View Full Version : That TLAR doesn't look right
In the latest edition of Soaring magazine there is an article about TLAR. For those not familiar with TLAR, it is a landing approach teaching method that is based on angles as opposed to elevations and distances.
Using angles automatically compensates for variations in altitude. On downwind , if you are high, you fly further away from the runway, if you ar low you fly a shorter pattern. The TLAR method is superior and safer than trying to teach fixed distances and specific altitudes for turns.
However, I found a problem with something said in the article, but being the author a very recognized figure in the world of soaring, I was hesitant to write about it. I am refering to the dip angle between the glider and the runway on the downwind leg.
The article states "The pattern shpuld be flown so on the downwind leg, opposite the touchdown point, the pilot is about 600 feet above the ground looking down at the touchdown point at a 45 degree angle". That angle looks too high for me, and I think it could be dangerous.
I've always thought that angle should be more around 25 degrees, which would produce close to a 1-on-2 slope, as opposed to the 1-on-1 slope of 45 degrees.
The 25 degree angle will put you at around 1300 feet from the runway, or close to a quarter mile away when you are at 600 ft agl.
Getting too close to the runway prevents the pilot from having a good base leg where you can better judge your position to enter the very important base-to-final turn. In the worse case scenario, being too close will force you to use very steep banks or going for a button hook turn. New pilots and many old pilots may try to force the turn with rudder, and we all know how bad that can end.
Is 600 ft too close? I'd say it is. I'll use a typical example. In calm conditions, many gliders fly a pattern at 50 knots. In theory, the radius of a 45 degree bank turn flown at that speed is 220 ft. But that doesn't take into consideration that you start the turn from zero bank, bank to 45 degrees, stay in the bank and unbank back to zero, so at the end you have a spiral turn, followed by a circular turn, followed by another spiral. If we assume it takes 2 seconds to bank to 45 degrees, the net effect is that your turn has an equivalent radius of 310 feet. When I repeat the calculations with a 30 degree bank, the equivalent radius of the turn is 440 feet.
I am trying to spare you from the equations, but if you don't believe me, look at your flight traces in google earth, or just using google earth, measure the distance from the location of your downwind leg to the runway. On your home airport, you should have a good idea of more or less where that is.. I assure you that nobody is flying at 600 ft, it would scare you. Also, take a look at the angle to the runway when you are flying. Definitely not 45 degrees. Even on your chair as you read this look down to your left or right at 45 degrees and imagine the runway is at the floor.A little steep?
On Saturday, July 11, 2015 at 8:40:56 AM UTC-6, wrote:
> In the latest edition of Soaring magazine there is an article about TLAR. For those not familiar with TLAR, it is a landing approach teaching method that is based on angles as opposed to elevations and distances.
> Using angles automatically compensates for variations in altitude. On downwind , if you are high, you fly further away from the runway, if you ar low you fly a shorter pattern. The TLAR method is superior and safer than trying to teach fixed distances and specific altitudes for turns.
> However, I found a problem with something said in the article, but being the author a very recognized figure in the world of soaring, I was hesitant to write about it. I am refering to the dip angle between the glider and the runway on the downwind leg.
> The article states "The pattern shpuld be flown so on the downwind leg, opposite the touchdown point, the pilot is about 600 feet above the ground looking down at the touchdown point at a 45 degree angle". That angle looks too high for me, and I think it could be dangerous.
> I've always thought that angle should be more around 25 degrees, which would produce close to a 1-on-2 slope, as opposed to the 1-on-1 slope of 45 degrees.
> The 25 degree angle will put you at around 1300 feet from the runway, or close to a quarter mile away when you are at 600 ft agl.
> Getting too close to the runway prevents the pilot from having a good base leg where you can better judge your position to enter the very important base-to-final turn. In the worse case scenario, being too close will force you to use very steep banks or going for a button hook turn. New pilots and many old pilots may try to force the turn with rudder, and we all know how bad that can end.
> Is 600 ft too close? I'd say it is. I'll use a typical example. In calm conditions, many gliders fly a pattern at 50 knots. In theory, the radius of a 45 degree bank turn flown at that speed is 220 ft. But that doesn't take into consideration that you start the turn from zero bank, bank to 45 degrees, stay in the bank and unbank back to zero, so at the end you have a spiral turn, followed by a circular turn, followed by another spiral. If we assume it takes 2 seconds to bank to 45 degrees, the net effect is that your turn has an equivalent radius of 310 feet. When I repeat the calculations with a 30 degree bank, the equivalent radius of the turn is 440 feet.
> I am trying to spare you from the equations, but if you don't believe me, look at your flight traces in google earth, or just using google earth, measure the distance from the location of your downwind leg to the runway. On your home airport, you should have a good idea of more or less where that is. I assure you that nobody is flying at 600 ft, it would scare you. Also, take a look at the angle to the runway when you are flying. Definitely not 45 degrees. Even on your chair as you read this look down to your left or right at 45 degrees and imagine the runway is at the floor.A little steep?
A 45 degree "dip angle" (actually called "angle of depression") workes fine.. A number of off recent off field crashes could have been prevented had pilots been using this angle. It may look steep but it's safer to be high and close than far and low.
25 degrees of depression angle places the glider way too low and far from the runway to deal with unexpected sink.
I think the Soaring article is a good one.
Charlie M. (UH & 002 owner/pilot)
July 11th 15, 06:49 PM
Part of why 45* is discussed is that it is easy to reference within an aircraft.
Look at most of the round gauges with 4 screws "at the corners", a line drawn through the diagonal screws is 45*, thus easy to see.
Pattern should be taught, "Downwind track (meaning path over the ground, not fuselage alignment) parallel to the runway looking down at the runway ~45* angle.
Turn base when the touchdown point is ~45* behind you.
Turn final when you think it's time, allowing for wind drift.
Reference an aiming point (that is ~200' short of where you want to touchdown) on the canopy, adjust glide so the reference is stationary on the canopy using divebrakes and/or slips.
There will be adjustments in the pattern due to wind, lift & sink.
Why is this taught (assuming the instructor does any sort of cross country)? Because you have no real clue what the "off field elevation" is, so the altimeter is sorta dead weight.
Angles always work.
They work for a 2-33 (steep is fine) and 50:1 glass (a bit shallower is also fine).
But the angles work pretty much regardless PROVIDED your speed is reasonably close, you watch the angles (is it trending steady, getting steeper, getting shallower, etc.) and adjust as required.
I've been using the angles for decades.
I taught the angles (as a CFIG) for about a decade.
I've landed off airport more times than I want to admit. I have to yet overshoot or undershoot my predetermined landing spot by more than maybe 50'.
PS, "aiming spot" gives you a reference so you have a bit more time/distance to "flair to land".
I will have to reread the referenced article to see if I really see an error. I have seen a "power plane" diagram that basically showed that the "aiming spot" was where you were to land. Land hard maybe, but not at a minimum speed.
Dave Nadler
July 11th 15, 07:16 PM
On Saturday, July 11, 2015 at 10:40:56 AM UTC-4, wrote:
> ...A little steep?
Um, you might want to discuss this with the guy who crashed his V2 short of the ramp at Hobbs, from a 'routine landing pattern' during the nats...
Be safe out there,
Best Regards, Dave
I am not critisazing the method, as a matter of fact is the way I fly patterns. Except for the 45 degree dip angle. Did any one try to actually stand at a wall, put one foot in front of the other and move away five or six feet (not steps)? Now look at where the wall joins te floor and imagine there is a runway there. Did you try it using google earth?
I think the problem is that pilots see a dip angle of 30 degrees and think it looks like 45 degrees. Any skier will tell you stories of skiing down a wall when in reality de slope was well below 45 degrees.
So if you are teaching a student and you are at the right distance and angle, it doesn't matter what you call that angle, that is what is retained in his or her mind. So it looks about right, whether you call it 25, 30, 45, or 60 degrees. So i'm not worried about it. I am worried about someone actually trying to fly the downwind at 600 feet.
I talked to an instructor today that told me the same, he uses a 45 degree dip angle to the runway. Then he flew a couple of patterns at what I estimate was 1200 feet from the runway. I know because I measured 600 feet from the runway and nobody was even close to that line.
So the problem may be a matter of perception and calling 45 degrees what in reality is 30 degrees.
Tomorrow I will post what it is said on several books about distances and angles, including one by the author of the article.
I am not critisizing the method, as a matter of fact is the way I fly patte=
rns. Except for the 45 degree dip angle. Did any one try to actually stand=
at a wall, put one foot in front of the other and move away five or six fe=
et (not steps)? Now look at where the wall joins te floor and imagine there=
is a runway there. Did anyone checked google earth?
I think the problem is that pilots see a dip angle of 30 degrees and think =
it looks like 45 degrees. Any skier will tell you stories of skiing down a =
wall when in reality de slope was well below 45 degrees.
So if you are teaching a student and you are at the right distance and angl=
e, it doesn't matter what you call that angle, that is what is retained in =
his or her mind. So it looks about right, whether you call it 25, 30, 45, o=
r 60 degrees. I'm not worried about it. I am worried about someone actua=
lly trying to fly the downwind at 600 feet.
I talked to an instructor today that told me the same, he uses a 45 degree =
dip angle to the runway. Then he flew a couple of patterns at what I estima=
te was 1200 feet from the runway. I know because I measured 600 feet from t=
he runway and nobody was even close to that line.
So the problem may be a matter of perception and calling 45 degrees what in=
reality is 30 degrees.
Tomorrow I will post what it is said on several books about distances and a=
ngles, including one by the author of the article.
The primary problem with the article is it was written 40 years ago.
However, one of the major issues with typical landing patterns flown by many pilots is flying the downwind leg too close to the landing area (runway.)
(Watch what pilots are doing at your gliderport.)
This results in a too-short base leg. (Arguably, the most important of all the legs.)
A proper base leg allows safe adjustments to accommodate a reasonable glide slope on the final leg as well as avoiding the extremely dangerous, low altitude "buttonhook" base to final turn.
The 45 degree angle looking down at the runway while on the downwind leg is an angle easy to understand, teach and perform. The technique begins with a walk-through on the ground. The angles are easy to teach, understand, and perform.
Especially under the stress of an actual off-field landing.
It helps to prevent being too close to the landing surface while flying the downwind leg, is easy to teach and easy to perform.
Is a downwind leg better if flown at say 35 degrees? I suppose, however, the emphasis is not so much the angle but avoiding flying too close to the landing area so a proper length base leg is flown.
Gotta go to work now.
Tom Knauff
Dan Marotta
July 12th 15, 02:10 PM
I'm with you, Santirago.
I /_think_/ I fly downwind with about a 45 deg look down angle, but who
knows? I hold my head and eyes at about the same position as I look at
the runway while planning my final turn (180 deg descending turn to
final). It doesn't really matter what the angle actually is. It's
unfortunate to link TLAR (that looks about right) and a specific number
in the same article. Admittedly I haven't read the article yet. I'm
just commenting on what I've read here.
On 7/11/2015 7:22 PM, wrote:
> I am not critisizing the method, as a matter of fact is the way I fly patte=
> rns. Except for the 45 degree dip angle. Did any one try to actually stand=
> at a wall, put one foot in front of the other and move away five or six fe=
> et (not steps)? Now look at where the wall joins te floor and imagine there=
> is a runway there. Did anyone checked google earth?
> I think the problem is that pilots see a dip angle of 30 degrees and think =
> it looks like 45 degrees. Any skier will tell you stories of skiing down a =
> wall when in reality de slope was well below 45 degrees.
> So if you are teaching a student and you are at the right distance and angl=
> e, it doesn't matter what you call that angle, that is what is retained in =
> his or her mind. So it looks about right, whether you call it 25, 30, 45, o=
> r 60 degrees. I'm not worried about it. I am worried about someone actua=
> lly trying to fly the downwind at 600 feet.
> I talked to an instructor today that told me the same, he uses a 45 degree =
> dip angle to the runway. Then he flew a couple of patterns at what I estima=
> te was 1200 feet from the runway. I know because I measured 600 feet from t=
> he runway and nobody was even close to that line.
> So the problem may be a matter of perception and calling 45 degrees what in=
> reality is 30 degrees.
> Tomorrow I will post what it is said on several books about distances and a=
> ngles, including one by the author of the article.
--
Dan Marotta
Thanks for your replies.
Many may argue that it is safer to be closer to the runway than being far, and I think it is not true. By being too close to the runway there is no room for a proper base leg and you may have to do a 180 turn . If you start too high you risk overshooting the field, if too low there is the tendency to force the turn with rudder with the risk of a skidding turn at low speed and altitude.
I just want to quote Tom Knauff in his book After Solo:
"If you fly too close during the downwind leg, you will not be able to have a reasonable length base leg, and only have room for a 180 degree turn.The base leg is probably the most important of all the legs, when trying to make an accurate landing. A proper base leg will allow adjustments by using the spoilers and/or turning slightly away from or towards the field to help adjust for height. While flying on the downwind leg, keep a distance that allows you to be at least 45 degrees to the field, and better yet, 30 degrees. The important thing, is not the angle you are from the field, but the understanding that being too close makes it impossible to have a reasonable base leg."
Notice the "better yet, 30 degrees"
A 180 turn can definitely be performed within 600 feet, but then it has to be done quickly, with a good bank angle, and there is little room for adjustments in elevation. A safe 180 turn type of approach (naval aviator) requires (I think) bank angles that are less than 45 to have the room and time to adjust the rate of descent. In some way it is like having a curved base leg. But you may not do it safely if you are too close.
Please Dan correct me on this, I am not used to do the naval pattern.
As with most things, there are good reasons for the various techniques used in different environments. In the case of the Naval 180 degree turn to final, you must understand the environment the pilots are in.
They are landing on a boat in the middle of the ocean. There are no external references other than the boat. The boat is intentionally headed directly into the wind.
It is important to keep the only visual reference - the boat - in view as you fly the 'pattern.'
Thus the 180 degree turn method.
When landing in farmer Jones farm field, you will have lots of visual clues to use. To make the best use of these clues a disciplined rectangular flight path is an extremely effective method.
For those of you who are unfamiliar with the TLAR landing technique, and are motivated to fly safe, please read the latest edition of the "Glider Flight Training Manual." Available from the SSA or www.eglider.org
Tom Knauff
On Sunday, July 12, 2015 at 8:08:41 AM UTC-7, wrote:
> A 180 turn can definitely be performed within 600 feet, but then it has to be done quickly, with a good bank angle, and there is little room for adjustments in elevation. A safe 180 turn type of approach (naval aviator) requires (I think) bank angles that are less than 45 to have the room and time to adjust the rate of descent. In some way it is like having a curved base leg. But you may not do it safely if you are too close.
> Please Dan correct me on this, I am not used to do the naval pattern.
Look at the landing pattern in some IGC files on OLC. I don't think you will find many that use a 45 degree angle.
Just for curiosity, I looked at the recent landings at Hobbs of one of the competitors. When he passed the touchdown spot on downwind on July 1, he was roughly 450' above it and 1900' away. This is a ratio of 1:4, not 1:1. The next day his numbers were roughly 700' and 2200', for a ratio of 1:3.
I doubt if anyone can find many IGC files with numbers of 600' and 600'.
SoaringXCellence
July 13th 15, 12:31 AM
OK, I think we have (at least) two different ideas being discussed here, attached to the 45 degree value.
If you look at the article (which I have) one 45 degree reference is to the angle from the base-turn corner looking back to the touch down point. This is a common reference for almost any rectangular pattern described in a myriad of training manuals. It works pretty well for locating the base turn position, provided that enough altitude remains to complete the pattern.
There is the second reference to 45 degrees, which places the glider above the touch down point at the same distance laterally. This is the point (pun intended) where I think we have a few differences of opinion, mainly due to differences in altitude on the downwind. A lower performance (also slower) glider can easily be at 600' lateral displacement and have time and altitude to make corrections on the base leg due to the slower speed.
A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.
The article covers the extended downwind as a function of glider performance and clearly explains the need for adjustment.
Having said all that, at our field both a higher and wider pattern is typically flown and I believe the reference angle abeam the touchdown point is often closer to the 30 degrees noted by others.
MB
Bob Gibbons[_2_]
July 13th 15, 01:10 AM
An interesting discussion. As a long time user and proponent of the
TLAR method, I had not thought much about what the actual angles were.
Really easy to check with SeeYou and an IGC flight log. When I checked
my last 2 flights I found a pretty consistent 1km offset, with
altitude usually around 600 ft (opposite touchdown point, not pattern
entry). This is a 5:1 slope, about 12 deg. This is in a Ventus C.
Bob
On Sun, 12 Jul 2015 11:18:59 -0700 (PDT), wrote:
>> text deleted...
>
>Just for curiosity, I looked at the recent landings at Hobbs of one of the competitors.
>When he passed the touchdown spot on downwind on July 1, he was roughly 450'
>?above it and 1900' away. This is a ratio of 1:4, not 1:1. The next day his numbers
>were roughly 700' and 2200', for a ratio of 1:3.
>
>I doubt if anyone can find many IGC files with numbers of 600' and 600'.
Dan Marotta
July 13th 15, 01:40 AM
Well, that's the way I was trained in the Air Force and, as of today,
I've done it successfully 7,494 times. I guess it's not really as
dangerous as some would have you believe. Personally I find the long,
straight base leg to be much more difficult to execute well and much
easier to screw up. Your results may vary... :-D
On 7/12/2015 9:08 AM, wrote:
> A 180 turn can definitely be performed within 600 feet, but then it has to be done quickly, with a good bank angle, and there is little room for adjustments in elevation. A safe 180 turn type of approach (naval aviator) requires (I think) bank angles that are less than 45 to have the room and time to adjust the rate of descent. In some way it is like having a curved base leg. But you may not do it safely if you are too close.
> Please Dan correct me on this, I am not used to do the naval pattern.
--
Dan Marotta
Eric Greenwell[_4_]
July 13th 15, 02:49 AM
Bob Gibbons wrote on 7/12/2015 5:10 PM:
> An interesting discussion. As a long time user and proponent of the
> TLAR method, I had not thought much about what the actual angles were.
>
> Really easy to check with SeeYou and an IGC flight log. When I checked
> my last 2 flights I found a pretty consistent 1km offset, with
> altitude usually around 600 ft (opposite touchdown point, not pattern
> entry). This is a 5:1 slope, about 12 deg. This is in a Ventus C.
>
> Bob
I found the same thing in the 4 or 5 of my flights that I checked that I
flew in my ASH 26 E, generally turning onto the base leg at 1000' AGL. I
don't think I could get down in time if I were to use 45 deg angle to
the runway while on downwind, even with the 40 degree landing flaps and
good spoiler.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm
http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf
On Sunday, July 12, 2015 at 5:31:27 PM UTC-6, SoaringXCellence wrote:
> A faster, higher L/D glider needs a lot more distance/time to dissipate energy and being 600' laterally abeam the touch down would create a significant challenge, both with the turns required to intercept final and the 45 degree base base turn reference.
Not really. EASA CS-22 paragraph 22.75 under which most high performance gliders were certificated says:
"It must be shown that the sailplane has a glide
slope not flatter than one in seven at a speed of
1·3 Vso with air brakes extended at maximum weight."
So basically all JAR-22/CS-22 gliders have less than 7:1 L/D with the spoilers open.
I've done several 45 degree angle of depression approaches with an early model DUO and it worked out fine.
Yes really. Starting 1000 ft agl at 1000 ft from the runway, and following the standard pattern, it would be 1000 ft to the turn to base, 500 on base turn, 400 on base, 500 on final turn and a 1000 for final. Total 3400 ft. opening full brakes for all this distance, at 1 on 7 you lose close to 500 feet. And you started at 1000 agl, so you are still 500 ft too high. You need more powerful brakes and flaps. But you shoudn't be using full airbrake during the whole pattern, it is better to use half.
Please check your traces on seeyou, or check how far you are from your home runway using google earth, a rough estimate is enough. You will be surprised.
I think you may be believing you fly with a 45 degree dip angle (1:1) to the runway when in fact it is more like 30 degrees (1:2). Just a matter of perception. As long as you keep it doing it like that you can call that angle 100 degrees or pi or a million, it is still safe. And if you teach somebody "this is the way it should look", that student will retain in his visual memory that angle, or slope, and it will be safe. But I am afraid of people measuring 600 feet from the runway (easy on google earth) and trying to fly a pattern at that distance next time, it is too close to the runway.
I believe you can land the Duo from 600 feet away. I don't believe you can have a real base leg when you do that.
kirk.stant
July 13th 15, 04:03 PM
It's always surprised me that the 360 overhead pattern hasn't been taught in glider flying, because it is probably the easiest way to setup a consistent pattern into an unfamiliar field.
The military way, you fly over the field at pattern height and above pattern speed, make a 180 turn once past your touchdown point, slow and configure on downwind (which is located by the radius of your turn at a higher than approach speed), then when the angle to the touchdown point "looks about right", do a 180 turn to final. No problem overshooting final (unless you neglect a strong crosswind) since you know you can do the same 180 turn (or 2 90s to check final) as you did to get your downwind distance. Easy to adjust by waiting for the right angle to the field to start the turn.
If you like a longer base, then just add a short crosswind leg after an intial 90 turn; your base will be about the same length (use time to set the distance, say a 5-count before the second 90 turn to downwind.
This is not new, militaries have been doing it since before WW2, and it has the beauty that it works anywhere with no ground references needed.
Unfortunately, if you do it at most glider fields with other glider traffic in the pattern you will probably fly you pattern way inside them and cut them off!
If you think about it, it's a variation of how XC students are taught to fly a pattern for an off field landing.
Finally, I really think glider pilots (well, all pilots) should be able to setup a successful landing from just about anywhere near the airfield, from a steep straight-in to a button-hook reversal when you realize the wind just switched directions.
It's called airmanship...
Kirk
66
Brian[_1_]
July 13th 15, 04:39 PM
As mentioned it is pretty easy to review IGC files and see what one is actually doing. I agree telling students to use about 45 degrees is good as that is what they will percieve it at. I am one that if asked would have said I was probably between 30 and 45 degrees abeam my touch down point. Seeyou says different here are the number for 7 of me recent flights.
Altitude(ft) Distance (ft) Angle(deg)
870 2904 16.7
1053 2270 24.9
1699 3326 27.1
1751 4540 21.1
823 1900 23.4
1072 3500 17.0
951 3273 16.2
average 20.9
minimum 16.2
maximum 27.1
Charlie M. (UH & 002 owner/pilot)
July 13th 15, 04:43 PM
On Monday, July 13, 2015 at 11:03:41 AM UTC-4, kirk.stant wrote:
> It's always surprised me that the 360 overhead pattern hasn't been taught in glider flying, because it is probably the easiest way to setup a consistent pattern into an unfamiliar field.
>
> This is not new, militaries have been doing it since before WW2, and it has the beauty that it works anywhere with no ground references needed.
>
> If you think about it, it's a variation of how XC students are taught to fly a pattern for an off field landing.
>
> Finally, I really think glider pilots (well, all pilots) should be able to setup a successful landing from just about anywhere near the airfield, from a steep straight-in to a button-hook reversal when you realize the wind just switched directions.
>
> It's called airmanship...
>
> Kirk
> 66
I think you meant, "With no altimeter reference", not "Ground reference".
I use the same basic pattern for my home field as well as "off airport". You should always practice what you'll use.
An off airport landing can be stressful enough, why add yet another thing to deal with/stress out over?
And yes, I tend to agree with the "airmanship" comment.
A rectangular flight path is a very useful, easy to use tool when landing - especially during a strange field or off field landing.
It allows inspection of the chosen landing area, obstructions, slope, animal holes, wind, etc.
A disciplined landing pattern is practiced time and time again while learning - then is used in case it is needed at a strange location.
Inspecting common off field landing GPS traces, it is very common to observe pilots demonstrating the "wandering around" method while they desperately search for elusive lift - finally committing to the actual landing with an abbreviated, undisciplined landing pattern.
At one time, we actually taught our students to perform landings without an altimeter reference. The altimeter was covered as they entered the landing pattern. We stopped doing this because of liability concerns.
The TLAR method as described in the Glider Flight Training Manual explains the downwind leg is flown "no closer than a 45 degree angle to the landing surface" it goes on to explain the importance to have enough spacing to accommodate a proper length of the all-important base leg. A 30 degree angle is suggested as being more appropriate to ensure a reasonable length base leg that can easily accommodate judgments of both flight path and dive brake applications.
The text book further explains if the downwind leg is flown correctly, the turn onto the base leg will normally occur after passing a 45 degree angle looking back to the intended touchdown point - well within the landing area.. One of the most common errors is to turn too early and be so high that full dive brakes are necessary.
Pilots need to understand it is not normal to need either full dive brakes, or no dive brakes on the final approach, and this is a way to recognize if the landing pattern was flown correctly.
We have operated Ridge Soaring Gliderport for 40 years, and during that time, we have seen (probably) thousands of gliders landing long on our 3,300 ft runway. They wanted to stop near the tiedown area where most pilot stop, but make the common errors seen at every gliderport everywhere and end up too high and too fast on the final approach.
Off field landing accidents almost always involve landing much too long.
We have had exactly two gliders land short of our runway in the 40 year period.
Without taking the time or resources to examine every glider landing accident, The statistics will show the statistics are similar to our observations..
There is more to this subject, and this format is not appropriate for such discussions.
Tom Knauff
kirk.stant
July 13th 15, 06:21 PM
On Monday, July 13, 2015 at 10:44:00 AM UTC-5, Charlie M. (UH & 002
>
> I think you meant, "With no altimeter reference", not "Ground reference".
By "Ground Reference" I meant using a known feature on the ground to initiate actions in the pattern: IP at the lake, turn downwind over the farm, base over the gas station, etc. The airfield/landing zone is the only "ground reference" that should be used.
Agree, once the pattern is started, what's the point of looking at the altimeter?
Kirk
Charlie M. (UH & 002 owner/pilot)
July 13th 15, 08:18 PM
On Monday, July 13, 2015 at 1:21:43 PM UTC-4, kirk.stant wrote:
> On Monday, July 13, 2015 at 10:44:00 AM UTC-5, Charlie M. (UH & 002
> >
> > I think you meant, "With no altimeter reference", not "Ground reference".
>
> By "Ground Reference" I meant using a known feature on the ground to initiate actions in the pattern: IP at the lake, turn downwind over the farm, base over the gas station, etc. The airfield/landing zone is the only "ground reference" that should be used.
>
> Agree, once the pattern is started, what's the point of looking at the altimeter?
>
> Kirk
Ahhhhh..... Gotcha. Correct I don't use/didn't teach using fixed ground references, the angle was all it took.
Thus if you started early in the pattern (and you used angles), you should be further away "if it looks OK".
If you started low (and you used angles), you should be closer "if it looks OK".
Farmer Browns field does not have the lake/tree/parking lot/etc. your home field does, so the angles work there as well.
We're in agreement. ;-)
Squeaky
July 14th 15, 02:10 PM
I routinely look at traces for the patterns flown to our airport, and I fly closer than all but one or two (out of roughly 75 pilots) to the runway. Measuring traces, I fly roughly 1000' offset from the runway (800' out to a max of 1200'). Entering the pattern (TLAR) and using standard trigonometry, I may be no closer than a 45 look down to be at 1000'out. I do not like to be closer than that, and I flew USAF closed patterns in a previous life. Abeam touch down point, I look to be not lower than, and hopefully right near 30 degree look down/dip...less than 30 degrees I feel low and move it in and turn in sooner. I tend to do curvilinear patterns all the way around from this range and it is smooth and easily corrected at half speed brakes.
Measuring on Google Earth, to make the same turn from 600' seems like it would require me to fly way past my normal turn in point (45 back) or really play for a full speed brake, higher bank turn--needing a much higher level of flying perfection to make the landing spot than one should safely plan for. Simple math, 2D flight: 30 degree banked turn at 55 knots = 932 foot turn diameter. Same 55 knots, 45 degree bank = 538 foot turn diameter--not much margin for error at 600' offset (Seen anyone doing that for 180 degrees of turn and maintaining full boards to get down?? Didn't think so). I routinely fly the 30 degree bank around so I guess the math is close.
I agree with others based on the traces I've seen. If someone is claiming they use 45 degree dip/lookdown abeam touchdown point, on downwind, they aren't judging the angles correctly. I see most high performance sailplanes at least 2000 to 2500 feet away on average-much further than my little Pilatus likes to be. Which is fine, if they are consistently landing correctly as stated, that is TLAR to them no matter what they choose to name that angle. Having spent years rolling into 10, 20, 30, 45 and 60 degree dive bomb patterns, I can agree with others: they are thinking they are steeper than they really are (until they get more practice most new guys are always shallow). Same reason most pilots do not really get to 45 and 60 degrees of bank in thermals when they say they do....
Oh, and Kirk, I still do come up initial, pitch out and land in my glider like we did in fighters. The radio call confuses half the club: "Inbound, 1 mile north for initial, left break, stop south."
Squeaky
Bruce Hoult
July 17th 15, 05:09 AM
On Sunday, July 12, 2015 at 2:40:56 AM UTC+12, wrote:
> In the latest edition of Soaring magazine there is an article about TLAR. For those not familiar with TLAR, it is a landing approach teaching method that is based on angles as opposed to elevations and distances.
> Using angles automatically compensates for variations in altitude. On downwind , if you are high, you fly further away from the runway, if you ar low you fly a shorter pattern. The TLAR method is superior and safer than trying to teach fixed distances and specific altitudes for turns.
> However, I found a problem with something said in the article, but being the author a very recognized figure in the world of soaring, I was hesitant to write about it. I am refering to the dip angle between the glider and the runway on the downwind leg.
> The article states "The pattern shpuld be flown so on the downwind leg, opposite the touchdown point, the pilot is about 600 feet above the ground looking down at the touchdown point at a 45 degree angle". That angle looks too high for me, and I think it could be dangerous.
> I've always thought that angle should be more around 25 degrees, which would produce close to a 1-on-2 slope, as opposed to the 1-on-1 slope of 45 degrees.
> The 25 degree angle will put you at around 1300 feet from the runway, or close to a quarter mile away when you are at 600 ft agl.
> Getting too close to the runway prevents the pilot from having a good base leg where you can better judge your position to enter the very important base-to-final turn. In the worse case scenario, being too close will force you to use very steep banks or going for a button hook turn. New pilots and many old pilots may try to force the turn with rudder, and we all know how bad that can end.
> Is 600 ft too close? I'd say it is. I'll use a typical example. In calm conditions, many gliders fly a pattern at 50 knots. In theory, the radius of a 45 degree bank turn flown at that speed is 220 ft. But that doesn't take into consideration that you start the turn from zero bank, bank to 45 degrees, stay in the bank and unbank back to zero, so at the end you have a spiral turn, followed by a circular turn, followed by another spiral. If we assume it takes 2 seconds to bank to 45 degrees, the net effect is that your turn has an equivalent radius of 310 feet. When I repeat the calculations with a 30 degree bank, the equivalent radius of the turn is 440 feet.
> I am trying to spare you from the equations, but if you don't believe me, look at your flight traces in google earth, or just using google earth, measure the distance from the location of your downwind leg to the runway. On your home airport, you should have a good idea of more or less where that is. I assure you that nobody is flying at 600 ft, it would scare you. Also, take a look at the angle to the runway when you are flying. Definitely not 45 degrees. Even on your chair as you read this look down to your left or right at 45 degrees and imagine the runway is at the floor.A little steep?
I reviewed a number of my videos of flights.
I'm pretty much always passing the touchdown point at 550 - 600 ft. In some cases I'm 400m - 500m to the side. That seems to invariably be in rough turbulent conditions, and I'm then making a full brake continuous turn until on finals, and then reducing brake as required.
Most of the time when I'm flying I'm more like 600m to the side.
When directing new students I seem to usually take them about 800m to the side. This gives more time on base leg, and possible to line up with the runway with a less aggressive turn.
All flights in a DG1000.
With first time students (trial flights) I also often open full brakes just after turning final for enough time that they can observe for themselves that we're not going to make the field, then go to closed brakes to show we can still fly well past the far end of the field, and then resume a standard half brake approach. Many people express doubts that you can land an unpowered aircraft precisely, or think that you're likely to get into an unrecoverable situation. It really isn't a problem if you're paying any kind of attention at all, and this demonstration quickly clears that misconception up.
Dan Marotta
July 17th 15, 04:40 PM
Well I finally figured out how to measure on google maps and yesterday I
made a close observation of my ground track on downwind. The results
surprised me: At 800' AGL abeam the numbers, I was about 2,000 ft
displaced from the runway. This is a bit wider than I usually fly but
the angle worked out to about 22 degrees or about half what I expected.
I'll try again next time a bit closer, but I think a 45 degree look down
will make for a very steep banked 180 degree turn to final and will
probably require about a 45 degree look back at the touchdown point.
This is fun!
On 7/16/2015 10:09 PM, Bruce Hoult wrote:
> On Sunday, July 12, 2015 at 2:40:56 AM UTC+12, wrote:
>> In the latest edition of Soaring magazine there is an article about TLAR. For those not familiar with TLAR, it is a landing approach teaching method that is based on angles as opposed to elevations and distances.
>> Using angles automatically compensates for variations in altitude. On downwind , if you are high, you fly further away from the runway, if you ar low you fly a shorter pattern. The TLAR method is superior and safer than trying to teach fixed distances and specific altitudes for turns.
>> However, I found a problem with something said in the article, but being the author a very recognized figure in the world of soaring, I was hesitant to write about it. I am refering to the dip angle between the glider and the runway on the downwind leg.
>> The article states "The pattern shpuld be flown so on the downwind leg, opposite the touchdown point, the pilot is about 600 feet above the ground looking down at the touchdown point at a 45 degree angle". That angle looks too high for me, and I think it could be dangerous.
>> I've always thought that angle should be more around 25 degrees, which would produce close to a 1-on-2 slope, as opposed to the 1-on-1 slope of 45 degrees.
>> The 25 degree angle will put you at around 1300 feet from the runway, or close to a quarter mile away when you are at 600 ft agl.
>> Getting too close to the runway prevents the pilot from having a good base leg where you can better judge your position to enter the very important base-to-final turn. In the worse case scenario, being too close will force you to use very steep banks or going for a button hook turn. New pilots and many old pilots may try to force the turn with rudder, and we all know how bad that can end.
>> Is 600 ft too close? I'd say it is. I'll use a typical example. In calm conditions, many gliders fly a pattern at 50 knots. In theory, the radius of a 45 degree bank turn flown at that speed is 220 ft. But that doesn't take into consideration that you start the turn from zero bank, bank to 45 degrees, stay in the bank and unbank back to zero, so at the end you have a spiral turn, followed by a circular turn, followed by another spiral. If we assume it takes 2 seconds to bank to 45 degrees, the net effect is that your turn has an equivalent radius of 310 feet. When I repeat the calculations with a 30 degree bank, the equivalent radius of the turn is 440 feet.
>> I am trying to spare you from the equations, but if you don't believe me, look at your flight traces in google earth, or just using google earth, measure the distance from the location of your downwind leg to the runway. On your home airport, you should have a good idea of more or less where that is. I assure you that nobody is flying at 600 ft, it would scare you. Also, take a look at the angle to the runway when you are flying. Definitely not 45 degrees. Even on your chair as you read this look down to your left or right at 45 degrees and imagine the runway is at the floor.A little steep?
> I reviewed a number of my videos of flights.
>
> I'm pretty much always passing the touchdown point at 550 - 600 ft. In some cases I'm 400m - 500m to the side. That seems to invariably be in rough turbulent conditions, and I'm then making a full brake continuous turn until on finals, and then reducing brake as required.
>
> Most of the time when I'm flying I'm more like 600m to the side.
>
> When directing new students I seem to usually take them about 800m to the side. This gives more time on base leg, and possible to line up with the runway with a less aggressive turn.
>
> All flights in a DG1000.
>
> With first time students (trial flights) I also often open full brakes just after turning final for enough time that they can observe for themselves that we're not going to make the field, then go to closed brakes to show we can still fly well past the far end of the field, and then resume a standard half brake approach. Many people express doubts that you can land an unpowered aircraft precisely, or think that you're likely to get into an unrecoverable situation. It really isn't a problem if you're paying any kind of attention at all, and this demonstration quickly clears that misconception up.
--
Dan Marotta
It may be too high, but it's hardly dangerous. Since you can basically turn the glider around virtually on a dime (think rope break), Your distance from the runway is not critical. And you can easily lose 600 feet, or even a 1000 feet on final by just opening the dive brakes and diving at the end of the runway (don't try this in a power aircraft however).
I thought we were discussing traffic patterns, not the capabilities of pilots and machines.
As I've mentioned before, it is possible to land from many combinations of heights and distances to the runway. In this thread we are talking about a normal pattern with enough spacing from downwind to the runway, in order to arrive to a final stabilized approach with the right amount of height, speed, distance to the runway, etc.
We are trying to prevent excessive slips and manouvering in the pattern.
When landing accidents are looked at, the most common landing accident is landing too long. As I stated before, in 40 years at Ridge Soaring Gliderport, we have had two gliders land short of the runway. Probably thousands have landed well beyond where they intended - but not off the far end.
A well placed, proper length base leg is a very important judgment tool - especially when landing at a strange field. Speed control is also important as is dive brake technique.
Airspeed should be proper for the conditions and constant. The dive brakes are a good indicator how a pilot has performed the landing pattern. Full dive brakes should not be needed. Of course, a no-dive brake landing is also not using good judgment - but this is relatively rare.
A precision- flown landing pattern is based upon the need for a reasonable length base leg at a reasonable height flown at a reasonable airspeed, with a reasonable dive brake setting.
Tom Knauff
On Sunday, July 19, 2015 at 7:34:18 AM UTC-6, wrote:
> I thought we were discussing traffic patterns, not the capabilities of pilots and machines.
> As I've mentioned before, it is possible to land from many combinations of heights and distances to the runway. In this thread we are talking about a normal pattern with enough spacing from downwind to the runway, in order to arrive to a final stabilized approach with the right amount of height, speed, distance to the runway, etc.
> We are trying to prevent excessive slips and manouvering in the pattern.
"The Pattern" doesn't need to be capitalized or raised to a level of importance it doesn't deserve - it's just a tool to help a pilot make a safe landing. Good pilots will modify it as necessary it to fit conditions. Those less cued in will fly the same pattern every time regardless of conditions - and sometimes end up in the Mesquite.
If a pilot is concerned about sudden height loss due to strong sink or wind shear, flying a pattern close and high makes sense.
I've always flown in the western US where strong sink and wind shear can be expected so my patterns tend to be high and close. Many times I've landed using very little spoiler due to extreme sink - and been very thankful I'd had so much excess energy in the pattern. I get really nervous when riding with someone making a wide, low pattern.
Bob Pasker
July 22nd 15, 07:05 PM
When I transitioned to gliders, I lost two very important visual cues which I used flying airplanes: the center line or runway edges, and a aiming point marking, whether it's just a (possibly displaced) threshold, or at IFR airports, the piano keys, TDZ, or aiming point markings.
In airplanes, on a stabilized approach at 500ft, with proper wind correction, I can land within commercial standards at whatever point on the runway I like, on the centerline.
But gliderports are different. They have a wide variety of geometry (eg Estrella has a narrow strip and Seminole lake is 200ft wide), a combination of surfaces (eg part dirt, part tarmac), and there may be other aircraft off to the side that just landed or are staged at the departure end, or another glider landing right behind. Or there may be three parallel runways (Air Sailing, Estrella), and the ship landing in front of me doesn't announce which one he's going to land on, so I can't decide which runway I'm going to land on until I can see him on final. I've even had airplanes ask me to "extend downwind" so they can do a low pass in the opposite direction. Then there's the glider tows and departures which add another degree of complexity.
Furthermore, I have gotten yelled at for landing on the centerline when there's another ship off to the side on the runway (there were hundreds of feet between us). I've gotten yelled at for overflying aircraft to land beyond it. I've gotten yelled at for landing on the threshold, and coming to a stop well before another craft, etc, etc. So sometimes in the pattern when there's someone on the single runway, in the back of my head, I'm wondering not "where's the safest place to land," but "how can I land without the other pilot yelling at me", a narrative I then have to reject.
So I have had to adapt my landing technique to this very dynamic pattern and landing environment.
The result is something that I'm sure to get flamed for: when entering the airport area, I will have my pre-landing checklist completed, arrive with enough altitude to figure out what's going on (traffic and winds) before committing to land, remain close enough to the airport that I can choose to land at any time, and fly at L/Dmax. When I'm #1 and I have a trajectory for every aircraft landing, taking off or taxiing, then I commit to a landing spot, and make whatever is the appropriate pattern and approach given the circumstances, but no more shallow than a normal glider approach.
I feel that this gives me the most time to decide what I'm going to do in this dynamic landing environment, and I am continuously in a position to land should I need to at any time.
--b
https://www.faasafety.gov/files/gslac/courses/content/35/376/Stabilized%20Approach%20Concept.pdf
Bob Whelan[_3_]
July 22nd 15, 08:27 PM
On 7/22/2015 12:05 PM, Bob Pasker wrote:
> When I transitioned to gliders, I lost two very important visual cues which
> I used flying airplanes: the center line or runway edges, and a aiming
> point marking, whether it's just a (possibly displaced) threshold, or at
> IFR airports, the piano keys, TDZ, or aiming point markings.
>
> In airplanes, on a stabilized approach at 500ft, with proper wind
> correction, I can land within commercial standards at whatever point on the
> runway I like, on the centerline.
>
> But gliderports are different. They have a wide variety of geometry (eg
> Estrella has a narrow strip and Seminole lake is 200ft wide), a combination
> of surfaces (eg part dirt, part tarmac), and there may be other aircraft
> off to the side that just landed or are staged at the departure end, or
> another glider landing right behind. Or there may be three parallel runways
> (Air Sailing, Estrella), and the ship landing in front of me doesn't
> announce which one he's going to land on, so I can't decide which runway
> I'm going to land on until I can see him on final. I've even had airplanes
> ask me to "extend downwind" so they can do a low pass in the opposite
> direction. Then there's the glider tows and departures which add another
> degree of complexity.
Ignoring the "extend downwind (for apparently purely self-gratifying reasons)"
silliness/stupidity, and not intending to be dismissive in any way of
previously-acquired/of-diminished-value-to-glider-patterns, my knee-jerk
response to "those losses" is something along the lines of, "Well, duh! That's
what learning how to "assess/fly glider patterns" is all about!" Safely and
effectively dealing with "those losses" I mean...
Sure it's important to be able to fly a stabilized approach, whether in a
power plane or a glider, in "standard conditions to a known/standardized
destination," but the essence of "a good glider pattern" (so it seems to me)
is the ability to bring to bear all one's talent and experience to each and
every landing pattern, so that you're *still* able to fly a "reasonably
stabilized approach" and *still* "hit your spot," regardless of whatever
non-standardization local geography dictates. So being aware of those
differences between "your average power-based patterns" and "your average
glider (and off-)field/pattern" is entirely normal and arguably good, while
using the absence of standardization as an excuse for sub-par glider patterns
is not so good! :)
- - - - - -
<Snip...>
> So sometimes in the pattern
> when there's someone on the single runway, in the back of my head, I'm
> wondering not "where's the safest place to land," but "how can I land
> without the other pilot yelling at me", a narrative I then have to reject.
>
> So I have had to adapt my landing technique to this very dynamic pattern
> and landing environment.
>
> The result is something that I'm sure to get flamed for: when entering the
> airport area, I will have my pre-landing checklist completed, arrive with
> enough altitude to figure out what's going on (traffic and winds) before
> committing to land, remain close enough to the airport that I can choose to
> land at any time, and fly at L/Dmax. When I'm #1 and I have a trajectory
> for every aircraft landing, taking off or taxiing, then I commit to a
> landing spot, and make whatever is the appropriate pattern and approach
> given the circumstances, but no more shallow than a normal glider
> approach.
>
> I feel that this gives me the most time to decide what I'm going to do in
> this dynamic landing environment, and I am continuously in a position to
> land should I need to at any time.
I've (rarely) been growled/whined/yelled at for a pattern or two into a busy
GA/glider field with 3 parallel runways (Boulder, CO) in the course of 3+
decades of being based there, strictly as a glider pilot.
Because I quickly decided that doing what you describe in the final two quoted
paragraphs just above, made eminent sense, and made it a firm habit to do
exactly the same thing (i.e. I never arrived back at the pattern "needing the
pattern *now* "), I like to believe that's why "rarely" proved to be the case!
YMMV,
Bob W.
Dan Marotta
July 23rd 15, 01:59 AM
Hang around RAS long enough and you'll get yelled at here, too! =-O
On 7/22/2015 12:05 PM, Bob Pasker wrote:
> When I transitioned to gliders, I lost two very important visual cues which I used flying airplanes: the center line or runway edges, and a aiming point marking, whether it's just a (possibly displaced) threshold, or at IFR airports, the piano keys, TDZ, or aiming point markings.
>
> In airplanes, on a stabilized approach at 500ft, with proper wind correction, I can land within commercial standards at whatever point on the runway I like, on the centerline.
>
> But gliderports are different. They have a wide variety of geometry (eg Estrella has a narrow strip and Seminole lake is 200ft wide), a combination of surfaces (eg part dirt, part tarmac), and there may be other aircraft off to the side that just landed or are staged at the departure end, or another glider landing right behind. Or there may be three parallel runways (Air Sailing, Estrella), and the ship landing in front of me doesn't announce which one he's going to land on, so I can't decide which runway I'm going to land on until I can see him on final. I've even had airplanes ask me to "extend downwind" so they can do a low pass in the opposite direction. Then there's the glider tows and departures which add another degree of complexity.
>
> Furthermore, I have gotten yelled at for landing on the centerline when there's another ship off to the side on the runway (there were hundreds of feet between us). I've gotten yelled at for overflying aircraft to land beyond it. I've gotten yelled at for landing on the threshold, and coming to a stop well before another craft, etc, etc. So sometimes in the pattern when there's someone on the single runway, in the back of my head, I'm wondering not "where's the safest place to land," but "how can I land without the other pilot yelling at me", a narrative I then have to reject.
>
> So I have had to adapt my landing technique to this very dynamic pattern and landing environment.
>
> The result is something that I'm sure to get flamed for: when entering the airport area, I will have my pre-landing checklist completed, arrive with enough altitude to figure out what's going on (traffic and winds) before committing to land, remain close enough to the airport that I can choose to land at any time, and fly at L/Dmax. When I'm #1 and I have a trajectory for every aircraft landing, taking off or taxiing, then I commit to a landing spot, and make whatever is the appropriate pattern and approach given the circumstances, but no more shallow than a normal glider approach.
>
> I feel that this gives me the most time to decide what I'm going to do in this dynamic landing environment, and I am continuously in a position to land should I need to at any time.
>
> --b
>
> https://www.faasafety.gov/files/gslac/courses/content/35/376/Stabilized%20Approach%20Concept.pdf
--
Dan Marotta
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