Stable Approaches

B

Bob Turner

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There is a thread on the J3 forum about flying taildraggers. I have to admit - I really didn't understand what they were getting at.

I have been teaching tailwheel for a half century now - crosswind training is my specialty. The feds now want stabilized approaches - I had a student flunk a checkride because he did not stabilize the approach at 60 mph with power. The examiner could have said "show me a power on 60 mph approach from two miles out" and he would have done a beautiful job. The FAA apparently will not allow an examiner to specify exactly what they want; the student gets to guess at the configuration and airspeed the examiner has in mind.

I have no idea what a stabilized approach is supposed to be - I can be stable at 40 mph power off or 80 mph power on - and I am (or was) willing to teach whatever the examiner wants - just tell me ahead of time. The Decathlon does a beautiful stabilized ILS at 90 indicated.

Rant over.
 
Bob Turner said:
I have no idea what a stabilized approach is supposed to be
Click to expand...

The airlines have a program called FOQA, it stands for flight operations quality assurance. Data from flight data recorders is evaluated to see how much deviation there is from what has been established as standard procedures and situations or published procedures that create high levels of deviations are analyzed to figure out why they are problematic. We used to be able to do just about anything with the planes and if there wasn't an incident, we were good. I won't/can't type examples!

Something that came from the analysis of this data, over the years since the program was started, is that when a pilot makes an approach that is well planned and well executed so as to be "stable" by a certain point on the approach, the landing is usually uneventful; on speed and in or near the touchdown zone. When you are exposed to this training and the data that supports it, it is !!!CRAZY!!! to see just what some approaches look like and what happens over the runway as the pilots attempt to land.

Where I work we try to be at certain configurations and airspeeds by certain altitude "gates" above the ground and if we aren't fully configured and on speed by 500 ft, we call "unstable, going around". Where go-arounds used to be considered a non-normal event that required a report to be filed, we now view them as a part of operating large airplanes into busy airports. The stigma surrounding go-arounds as a failure has been removed so pilots won't feel pressured to continue bad approaches. Today's airline pilots are much more aware that perfect doesn't exist and that being able to recognize deviations from standard and call them out in real time is part of the job.

When it comes to general aviation, haven't you ever noticed that when you've nailed a stable continuous descent to the runway the landing just seems to fall into place on its own? How many of you carry power to a certain point and then pull it to idle for the last few hundred feet when the runway is made? I guess "stable" for GA might be to have airspeed stabilized by a certain altitude above the runway and to then try to fly the final glide path without large changes in pitch or power to the touchdown point and to land within a certain distance from what you have been shooting for. For us we aim to land within 3000' of the touchdown zone (the fixed distance markers on an instrument marked runway) or the first third of the runway, whichever is less, and are technically required to go around if we miss it. Watching computer re-creations of bad landings with transport category airplanes is gut wrenching, at least for me it is!! You should see me squirm!

So the idea of a "stable" approach has been a very successful story with the airlines and, like a lot of things, it's percolated down to corporate flight departments and now the FAA is trying to put it into the conversation with general aviation pilots.

You're probably reading this and laughing that it's overkill for GA. Hot dogging a taildragger to the runway with all of that rudder and no flaps is fun! Right? I think it is! But what's best for a student? Or for an instrument rated pilot who regularly flies to instrument procedure minimums in more stressful conditions? Isn't it reasonable to discuss what is optimum for even us each time we fly? There are things that might be fun to do but we shouldn't necessarily accept the need to do them in each and every approach. We should be able to recognize when we're out of our own safety zones and recognize that a good go-around is a better decision than a bad landing and that a good landing begins earlier than the flare. Maybe the FAA will come up with standards that could be applied in some reasonable way to GA planes, maybe just having this conversation will encourage a few of you to think about how good landings and well executed approaches to the runway seem to go hand in hand. We should certainly be having this conversation with students so that it's baked into their pilot mindset from the beginning.

Sorry for the thread drift @BrianW !!! 😬😬😬
 
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Yes, but two mile final approach legs? We now have an unofficial "tight" pattern the tower offers: three touch and goes in a Decathlon or Cub for every flight school Cherokee approach.

I know what a stabilized approach is in a 737 or an A-320. What does a stabilized approach look like in a Citabria? Do all DPEs know what it is? Is it, say, a three degree glide slope at 70 mph? Does it vary with weight? With headwind/gust?

Shoot, I don't even have a definition of short approach - the local schools ask for them all the time, and then go a mile east of the threshold for a base leg.
 
IMO useful to differentiate into power off and power on approaches.

A power on approach is flown with constant glide slope, descent rate, and airspeed in landing configuration. Performance is controlled by adding or reducing power. I can't do those very well, but I assume you heavy guys are experts at this.

A power off approach is flown so that at any point in the approach, loss of power would result in making the airfield. Performance is controlled by adding or reducing drag by means of flaps or slips.

I always do power off. I fly to the key point abeam the numbers, cut power to idle, and glide to landing. If I have to add power then I did it wrong. Every landing is a practice emergency landing.

Obviously that is not suitable for the big iron that you guys fly. I makes sense that pilots in training to fly the big iron would practice power on stabilized approaches right from the start, and I see why the FAA might want pilots to demonstrate that skill in their checkrides. But I'm glad I don't have to do 'em.
 
Moved this to a new thread :)

@Bob Turner try this.....brief your student that they have to plane their descent to be 200 ft above the runway, at idle, with only enough crab or slip for the crosswind that is present. They can't have extra slip to correct a high position on final and they have to be at or near a fixed position on the runway. Don't tell them about the landings but see if their landings are any better if they nail their position on final by the 200' AGL mark. See if being "stable" for that last 200 ft before the flare helps them to produce a nicer roundout, flare and touchdown in a more predictable point on the runway.

@Big Ed turbojet aircraft land with a lot of drag partly because it helps make lift and it lowers landing speeds but it's also so our engines can stay spooled up in the event of a go around. the effect isn't as pronounced with modern jet engines but back in the day it would take a long time for a turbojet to spool up.

A stable approach in a light GA plane isn't the same thing as what the airlines are aiming for but you can take the concept, adapt it and probably be a safer pilot. Like the example above, see how well you can do to be at a set configuration and speed passing through 200 ft AGL or if that's too high, shoot for 100 ft and see how consistently you can nail a certain planned configuration at a certain point in the landing pattern and see if your landings get any better.
 
Big Ed said:
A power off approach is flown so that at any point in the approach, loss of power would result in making the airfield.
Click to expand...

That's the basis of every landing I've ever taught, if you are in the pattern and at any time losing the engine would prevent you from making the runway, you f'd up. I teach partial power until the runway is made at which point you go to idle, adjust your pitch to maintain your target airspeed, and glide to a nice landing or go around. Being high on final is better than being low but, in the world of teaching the idea of a "stable" approach, maybe the target for a student should be, if you're high to make the correction earlier so as to be passing 200' AGL on speed and on the desired glide path (whatever that is for your airplane) so no further correction is necessary. I'll have to try it myself and see how it changes things.
 
I'm with Bob on this. Teach them how to fly. Teach them Basic Skills. Teach them Energy Management on landing. If they continue their pursuit they can learn stabilized approaches during Instrument training. Then go drive the big aluminum tubes.

Can you imagine WWII trainees relying on stabilized approaches? LOL
 
I agree with you Sully. Teach them how to FLY. Everything else will fall into place. I flew with all the services and all of the corporate guys. The ones that knew how to fly would “water your eyes” every time.
They were one with the A/C. It was awesome!!
 
But Bart is agreeing with us, and using "stabilized" to describe a power off approach with a 200' final.

My point was, unless you agree at the outset on a definition, a student will have no idea what you are talking about when you say "stabilized." In jets, it was Vref plus ten, plus half the headwind and all of the gust, on a 3 degree glide slope, with engines spooled up. Completely defined - no questions at checkride time.

So, let's have a few definitions - Ed, Bart, and I agree on teaching power off at the abeam point. Vso plus ten? Plus five?
 
I just realized I am not qualified to engage in this discussion, so I will retract my opinions!
 
I use the same skillset to fly the Citabria that I flew the Boeing with... It's a whole lot easier to fly the Citabria procedure wise.. Alot tougher to fly it well though.. Think, Xwind, takeoff ,landing ,etc.. Course I'm my own worst critic...
 
Interesting article regarding training deaths during WWII.
www.realclearhistory.com

Sobering Stats: 15,000 U.S. Airmen Killed in Training in WW II

World War II was immense. So many numbers boggle the mind. Every day from Sept. 1, 1939-Aug. 14, 1945, 27,000 people were killed. That’s nine 9/11s every day for six years. Nearly 14 million Ame
www.realclearhistory.com www.realclearhistory.com

I'm just curious, let's try a little something something, try to fly your approach and make all of your adjustments so that by 200 ft AGL you are centered on the runway and in a position to glide to the touchdown zone without having to add power and without having to slip to lose altitude. Before the 200 ft point, do whatever you might normally do but try to be stable by 200 ft. Once you're doing that consistently, look back and assess if you are feeling more relaxed and ahead of the airplane in the flare and if you are touching down closer to what you would consider the touchdown zone for your runway.

This is the CFI Break Room after all so it's good to discuss this sort of stuff. When you're green, you grow. When you're ripe, you rot. Nobody ever got better at anything by thinking they had nothing left to learn, right?
 
Most of the time I fulfill all your requirements. I personally would not call that a stabilized approach. Neither, apparently, does at least one of our DPEs.
 
I just completed my CFI recertification training (American Flyers) for the umpteenth time and had some material from the class that was still handy to throw out for discussion. The FAA's textbook answer for a stabilized approach for piston aircraft is described in: Airplane Flying Handbook Chapter 9: Approaches and Landings


An excerpt from this link:

Pilots may consider the following elements when attempting to set up and fly a stabilized approach to landing. The pilot should focus
on the elements that lead to a stabilized approach rather than the order of the elements or the insistence on meeting all of the approach
criteria. For a typical piston aircraft, an approach is stabilized when the following criteria are met:
  1. Glide path. Typically a constant 3 degrees to the touchdown zone on the runway (obstructions permitting).
  2. Heading. The aircraft tracks the centerline to the runway with only minor heading/pitch changes necessary to correct for wind
    or turbulence to maintain alignment. Bank angle normally limited to 15 degrees once established on final.
  3. Airspeed. The aircraft speed is within +10 /-5 KIAS of the recommended landing speed specified in the AFM, 1.3VSO, or on approved placards/markings. If the pilot applies a gust factor, indicated airspeed should not decay below the recommended landing speed.
  4. Configuration. The aircraft is in the correct landing configuration with flaps as required; landing gear extended, and is in trim.
  5. Descent rate. A descent rate (generally 500-1000 fpm for light general aviation aircraft) makes for a safe approach. Minimal adjustments to the descent rate as the airplane approaches the runway provide an additional indication of a stabilized and safe approach. If using a descent rate in excess of 500 fpm due to approach considerations, the pilot should reduce the descent rate prior to 300 ft AGL.
  6. Power setting. The pilot should use a power setting appropriate for the aircraft configuration and not below the minimum power for approach as defined by the AFM.
  7. Briefings and checklists. Completing all briefings and checklists prior to initiating the approach (except the landing checklist), ensures the pilot can focus on the elements listed above.
 
They forgot to add - touchdown on the 1000 foot marker.
That is a far stretch from a power off abeam approach, except for the 1.3 Vso.
Did they have a definition of a short approach for you?
 
FlyingJ that's straight outta the SWA training manual. Prolly a copy of the FAA circular you posted. Just saying. Bob, I did some spot landings in the Citabria last week. Power off abeam the runway, tried not to come in on the power, used slips and flaps to land on the runway. Eye opening to say the least.
 
But essential. Fly like you think the engine will quit - stay high until you can get it down safely with the prop stopped.

Opinion.

I just came back from a model RR forum - makes me happy to come here and see how nice we treat each other - those folks are ready to shoot libtards. I always thought of model train nuts as one step away from dollhouse collectors - harmless - but they are going to be on the front lines, armed to the teeth. Scary.

Darrell - I practice turnbacks every chance I get. I get a clearance, chop the power to idle, simulate a delay time, then see if I can make it back to the airport environment. I don't do it with the Decathlon, since I "baby" that engine, but I routinely do it in the Cubs and Stearman. The parameters are critically important - lenght of runway, wind, altitude and geographic point of simulated failure, etc. - When acting as instructor, I ask regularly "where would you go if it quit?" Always have a plan.
 
Me and my hangar mate always have that conversation. He has a 185 & is a crop duster. There’s a road next to the strip. I think that’s where we’d put it down. There’s a bunch of cleared land too but the hogs have it so rooted up that I guarantee your gonna nose it over.
 
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