3 degree glide slope tricks?

[jaylw314]

44 minutes ago, Lance Link said:

This is all very interesting and informative to me.  I had never thought about using the FAF, for example, to better teach myself to see the glide path.  (I do that with PAPI lights of course but kind of consider it cheating).  It a great idea and I'm going to try it.  I started IFR training right before the covid hit, but I did learn enough to enable me to used approach plates to work on this I think.  That in combination with the other tips will mean a lot of methods to practice, and combine to dial in a system that gives me consistency.

Here is something else interesting:  I got curious about this, so I did the trigonometry, and then went to Google Earth and Fore Flight 3D and looked up some out of the way airports I've landed at, and where I tended to turn base based on eyeballing.  I realize I been flying VFR approaches too high forever!  I was initially taught to turn base in a 172 at 400 ft agl 1/2 mile from the runway.  What the.....

For anyone interested, I found the tangent for 3 degrees is .052, and for 4 degrees it's .069, unless I'm bad at math.  So to figure out how far from the runway I should be for a given glide path, I divided my relative altitude at the point where I turn base by one of those numbers.  Based on landmarks, I seem to always be turning too early and/or too high.  And I do realize 3 degrees is really shallow for a light GA plane.  I might find higher looks and feels better.  But first, I need to figure out how to know where the heck I am.   

While it's good to have precise ways to crosscheck the Mark I Eyeball, do keep in mind that the most important mnemonic for VFR flying is still TLAR (That Looks About Right)  

[Hank]

5 minutes ago, jaylw314 said:

While it's good to have precise ways to crosscheck the Mark I Eyeball, do keep in mind that the most important mnemonic for VFR flying is still TLAR (That Looks About Right)  

And a good VFR landing is idle power with runway under the wheels! I prefer wheels rolling on the surface over how good it looks.

[Ragsf15e]

51 minutes ago, Hank said:

And a good VFR landing is idle power with runway under the wheels! I prefer wheels rolling on the surface over how good it looks.

Right, I’m with Hank on this one, so a bit steeper than 3 degrees on a vfr pattern is probably ok so you could have a chance to get to the runway if you have engine trouble.  If you establish a nice 3 degree glideslope at approach speed and then pull the power you’ll find your new aimpoint very short.  Closer to 4 degrees won’t make it every time from everywhere in the pattern but gives you a better chance.

 If you’re ifr, nice stable 3 degrees is good. Generally people are faster than normal final speed when on an instrument approach until they break out but would likely still fall short if they lose power.  If you’re imc and lose power, it’s a bad day.

[EricJ]

19 hours ago, jaylw314 said:

While it's good to have precise ways to crosscheck the Mark I Eyeball, do keep in mind that the most important mnemonic for VFR flying is still TLAR (That Looks About Right)  

Particularly because winds, terrain, traffic, obstacles, etc., all affect how you might want to fly a VFR pattern or approach.   Winds alone will change the glide path significantly if you use a consistent power/airspeed/configuration stabilized approach method.

Hadn't heard the TLAR acronym for a while, too. 

[V1VRV2]

A generic version of a pattern for most light singles should put you on a 3 degree glide slope if flown correctly. 90 kts in downwind... abeam the numbers reduce power, add your first flaps and start a gradual descent at about 300’ per minute. When you reach the 45 angle off the runway you should be at approx 750’. Add the next flap setting adjust power if needed and slow to 80 kts. Rate of descent should still be approx 300 ft per min. The turn on final should be your landing flap setting power as required and slow to 70 kts. Make final glide path and airspeed/power adjustments on the early final approach. Don’t overthink this. 3 degree glide path is not shallow. It’s normal. 

Edited June 24, 2020 by V1VRV2

[carusoam]

Some proponents of Mooney safety...

Minimize configuration changes in later stages of the traffic pattern...

They have gone to a continuous 180° turn, and start with landing flaps already put in and trimmed before descent....  (there is a name for this)

This helps to minimize the challenges of adding trim and configuration changes later...  re-trimming takes some time and distracts the pilot right in time for the turn to final...

Add in some strong cross winds... and some pilots forget about steep turns, and cross control, for some reason...

 

Sense of timing gets lost when multi-tasking gets high...

 

The turn to final is where things fall apart... far more often than engine failure on final... so having too much flap in too early, is not a big deal...

PP thoughts only, not a CFI...

Best regards,

-a-

[tmo]

3 hours ago, V1VRV2 said:

A generic version of a pattern for most light singles should put you on a 3 degree glide slope if flown correctly. 90 kts in downwind... abeam the numbers reduce power, add your first flaps and start a gradual descent at about 300’ per minute. When you reach the 45 angle off the runway you should be at approx 750’. Add the next flap setting adjust power if needed and slow to 80 kts. Rate of descent should still be approx 300 ft per min. The turn on final should be your landing flap setting power as required and slow to 70 kts. Make final glide path and airspeed/power adjustments on the early final approach. Don’t overthink this. 3 degree glide path is not shallow. It’s normal. 

And this, boys and girls, is why we have so many gear-ups ;-)

[tmo]

2 hours ago, carusoam said:

having too much flap in too early, is not a big deal

Back on a serious note, and with all due respect, I think there is value in the method that calls for full flaps once landing is assured. I realize it is a give-and-take, and it is much easier to nail a landing with power, but I try to go for steeper descents. If you have power, you can always go around!

[PTK]

On 6/24/2020 at 1:43 AM, carusoam said:

The turn to final is where things fall apart... far more often than engine failure on final... so having too much flap in too early, is not a big deal...

I have a very serious problems with this Anthony! Flaps should be used as needed and as much as needed. They should not be used early and indiscriminately. As if to check them off the checklist and get them out of the way! Do you need flaps on a gusty day for example? If so how much? Drag increases as more flaps are added so full flaps add maximum drag. Which leads to the other problem I have with your “...no big deal...” Adding flaps can be a very big deal and not so benign when done at the worst possible time, which is on the base to final turn. This introduces unbalanced drag when low and slow which leads to an uncoordinated condition. 

For anything more than takeoff flaps the drag increase overwhelms any lift benefit. Your adding “too much flap in too early is no big deal” is inefficient, wasteful and, at the wrong time downright dangerous.

[Hank]

5 hours ago, V1VRV2 said:

A generic version of a pattern for most light singles should put you on a 3 degree glide slope if flown correctly. 90 kts in downwind... abeam the numbers reduce power, add your first flaps and start a gradual descent at about 300’ per minute. When you reach the 45 angle off the runway you should be at approx 750’. Add the next flap setting adjust power if needed and slow to 80 kts. Rate of descent should still be approx 300 ft per min. The turn on final should be your landing flap setting power as required and slow to 70 kts. Make final glide path and airspeed/power adjustments on the early final approach. Don’t overthink this. 3 degree glide path is not shallow. It’s normal. 

And this is where generic advice falls apart. At 70 knots on final, I'll touch down in the next county--my stall speed in the landing configuration is 47 knots . . . While I do like this pattern, and the altitudes are close, I use 90 mph downwind and base, roll wings level on final at 85 mph and slow to actual-weight-dependent 70-75 mph on short final with stall horn coinciding with touchdown. My Owners Manual also specifically calls out Takeoff Flaps on downwind and adjust throttle, elevator and flaps as needed on final to touch down at the desired location; this often has me landing with Takeoff Flaps and trim very close to the Takeoff position as well, even at my former 3000' long obstructed home field. 

[Ibra]

For VFR, ideally 2 landings out of 5 should be done while keeping things tight/steep on speed/height/bank with minimal power/runway, that practice pays a lot in the long run, especially when the single engine stops 

Edited June 24, 2020 by Ibra

[Austintatious]

Lots of great suggestions in this thread.... I do not disagree with any of them.

What I would add is, if you are making a visual approach to a runway without a VASI/Papi... Just fly A VISUAL and don't worry about nailing a 3 degree slope.  Just try to fly a steady descent to the runway and look for obstacles.  

Also, I don't typically fly 3 degrees on a visual, typically 4 or 5, which gives me confidence I can make the runway if the motor stops.  There is no need to put myself down on such a flat descent in visual conditions.  There are also plenty of instrument approaches that are more than 3 degrees.  There is an ILS on the other side of the pond that is a 6 degree angl90190120

[toto]

This is in no way relevant to the question the OP asked, but ... The GTN series navigators have a convenient visual approach option that paints a GPS-derived glideslope over an extended centerline. Requires no published approaches (although I suspect there are some airports where it doesn't work - haven't seen one yet). 

I find it particularly helpful when VFR in a busy unfamiliar airport environment - you get a fake localizer+glideslope indication that definitely helps confirm the sight picture. 

 

[Lance Link]

I get all of the good tools and tricks we use, aim points, spot in the windscreen, that looks about right, all good techniques.  But, I really think the way this part of landing is taught is less than ideal.  Think about it.  The above diagram says fly downwind "alongside the runway".  But how far away from it?  I was taught 1/2 mile.  If we turn base at the 45 degree point, and end up at, say, 400' when we turn final just as an example, we will be 1/2 mile from the threshold.  We need to be 5800' from it for a 4 degree glide slope.  So we end up more than twice as high as we want to be.  Bad habits formed from this flawed concept have hampered my landings for years.  I'm sure most of us turn to final farther out than 1/2 mile, and I've started to fly downwind as much as 3/4 mile from the runway, and then turn base at more like 60 degrees, so as to end up turning base closer to a point where I am intersecting a glide slope of 3 or 4 degrees.  And the experiments continue!  

I realize it sounds like I am obsessing about this.  I know adjusting for these variables is a big part of the fun of flying.  And as crazy as it sounds I am just now getting tired enough of fighting to lose altitude on final to get low enough that I am finally seriously analyzing the subject, instead of trying to fix the problem by feel and experience.  The Mooney is more demanding that other planes, and is less tolerant of slop.  A Cessna will drop if you want it to.  The Mooney wants to fly.  That's why we have them.  But, I have taken a vow to quit the carrier landings.  They are hard on my nerves.  Thanks again everyone!    

[Ibra]

2 hours ago, Lance Link said:

And as crazy as it sounds I am just now getting tired enough of fighting to lose altitude on final to get low enough that I am finally seriously analyzing the subject, instead of trying to fix the problem by feel and experience.  The Mooney is more demanding that other planes, and is less tolerant of slop.  A Cessna will drop if you want it to

While Mooney will be tough to slowdown with stick forward and power than many "flying bricks" but you can still get it perfectly lined "on speed": try changing your visual aiming point ref for the pattern depending on your flying habits and conditions, if you find yourself overshooting or undershooting a runway consistenly for X reasons, try moving your aming point: assume anything from mid-runway up to 1/2 nm before runway threshold and slightly left/right as your new aiming point? then fly that as pattern reference and only change to runway numbers when established on final? this avoids turning early/late to final, coming high/low on final and helps a lot: for engine off practice, as moving you ref point keep some options open and protects you from overshoot or undershoot 

Edited June 25, 2020 by Ibra

[carusoam]

LL with the Cool J...

Great thoughts...   see if there are any Mooney standards you might pick up here...Let me know if I missed something....

Logic drives the traffic pattern... if you start too close to the runway... you magically run out of base leg....

 

Altitude control...

There is a lot of energy to lose going from 90ias in the traffic pattern to 65 near the runway... It starts with how far agl you are... my home drome is 1200’ agl..... and how good your air brakes work...

In ideal conditions... the altitude to lose would be about 1/3, 1/3, 1/3....  (done by design)

• alt lost from abeam the numbers to base turn...
• alt lost from base to final turn...
• alt lost from from final to the ground...
   

Distance from the runway... people use the wing as a measuring stick...

• Runway on the wing tip is pretty nice...
• Runway off the wing tip is pretty far...
• Runway 1/2 way out on the wing, getting close... (Leads to a very short base, hard to recover from)
• Runway straight down.... great for spiral to land...

 

Power control...
Each of MP is worth about 100fpm...   

So... 16”MP in the TP... set up for initial descent using 13” should net 300fpm
geing stable in the traffic pattern starts miles away for some....

 

Trim control...

hold the nose up to set the airspeed you are looking for... raise the trim.

Release the yoke momentarily... does the nose go up or down... Hold the yoke, adjust the trim again... Release... (quick, no waiting)

Quality check...

As you approach the 45° mark... speed and altitude check... did you lose 1/3, are you going 80?, is your X-wind as strong as expected?

 

repeat going down base...

You are probably high by design... expect a power cut... 1”?

Not high... no power cut required...

If you are adding flaps, retrim at the same time... helps to have electric trim for this....

Check trim releasing the yoke...
 

Low... Something isn’t working right...   you are adding power back in... and dragging the plane around the TP... expect that you will easily transition into the back side of the power curve with the nose high trying to follow the glide path...

If you run into this it is time to get some instructor time... for practice.

If you goofed up the initial spacing from the runway, or the cross wind blew you in close... Base Leg is where you find your mistake... and not enough time to correct it without destabilizing the approach...

 

This is an extreme test of multi-tasking skills...

• Maintaining distance away from the runway...
• Setting descent rate
• Setting deceleration rate
• Check altitude
• Checking speed
• retrimming
• resetting power
• Checking gumps
• Changing configuration
• communicating position reports 
• scanning for people goofier than you....
• Checking ground speed is less than IAS... (GPS vs air speed, ground speed better be slower than air speed)
• Seeing windsock as expected in the expected direction...

Everyone probably does this differently... but all of these things are probably what you are doing... one way or another...

In my world... power controls descent rate... until short final... 

Then the nose is pointed at the ground, the altitude is set by the buildings and trees on final approach...

Power is pulled all the way out when the runway ‘is made’

Not mentioned... how many times you check the IAS, how many times you adjust the bank angle, how slowly you bank, or how coordinated your rudder is...   more often is better...

Lots of multi-tasking...

PP thoughts about power control in the traffic pattern... not a CFI...
For conversational use only...

Best regards,

-a-

[RLCarter]

On 6/20/2020 at 12:50 PM, Lance Link said:

I've always been told that identifying a 3 degree glide slope, absent IFR instrument help or lights, just has to be done based on experience.  Any other tricks?

In particular, if I am on final, full flaps at 70 knots in a J model for example, and the HSI shows 3 degrees, am I on a 3 degree glide slope?    I gather that would mean the plane is flying straight down the glide slope line and is not pitched up any to maintain the 70 knot approach speed.  If this is true, seems like it would be a fairly good cross-reference.  

Any thoughts or tips?  Thanks!  

Go fly an ILS with a 3° GS in VMC and look out the windscreen, then practice that sight picture 

[Ibra]

3 hours ago, RLCarter said:

Go fly an ILS with a 3° GS in VMC and look out the windscreen, then practice that sight picture 

Assuming you have enough visibility, at more than 2nm away from the runway threshold, it should visually sit 3deg bellow the horizon all times but the horizon picture and lateral position of the runway dot one the screen will depend on power & speed config & wind setting 

Most of the time I reallyvcan't spot the runway from 5nm final approach fixes, hardly from 10nm FAF but I know it is there slightly bellow the horizon, and in descent VMC it should always visible from 3nm FAFs, but it is much easier to spot on synthetic vision screens first as they tell you where to look even on visual flying, long story short assume it is not there far away than 3nm final unless there is a big town nearby or you know the local area

For IFR flying, I think it is poor practice to try spotting the runway that far, you fly head down the ILS neddles dead to the minima and then open your eyes: you see it land, no go missed, nothing worse than confusing surface sights/lights with runway or end up with VFR aproach in IMC bellow/above glide path...

Edited June 26, 2020 by Ibra

[RLCarter]

1 hour ago, Ibra said:

Assuming you have enough visibility...........much easier to spot on synthetic vision screens first 

the OP is talking about flying a 3° approach in VMC with no GS or lights for guidance .... assuming there is synthetic vision available
 

[bradp]

On 6/21/2020 at 7:31 AM, midlifeflyer said:

Yes, but no No NO!

You are asking about "absent IFR" and I think that means a visual approach. That's a visual maneuver and should be done with outside references. You should be able to maintain the proper path - horizontally and vertically - and at the proper airspeed, with the instrument panel completely covered. 

A couple of tips to develop that (although  I pull it on pilots all the time, and will not even solo a student until they can, chances are you can already do it - no one so far has had any difficulty). 

• use the VASI or PAPI, but as a training aid to learn what the glide path looks like without them. In theory, you  can do that with a needle, but the idea is to get you looking outside. 
• groundspeed X 5 is a target for a 3 degree path. Yes, using IAS,  there will be variation for wind and density altitude, but we are using it as a training aid, not as an instrument target.

Mark is absolutely correct.  I will add that it’s a useful situational awareness tool to overlay an approach during visual approach and landing to a runway.  I got into this habit when I was flying into Richmond VA one night, was in right traffic for 20 and got turned around on final and lined up for 16 instead.  Since then I’ll back up my visual with an instrument approach when flying VFR at night or to an unfamiliar airport. 
 

I use 300 AGL per nautical mile.