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.

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.

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

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.