but is it worth the trouble to work on at this point?

I don't think so and most people with the exception of your CFI don't think so either.

Will I ever be flying an ILS to a runway so short I can't do as Bruce suggests, cut power after breaking out dump at least 10 of flaps, slip it in if I have to and land?

Probably not. Most airports with that short a runway don't have an ILS. PS: That's a challenge for someone to find one and prove me wrong.

 

[azure]

On approach prior to the FAF or GS intersection I configure my 172RG for 10 deg flaps, gear down, carb heat on, 90 knots, 2300 RPm with MP in the 16 to 19 in range.

Then to get my 500 FPM descent drop the MP to around 14-15 in.

When I break out, drop the MP to <12 in, slow the aircraft while maintaining 500 FPM until the flare, then depending on altitude, goto flaps 20 or 30 as required.

See attached chart the file is large

www.altcompenv.com/images/speedset172rg.jpg

Ah! Totally different bird. A lot more like a 177RG, just a little slower.

In the Cardinal it was 10 of flaps at the IAF (or while being vectored), 21 in. for 100 knots level. At glideslope intercept, drop gear and ride it down, 95-100 kts on the descent. At break out, reduce power, add extra flaps as appropriate and land. I never had formal IR training in it but tried my friend's method enough times visually that I'm pretty sure I could learn it that way.

Thanks for sharing, it really shows that every airplane is different and you have to adjust your technique as needed.

 

[SkyHog]

I don't think so and most people with the exception of your CFI don't think so either.

Probably not. Most airports with that short a runway don't have an ILS. PS: That's a challenge for someone to find one and prove me wrong.

KMYF 28R has an ILS with a landing length of 3401'. I believe that is the shortest in the United States:

But I think the approach is no longer there, since I can't find the plate anymore. Used to be, at least.

 

[gismo]

I've been following this thread from the beginning and am still a bit confused as to the answers to Liz's query. It seems clear to me that:

1. Changing configuration (e.g. adding flaps) while following the glideslope in actual or simulated instrument conditions is at the very least an advanced (i.e. beyond that appropriate for an IR student) technique, and probably a bad idea under most circumstances.

2. In any 172 is should be easy to land on any runway served by an ILS approach from an ILS approach flown with flaps up at 90 KIAS or less (baring a strong tailwind) either without lowering flaps (my preference), or by lowering flaps once the flight has proceeded beyond the DH and is being flown by visual reference. This must certainly be true at any airport where a pilot might be compelled by ATC to fly a faster than normal approach due to jet traffic behind.

3. If there is no reason to fly faster than Vfe on an approach it is preferrable to slow to (or below) Vfe and extend flaps before commencing the final descent on an ILS.

 

[poadeleted20]

That's the same thing, just another way of thinking about it in order to fit a certain concept.

If we're looking at Dogan's Six Configurations concept, it fits perfectly -- we're just dropping one transition and going straight from cruise descent to approach descent without stopping at approach level. Explained that way, trainees who understand Dogan's system pick it up in a heartbeat.

 

[Everskyward]

I've been following this thread from the beginning and am still a bit confused as to the answers to Liz's query.

I think the thing is that Liz's instructor wants her to slow down and configure after she has already intercepted the glidelope. His technique has her starting out below the GS then getting above it then finally reintercepting it at some point. I think that's what I got out of her posts anyway. In my mind this is a crazy way to do things as your priority at that point should be to stay on the glideslope. That's a hard enough task without making configuration changes which have you intentionally zigzagging up and down through it. It is possible to stay on the glideslope while making configuration changes but it is much more difficult and not something that should be asked of someone who is just learning to do approaches.

 

[poadeleted20]

Yes I could stay on the GS with some practice by reducing power. But reducing power without back pressure will just make the nose pitch down, right? Greater rate of descent at (eventually) the same, trimmed airspeed. To prevent that, you still have to flare. Steady back pressure, keep the wings perfectly level, no tolerance for error. Squint at the ASI to make sure you're in the white arc, count 3.5 seconds on the flaps, unflare, add power again smoothly, no tolerance for error or by then you will be full scale deflection in maybe 5 seconds. It still seems like texting while driving to me. I could probably do it with practice, but is it worth the trouble to work on at this point?

No, it isn't.

Will I ever be flying an ILS to a runway so short I can't do as Bruce suggests, cut power after breaking out dump at least 10 of flaps, slip it in if I have to and land?

Probably not, but how many times have you practiced that maneuver just flying around the traffic pattern? If you aren't proficient at it there, you're not going to do it well at the end of an ILS. So, if you want to do that (fly the approach clean at 100 knots or so and then chop-and-drop at the threshold), practice it a bunch going round and round the local traffic pattern until can do it as easily as a "normal" landing approach. Then try it at the end of an ILS.

BTW, you also need to be thinking about nonprecision approaches, where you are flying level to the MAP, and may see the runway at 400-800 AGL only a mile from touchdown on a sub-3000-foot runway, maybe even a slick one. If you're not slowed and configured at that point, can slow and configure without going back up into the clouds and then get down and slow and landed and stopped? The day it happens for real isn't the day to find out whether you can or not. Again, a reason to be reasonably slow and configured when you spot the runway. Keep in mind that the Law of Exercise suggests if you use different procedures/techniques for precision and nonprecision approaches, you'll need a lot more practice to do both well.

 

[azure]

You're not confused at all, Lance.

The problem is the pesky Vfe is more like 85 knots, not 90 (I think it's 87 to be exact, but whatever). As a practical matter, once I add flaps, I don't want to intentionally go faster than 80 knots (it's not hard to accidentally exceed Vfe with flaps already extended). That's too slow for ATC at DET and PTK, and is marginal at FNT.

So the choices are, find a quiet field and fly the approach with flaps, fly it without flaps anywhere, or add flaps "during the descent". As you say, adding them along the way is probably a bad idea. So the argument is really between the other two options.

 

[ScottM]

Not in the older models -- they have a 100 mph/87 knot limit for any application of flaps. The allowance of 10 flaps up to 110 knots came in later models. If you're doing 100 knots or so, it really does take what in that situation is a long time to slow below 87 to be able to get the flaps out. That's why I recommend doing that before the FAF and flying the approach at 80-85 with 10 flaps in one of those older 172's.

Not in that 172. Any flaps are prohibited above the white arc. I'm not sure when they started allowing 10 of flaps up to 110, but it wasn't allowed in the '78 N model I flew at 76G either. (Yes, I do read the book! )

Mark, ouch. I don't think that's a fair analogy either. I never said that no one could slow the plane down faster, just that I can't. Not when I'm trying to keep precise control of the airplane. To me, trying to do the flare/dump exactly 10 of flaps/unflare thing and keep the needles centered at the same time is like texting while driving on the freeway during rush hour.

Ray, do you mean flying the GS with 10 of flaps already configured, or after breaking out?

FYI

The 1979 model "N" increased the flap extension speed for the first 10 degrees to 115 knots (213 km/h). Larger wing tanks increased the optional fuel to 66 US gallons (250 l).[5]

That looks like when the speed was increased for the 10% of flaps.

Doesn't really help Liz since she is in a '78 172N

 

[poadeleted20]

So the choices are, find a quiet field and fly the approach...

You just hit the big point -- get good at ILS's somewhere without that high-speed traffic before you try flying them at PTK and the like. Once you can do them well at 80-85 knots, then you can expand your envelope.

 

[Everskyward]

You just hit the big point -- get good at ILS's somewhere without that high-speed traffic before you try flying them at PTK and the like. Once you can do them well at 80-85 knots, then you can expand your envelope.

+1

The problem is the pesky Vfe is more like 85 knots, not 90 (I think it's 87 to be exact, but whatever). As a practical matter, once I add flaps, I don't want to intentionally go faster than 80 knots (it's not hard to accidentally exceed Vfe with flaps already extended). That's too slow for ATC at DET and PTK, and is marginal at FNT.

Has ATC told you that 80 knots is too slow or is it your CFI who has told you that 80 knots is too slow for ATC? Just for kicks I looked up the IFR traffic inbound to KDET. It's not like there have been so many arrivals in the past few days.

 

[RMCN172RG]

You just hit the big point -- get good at ILS's somewhere without that high-speed traffic before you try flying them at PTK and the like. Once you can do them well at 80-85 knots, then you can expand your envelope.

Come to PORT HURON the ILS 4 at KPHN works wonderfully and traffic is usually pretty light. Seifridge Approach is lighter on traffic than Detroit or Flint also.

Plus we have better scenery.

 

[poadeleted20]

Come to PORT HURON the ILS 4 at KPHN works wonderfully and traffic is usually pretty light. Seifridge Approach is lighter on traffic than Detroit or Flint also.

If you're up that way, Selfridge ANGB has ILS's both ways, and will probably be thrilled to have the traffic count. Just don't touch down on your low approach -- 6 inches clearance is enough, but don't touch down.

Conversation heard at Dover AFB:
Tower: "Cessna 123, it looked like you got pretty close to the runway on your last pass. If you touched down that would be a real bad thing."
Cessna 123: "No, sir, we definitely didn't touch down, and we won't do it again."

 

[gismo]

You're not confused at all, Lance.

The problem is the pesky Vfe is more like 85 knots, not 90 (I think it's 87 to be exact, but whatever). As a practical matter, once I add flaps, I don't want to intentionally go faster than 80 knots (it's not hard to accidentally exceed Vfe with flaps already extended). That's too slow for ATC at DET and PTK, and is marginal at FNT.

So the choices are, find a quiet field and fly the approach with flaps, fly it without flaps anywhere, or add flaps "during the descent". As you say, adding them along the way is probably a bad idea. So the argument is really between the other two options.

And given those two choices, I'd opt for the former unless you're already comfortable flying no flap approaches at a higher speed. Either choice will work but your progress may be slower using a faster speed as the corrections must be more timely and smaller.

As to the instructor who seems to be advocating an ill advised configuration change on the glideslope, I'd tell him that you sought the advice of a wide range of IR pilots and CFIIs and that virtually all of them recommended against that procedure, at least at this point in your training. If he insists that you go against said sage advice, you should strongly consider seeking a different instructor.

 

[azure]

And given those two choices, I'd opt for the former unless you're already comfortable flying no flap approaches at a higher speed. Either choice will work but your progress may be slower using a faster speed as the corrections must be more timely and smaller.

I was already somewhat comfortable no-flaps, that's why we decided to add configuring for landing, and that's when things fell apart for me.

My instructor holds to "faster is better".

As to the instructor who seems to be advocating an ill advised configuration change on the glideslope, I'd tell him that you sought the advice of a wide range of IR pilots and CFIIs and that virtually all of them recommended against that procedure, at least at this point in your training. If he insists that you go against said sage advice, you should strongly consider seeking a different instructor.

Virtually?? I don't think a single person here or on the Red Board is for going below the GS...

 

[azure]

You just hit the big point -- get good at ILS's somewhere without that high-speed traffic before you try flying them at PTK and the like. Once you can do them well at 80-85 knots, then you can expand your envelope.

But as you said, getting good at two different methods means a lot of practice with both. At PTK the slow method won't work at all, and a lot of the time it won't work at FNT either. So why switch methods midstream when I'm most of the way toward getting it the flaps-up way?

And I do take your point about making sure I'm comfortable with "chop and drop" before doing it for real. I'm sure my CFII won't let me give up on configuring during the descent unless I can demonstrate proficiency with the other method. I don't think it will be a problem though. I know that I can go from approach descent (90-95 kts) to 10* of flaps starting from 400 AGL without ballooning, and be stabilized again by 300 AGL. Why should it be any harder from 200 AGL? I wouldn't do it at VLL, but all the ILS runways around here are >= 5000 feet.

A nonprecision approach with a 400 AGL MDA in low weather to a wet 3000 foot runway will probably be beyond my personal minimums for a while. I'll definitely practice the ones around here though (typical MDAs 500-800 AGL and/or runways >=4000 feet).

 

[azure]

Has ATC told you that 80 knots is too slow or is it your CFI who has told you that 80 knots is too slow for ATC? Just for kicks I looked up the IFR traffic inbound to KDET. It's not like there have been so many arrivals in the past few days.

A little of both. We were last at DET over a week ago but they did break us off for a Citation behind us, and asked us to keep our speed up at least one other time.

Also, at FNT we were cleared to land on 27 and then told to go around for landing traffic on 18. It's pretty much all the towered airports around here, though PTK is definitely the busiest (second in Michigan only to DTW I think).

It's also that my instructor argues that the airplane is easier to control accurately at higher airspeeds. Based on my experience so far, I can't argue with that.

 

[azure]

If you're up that way, Selfridge ANGB has ILS's both ways, and will probably be thrilled to have the traffic count. Just don't touch down on your low approach -- 6 inches clearance is enough, but don't touch down.

Conversation heard at Dover AFB:
Tower: "Cessna 123, it looked like you got pretty close to the runway on your last pass. If you touched down that would be a real bad thing."
Cessna 123: "No, sir, we definitely didn't touch down, and we won't do it again."

Hmm... last I heard Selfridge was no longer allowing practice approaches. That was over 5 years ago though, things might have changed since then.

When I was flying out of 76G I got FF from them all the time, and never once heard them vectoring a GA aircraft to any of their approaches.

 

[RMCN172RG]

Hmm... last I heard Selfridge was no longer allowing practice approaches. That was over 5 years ago though, things might have changed since then.

When I was flying out of 76G I got FF from them all the time, and never once heard them vectoring a GA aircraft to any of their approaches.

I don't think they allow them. I have heard them advise aircraft not to fly over the airfield.

 

[azure]

Come to PORT HURON the ILS 4 at KPHN works wonderfully and traffic is usually pretty light. Seifridge Approach is lighter on traffic than Detroit or Flint also.

Plus we have better scenery.

I'm sure we'll do it at some point. Fortunately we have GPS so PHURN being out doesn't affect us. (or is it back up now?)

It would be a treat to go there, I know that one so well I don't even have to brief the approach. Sort of feels like cheating...

 

[RMCN172RG]

I'm sure we'll do it at some point. Fortunately we have GPS so PHURN being out doesn't affect us. (or is it back up now?)

It would be a treat to go there, I know that one so well I don't even have to brief the approach. Sort of feels like cheating...

I don't suspect the LOM will ever be back. If you don't have IFR GPS you'll be like me and need vectors. Selfridge of your CFII should be able to help you there.

 

[SkyHog]

I don't get how "practice approaches" are not allowed.

Are they saying you are not allowed to go missed? If not, then how can they disallow practice approaches?

 

[gismo]

It's also that my instructor argues that the airplane is easier to control accurately at higher airspeeds. Based on my experience so far, I can't argue with that.

I don't necessarily agree with that. It is true that the plane's response to the controls will be "crisper" and although that does make the plane feel more controllable the faster you go the faster things go awry.