ILS Approach and Landing Speeds

ajstoner21

ajstoner21

Cleared for Takeoff
Joined
Oct 31, 2010
Messages
1,344
Location
Fort Worth, TX
Display Name
Display name:
Andrew
Hey,
I have a question for all the experienced IFR pilots.

If you are flying an ILS at 90 knots, and don't break out until 200' AGL (whatever the minimum is), do you land (and float) at 90 knots? I would imagine not.

When on the approach do you try to slow to normal landing speeds and when you slow, is it difficult to maintain a steady glideslope? (70?)
 
ajstoner21 said:
Hey,
I have a question for all the experienced IFR pilots.

If you are flying an ILS at 90 knots, and don't break out until 200' AGL (whatever the minimum is), do you land (and float) at 90 knots? I would imagine not.

When on the approach do you try to slow to normal landing speeds and when you slow, is it difficult to maintain a steady glideslope? (70?)
Click to expand...

Not an "experienced" IFR pilot, but a newly-minted one.

The short answer is no, you do not slow down below your approach speed before you reach decision altitude on an ILS approach. Why? Because if you don't see the runway environment at that point in a precision approach, you immediately must execute a missed approach. You do NOT want to be slower at that point, because as it is, you will momentarily dip below DA as you power up, pitch up, and clean up the airplane.

On approach, you will probably have approach flaps out (when I fly an approach in a 172, I'm at 10 degrees of flaps and 80 kts.) So when you hit the DA and you have the runway environment in sight (see the regs for what constitutes the runway environment), you should have plenty of time to drop in the next notch or two of flaps, and have a normal approach to landing. Remember, on a precision approach, a normal glide slope will bring you right down to the 1,000 ft markers on the runway. That gives you plenty of time to slow down for a very normal landing. (It may be shallower than you are used to if you flew a normal traffic pattern, but that's normal.)
 
Thanks for you reply! That makes a lot of sense. I guess I forgot that 1000 foot marker detail.
 
ajstoner21 said:
Hey,
I have a question for all the experienced IFR pilots.

If you are flying an ILS at 90 knots, and don't break out until 200' AGL (whatever the minimum is), do you land (and float) at 90 knots? I would imagine not.

When on the approach do you try to slow to normal landing speeds and when you slow, is it difficult to maintain a steady glideslope? (70?)
Click to expand...

Standardize, practice, but remain flexible.
 
Last edited:
spiderweb said:
Richard Collins talks about a really fancy in-between version where he lowers gear and flaps at the FAP, and gradually reduces airspeed through the descent. I saw it on a Sportys video. It looked cool, but I don't like it. The reason is, it is hard enough to fly a really good ILS as it is without adding an extra item of difficulty to it.
Click to expand...

It also makes running a back-up timer for the approach a total guessing game, doesn't it?
 
denverpilot said:
It also makes running a back-up timer for the approach a total guessing game, doesn't it?
Click to expand...

That's a very good point, as well. Richard Collins' caveat was that if you do this, do it in your own airplane, with plenty of practice. I guess if you've been flying IFR for 10,000 years in the same airplane, you like to try new things?
 
jesse said:
You might just fly right past the runway if you do that.
Click to expand...

Good point. I should rephrase to, on an ILS, stay on the instruments until the DH. On an NPA, after leveling off at the minimum altitude, periodically look for the runway environment, staying on instruments if in IMC, and executing the missed at the MAP.
 
ajstoner21 said:
Hey,
I have a question for all the experienced IFR pilots.

If you are flying an ILS at 90 knots, and don't break out until 200' AGL (whatever the minimum is), do you land (and float) at 90 knots? I would imagine not.

When on the approach do you try to slow to normal landing speeds and when you slow, is it difficult to maintain a steady glideslope? (70?)
Click to expand...

Maintain 90 or whatever approach speed you use until either MAP/DH or when you break out. In most light airplanes, it does not take that long to slow down 90 kts to landing speed from 200' AGL.

If for some reason you are flying the approach into a very short field and you are concerned about slowing down sufficiently for a short field landing, then you may want to consider reducing your approach speed in that case.
 
spiderweb said:
Good point. I should rephrase to, on an ILS, stay on the instruments until the DH. On an NPA, after leveling off at the minimum altitude, periodically look for the runway environment, staying on instruments if in IMC, and executing the missed at the MAP.
Click to expand...
On the ILS I'll switch to visual if I'm clearly in visual conditions so that I can better configure the airplane to land and get a feel for the crosswind. Staying instrument only down to 200 ft doesn't give you much time.

Plus you're responsible for traffic separation once you get in VMC. It'd suck to prang into another airplane because you weren't looking.
 
jesse said:
It'd suck to prang into another airplane because you weren't looking.
Click to expand...

Especially while doing circuits. It could ruin the undercarriage! And then you have to land on the motorway and strike an articulated lorry! Then you'd be tossed out head first into the loo (or WC, if you're squeamish)!

You'd need a torch to find your way out!

150+Years+Since+London+Ben+Goes+Operation+6Mo4aqiTi-4l.jpg
 
jesse said:
On the ILS I'll switch to visual if I'm clearly in visual conditions so that I can better configure the airplane to land and get a feel for the crosswind. Staying instrument only down to 200 ft doesn't give you much time.

Plus you're responsible for traffic separation once you get in VMC. It'd suck to prang into another airplane because you weren't looking.
Click to expand...

That's why in the original, I said "if in IMC."
 
dmccormack said:
Especially while doing circuits. It could ruin the undercarriage! And then you have to land on the motorway and strike an articulated lorry! Then you'd be tossed out head first into the loo (or WC, if you're squeamish)!

You'd need a torch to find your way out!

150+Years+Since+London+Ben+Goes+Operation+6Mo4aqiTi-4l.jpg
Click to expand...

:goofy: :cornut:
 
In most of the light airplanes, slowing from the approach speed to landing speed in the last 200 feet (about 25 seconds at 500 FPM descent) isn't tricky, particularly as most ILS runways are comparatively long.

But it is helpful to have the skills to alter approach speeds as needed. When I was flying my speed-brake-equipped Mooney J I would routinely fly 160 to the IAF, cross the FAF at 130 (just below gear speed) and might maintain 130 all the way down - I could pop the brakes at DH, then add the flaps as I hit the appropriate speeds, and be below 80 crossing the numbers. But I "wore" that airplane - I flew it frequently and in IMC all the time. I wouldn't do it if I wasn't at the top of my IFR game or in a new-to-me airplane. Don't let anything pressure you into flying faster then you are comfortable going - it's YOUR approach from the moment you're cleared for it.

Someone mentioned timing the approach - which in my opinion has no value when flying an ILS. That topic's been hashed out in other threads on the board.
 
ajstoner21 said:
When on the approach do you try to slow to normal landing speeds
Click to expand...
Either about 400 AGL or when I have the runway environment in sight and have decided to land, whichever comes last.

and when you slow, is it difficult to maintain a steady glideslope?
Click to expand...
No harder than when you make your final configuration setting when you turn final in the VFR traffic pattern.

Also, I have some techniques I teach to make this easier, starting with making sure you're in the white arc from the FAF inbound with gear down and approach flaps set. If you're on an ILS (or already descending from a higher MDA) in that configuration, simply selecting full flaps and holding pitch attitude constant works quite well in most light planes. If you're on a nonprecision approach and level at MDA, reducing power from the approach-level power setting to your normal ILS descent power setting and selecting full flaps while pitching the nose three degrees lower than where it was in level flight at MDA also works well in most light planes.
 
nddons said:
The short answer is no, you do not slow down below your approach speed before you reach decision altitude on an ILS approach. Why? Because if you don't see the runway environment at that point in a precision approach, you immediately must execute a missed approach.
Click to expand...
If I have a good view of the runway environment before I reach DH on an ILS, I'm not going to delay configuring and slowing for landing down to 200 AGL, because I should be able to tell before then if I'm able to commit to landing. As mentioned above, I'll do that at 400 AGL if I'm sure I'll be able to land, just as I would in the VFR traffic pattern.

Why 400 AGL? Just trying to keep things as "normal" as possible, and obtain a good stable final visual segment on the approach so I can make a good "normal" landing at the bottom, because we do best that which we do most often, and I think most of us try to stablize speed and configuration for normal landings in the VFR pattern when we turn final about 400 feet and 3/4 mile from touchdown.
 
jesse said:
You won't know when you're in IMC if you stay on instruments and don't look out until DH.
Click to expand...

See my edited original post.

Of course you have to look out to see if you are in IMC. I'm not an idiot.

My point is that while in that literally grey area (say, near-zero visibility in the scud) where you may or may not see glimmers of things, pilots may be tempted to try to fly visually with high hopes that they're "just about" to see or get a clear shot at the runway environment. The instruments are there to help you fly in those conditions. Many authors have talked about this very important point of flying IFR. I guess they said it better than I have.

My main point with that element is: don't abandon instruments when they're keeping you flying well. I wasn't talking about breaking out at 1500 feet into beautiful visibility, people in the pattern, families picnicking, with bucolic stains of Beethoven's Pastorale Symphony in the background.

ANYWAY: the MAIN point of my original post was to be stabilized from the FAF, but that there's still time to change to final landing configuration before landing. Tim pointed that out better than I did.
 
jesse said:
On the ILS I'll switch to visual if I'm clearly in visual conditions so that I can better configure the airplane to land and get a feel for the crosswind. Staying instrument only down to 200 ft doesn't give you much time.

Plus you're responsible for traffic separation once you get in VMC. It'd suck to prang into another airplane because you weren't looking.
Click to expand...
Agree with what you said- but I generally had a feel for the crosswinds from my correction the keep the localizer centered. I never flew anything hotter than a 172 on an ILS so I always had time to slow it down. A faster plane- I can't say.

I always found it interesting to see "layers" of wind flying an ILS (or GPS approach) by the change in wind correction angle.
 
Ron Levy said:
If I have a good view of the runway environment before I reach DH on an ILS, I'm not going to delay configuring and slowing for landing down to 200 AGL, because I should be able to tell before then if I'm able to commit to landing. As mentioned above, I'll do that at 400 AGL if I'm sure I'll be able to land, just as I would in the VFR traffic pattern.

Why 400 AGL? Just trying to keep things as "normal" as possible, and obtain a good stable final visual segment on the approach so I can make a good "normal" landing at the bottom, because we do best that which we do most often, and I think most of us try to stablize speed and configuration for normal landings in the VFR pattern when we turn final about 400 feet and 3/4 mile from touchdown.
Click to expand...

I think you and my original CFII are the same person. Just about everything you advise is the same as he does!
 
spiderweb said:
See my edited original post.

Of course you have to look out to see if you are in IMC. I'm not an idiot.

My point is that while in that literally grey area (say, near-zero visibility in the scud) where you may or may not see glimmers of things, pilots may be tempted to try to fly visually with high hopes that they're "just about" to see or get a clear shot at the runway environment. The instruments are there to help you fly in those conditions. Many authors have talked about this very important point of flying IFR. I guess they said it better than I have.

My main point with that element is: don't abandon instruments when they're keeping you flying well. I wasn't talking about breaking out at 1500 feet into beautiful visibility, people in the pattern, families picnicking, with bucolic stains of Beethoven's Pastorale Symphony in the background.

ANYWAY: the MAIN point of my original post was to be stabilized from the FAF, but that there's still time to change to final landing configuration before landing. Tim pointed that out better than I did.
Click to expand...

Thank you! Means a lot coming from an instructor I respect.

sent from my android
 
Fearless Tower said:
There is this thing called peripheral vision.
Click to expand...
Which doesn't look straight ahead. All I'm saying is that looking up from your instruments to look at the situation isn't a terrible thing and can easily be done safely without completely abandoning them. Once it is clear that you can make the landing and IMC is not an issue there is no point to focus on the instrument when you can look at the big world outside.

If you break out at 500 feet there is no point in flying the instruments down to 200 ft. Instead you can look out the window and fly the glideslope. You'll end up in the same place and you can look for traffic, things on the runway, etc all at the same time.
 
Beyond the original question, the discussion has moved into one of the most important issues in Single Pilot IFR (SPIFR) operations -- the problem of shifting attention between the flight instruments and the view forward at the bottom of an instrument approach. This is solved in some high-end aircraft with Head-Up Displays (HUD's) which allow the pilot to have the flight instrument readouts projected into the forward view so the pilot can keep "flying the gauges" until reaching the MAP while simultaneously seeing if the runway environment appears. But what is the light plane pilot to do?

Part of the solution is preflight study. That means looking over the approach and sectional charts so you know what you are looking for (types of lighting, visual cues such as ground features, etc). Consider this another good reason for carrying sectionals even for IFR flying.

Another part is knowing the actual weather conditions (ceiling and visibilty) and how they relate to the HAT/HAA and how far from the runway you'll need to be in order to be able to make "a descent to a landing on the intended runway ... at a normal rate of descent using normal maneuvers." I want at least 1 mile of vis for every 400 feet I have to descent, and prefer 1 mile for every 300. So, if the vis is reported at 1 mile, and the MDA is 600 feet, I'm already on notice that I'm not likely to see the runway environment until pretty close in, and unless there is good approach lighting, I'll probably be pretty high (maybe too high) for a safe landing when I first see the runway.

Either way, if the vis is only one mile, there's not much point starting to look out forward until I'm within about two miles of the runway. Also, I'll add reported ceiling to field elevation, and that will let me know when I should expect to break out -- again, not much point spending some of my attention looking up forward until then unless my peripheral vision tells me I'm breaking out.

And one last thing is checking the heading indicator and the approach chart so you know which way to look for the runway. Say you've got a pretty good crosswind, so your heading heading on final for runway 24 (with a 238 final approach course) is 250. You'll need to look 12 degrees left (i.e., in the direction off the nose that 238 is from the top of the HI) in order to look straight at the runway. In low vis, given the very narrow field of view of your primary vision sensors, looking straight ahead instead of those 12 degrees to the left could be the difference between spotting the runway environment in time to land or not. Another concern is that even a "straight in" approach may be aimed up to 30 degrees off the runway centerline. And unless you've done some practice on this, you may be surprised how far to the side 10, 15, or more degrees really is.
 
jesse said:
Which doesn't look straight ahead. All I'm saying is that looking up from your instruments to look at the situation isn't a terrible thing and can easily be done safely without completely abandoning them. Once it is clear that you can make the landing and IMC is not an issue there is no point to focus on the instrument when you can look at the big world outside.

If you break out at 500 feet there is no point in flying the instruments down to 200 ft. Instead you can look out the window and fly the glideslope. You'll end up in the same place and you can look for traffic, things on the runway, etc all at the same time.
Click to expand...

I think we're overall in agreement on technique - I'm just saying that even staying focused on the gauges, with peripheral vision, I can usually tell when I'm starting to break out and when to start looking for the runway.
 
Thanks for this. There is a lot of good information here!

I was also thinking that the synthetic vision on the G1000 helps a lot with this issue, because even though it looks "cartoon-y," it is MUCH better than guessing what's below you. And, you get all that information while focusing on the instruments.

Ron Levy said:
Beyond the original question, the discussion has moved into one of the most important issues in Single Pilot IFR (SPIFR) operations -- the problem of shifting attention between the flight instruments and the view forward at the bottom of an instrument approach. This is solved in some high-end aircraft with Head-Up Displays (HUD's) which allow the pilot to have the flight instrument readouts projected into the forward view so the pilot can keep "flying the gauges" until reaching the MAP while simultaneously seeing if the runway environment appears. But what is the light plane pilot to do?

Part of the solution is preflight study. That means looking over the approach and sectional charts so you know what you are looking for (types of lighting, visual cues such as ground features, etc). Consider this another good reason for carrying sectionals even for IFR flying.

Another part is knowing the actual weather conditions (ceiling and visibilty) and how they relate to the HAT/HAA and how far from the runway you'll need to be in order to be able to make "a descent to a landing on the intended runway ... at a normal rate of descent using normal maneuvers." I want at least 1 mile of vis for every 400 feet I have to descent, and prefer 1 mile for every 300. So, if the vis is reported at 1 mile, and the MDA is 600 feet, I'm already on notice that I'm not likely to see the runway environment until pretty close in, and unless there is good approach lighting, I'll probably be pretty high (maybe too high) for a safe landing when I first see the runway.

Either way, if the vis is only one mile, there's not much point starting to look out forward until I'm within about two miles of the runway. Also, I'll add reported ceiling to field elevation, and that will let me know when I should expect to break out -- again, not much point spending some of my attention looking up forward until then unless my peripheral vision tells me I'm breaking out.

And one last thing is checking the heading indicator and the approach chart so you know which way to look for the runway. Say you've got a pretty good crosswind, so your heading heading on final for runway 24 (with a 238 final approach course) is 250. You'll need to look 12 degrees left (i.e., in the direction off the nose that 238 is from the top of the HI) in order to look straight at the runway. In low vis, given the very narrow field of view of your primary vision sensors, looking straight ahead instead of those 12 degrees to the left could be the difference between spotting the runway environment in time to land or not. Another concern is that even a "straight in" approach may be aimed up to 30 degrees off the runway centerline. And unless you've done some practice on this, you may be surprised how far to the side 10, 15, or more degrees really is.
Click to expand...
 
spiderweb said:
I was also thinking that the synthetic vision on the G1000 helps a lot with this issue, because even though it looks "cartoon-y," it is MUCH better than guessing what's below you. And, you get all that information while focusing on the instruments.
Click to expand...
It's a double-edged sword because it doesn't tell you when you'll be OK to look outside. That can tempt you to look too soon or too late, not to mention the temptation to continue below MDA/DH on the SVT when you can't see the real runway.
 
Folks, this has become way, way too complicated.

The windscreen becomes part of the scan once you reach some altitude where you expect to see the runway environment.

If I break out at 1000' AGL, I'm flying VFR to the runway.

If I'm at mins on an ILS from 500' AGL every 50 feet I make a glance out the windshield part of the scan.
 
dmccormack said:
Folks, this has become way, way too complicated.

The windscreen becomes part of the scan once you reach some altitude where you expect to see the runway environment.

If I break out at 1000' AGL, I'm flying VFR to the runway.

If I'm at mins on an ILS from 500' AGL every 50 feet I make a glance out the windshield part of the scan.
Click to expand...

:thumbsup:
 
Fearless Tower said:
I think we're overall in agreement on technique - I'm just saying that even staying focused on the gauges, with peripheral vision, I can usually tell when I'm starting to break out and when to start looking for the runway.
Click to expand...

The absolute worst case IME is flying an approach at night with low ragged ceilings vis at or near the mins and MALSR or equivalent. Under those conditions the wisps and tendrils at the cloud bases can really mess with your mental picture of the aircraft's attitude plus it's not unusual for the visual cues (runway & approach lights) to come and go as you drive along on the MDA. Whenever I encounter those conditions I keep my instrument scan going and just add the forward view into it until I'm in the flare.
 
gismo said:
The absolute worst case IME is flying an approach at night with low ragged ceilings vis at or near the mins and MALSR or equivalent. Under those conditions the wisps and tendrils at the cloud bases can really mess with your mental picture of the aircraft's attitude plus it's not unusual for the visual cues (runway & approach lights) to come and go as you drive along on the MDA. Whenever I encounter those conditions I keep my instrument scan going and just add the forward view into it until I'm in the flare.
Click to expand...

Good point - I deal almost eclusively with the SoCal marine layer, so with few exceptions, there isn't much in between when breaking out. you are eihter in the soup or you are out of it.
 
Ron Levy said:
It's a double-edged sword because it doesn't tell you when you'll be OK to look outside. That can tempt you to look too soon or too late, not to mention the temptation to continue below MDA/DH on the SVT when you can't see the real runway.
Click to expand...

I can completely see that being a big temptation.
 
You must log in or register to reply here.
Back
Top