Fear and Loathing in Base to Final

[drseti]

Instructor comments?

The advantage of dropping the nose in a pattern turn is that it improves visibility. The drawback is that your airspeed is wandering. It's probably easier to stay on the glidepath if you do a stabilized pattern (constant airspeed from downwind to the flare). In the SportStar, the magic number for this is 60 kts (which is close to both 1.3 x Vso and to best glide speed). This number should work for most any LSA, since they are all restricted to the same max stall speed (45 kts), and multiplying that by 1.3 gets you pretty close to 60.

Other planes will have different sweet spots, but there's likely to be an optimum approach and pattern speed for whatever plane you're flying. Do talk to your instructor about this, because there are certainly exceptions (gusty winds, crosswind landings, obstacle approaches, and short/soft field operations come to mind). But, if you learn to fly the pattern at a constant speed, that's one less variable to worry about when you're perfecting the flare.

[designrs]

The advantage of dropping the nose in a pattern turn is that it improves visibility. The drawback is that your airspeed is wandering.

I'm flying PiperSport with similar pattern and glide speeds... 65kts/60kts. Don't find dipping the nose in turning to base and final to gain airspeed, usually it just helps maintain constant airspeed, and if there is some distraction I'd rather be gaining a few knots than loosing them. My instructor approves.

[drseti]

My instructor approves.

In that case, how could I possibly disapprove?

[designrs]

put that plane into a 60 degree bank, with enough back pressure to hold altitude, and your load factor now increases to 2. This increases the stall speed significantly, so if you entered the turn in level flight at 60 knots, you just stalled!

I think the reason for many of the fatal stall/spin accidents on the base to final turn is that pilots overshoot, then overbank trying to get back on the centerline, and then haul back on the stick when they find themselves low. A bad situation to get oneself in.

Great comment drseti.
It is enlightening to read the reasons why some accident patterns sadly happen over and over again. This comment should be on the "20 Things to know list to reduce risk and increase safety"

[jnmeade]

Instructor comments?

But, if you learn to fly the pattern at a constant speed, that's one less variable to worry about when you're perfecting the flare.

Are you saying fly the entire pattern at one speed? I've never heard that recommended.

[jnmeade]

A couple of ideas.
1. Avoid "square" corners in the pattern. Glider pilots and carrier pilots don't fly square corners. Even if you don't fly a semi-circle, at least round out the corners. It avoids the abrupt transition between straight and level and steep turns and back again. It lets you keep an eye on the runway end and better judge whether your turns are steep enough. Do keep an eye out to the guy on long final.
2. Know the wind. Knowing the wind informs you as to how tight you should keep the pattern. A strong wind means you'll turn base sooner so the wind doesn't blow you away. It will tell you how much and which direction to crab so you don't get blown away. A strong wind from some directions may cause you to start turns a little sooner.
3. Stablize the plane on downwind. Try to only change one parameter at a time.

The end result of this is to keep you out of the situation where you look up and find you are overflying final, are already steep, and maybe are low. These set up the cross control stall as has been discussed.

I don't think the CTSW is cleared for cross control stalls because it would exceed the pitch limitation. One two occassions, I tood students who would not pay attention in the pattern out in a C-150 and demonstrated to them what would happen if they got into a cross control stall. I promise you, neither ever got behind in the pattern again. A cross control stall can be quite abrupt and although you are not, you would swear that one second you are flying along and the next you are looking straight down. Recovering from a cross control stall at base-final altitude would be a real challenge even if you were ready for it. I would not bet that most could do so.

[drseti]

I've never heard that recommended.

I know it's unconventional (like much of my curriculum). But there are some definite advantages to reducing the number of variables. Here's the routine I teach:

I have my students complete a pre-landing checklist and establish slow flight on downwind, 1000 AGL, 1/2 mile or so from the runway. (In the SportStar, that's left tank, fuel pump on, monitor ATIS, set 4000 RPM. Slow down inside the white arc, set flaps 15, trim for level flight, and you'll find yourself stabilized at 60 kts). You can fine-tune airspeed with elevator, altitude with power.

Abeam the numbers, my students close the throttle and glide, still at 60 kts. (Carb heat on if relative humidity is high and temp/dewpoint spread is narrow). The plane will try to nose down and accelerate a bit, so they may need some back pressure on the stick to hold 60 kts -- but, they're maintaining that speed primarily by monitoring pitch angle, only cross-checking the airspeed indicator occasionally.

While rolling onto base, I have the students set flaps 30. In this plane, the extra drag just about compensates for the effects of the back-pressure being held following the power reduction. In other words, by adding flap, relaxing stick pressure, and doing nothing else, the plane will continue to glide at 60 kts, pretty much hands-off. No re-trimming required.

If all this is done correctly, and absent any adverse winds, you end up turning final about 500 AGL and 1/2 mile from the threshold. Once lined up, assess the glidepath. If on target, just keep gliding at 60 kts, flare over the threshold, and land. If high or landing long, you still have another notch of flaps available. If low or landing short, one can always bring the power back in.

If really low, or not lined up properly, or airspeed not stabilized, or anything else not perfect, just go around and try again. Since you've been gliding at (and are already trimmed for) 60 knots, which is normal climbout speed, the go-around requires merely easing in full power, compensating for torque with right rudder as required, and holding the speed at 60 on the climbout, with elevator pressures as necessary. Once established in the climb, one can bleed off the flaps gradually, a notch at a time.

The nice thing about doing constant-airspeed glider landings is that, if the student ever has an engine failure requiring a for-real emergency landing, it becomes a non-event (you've already done this a hundred times).

I've been teaching pattern work this way for a couple of years now. It doesn't work for everyone, and isn't always the right technique (short field, soft field, obstructed, cross-wind, or gusty wind landings require tricks of their own), but it's a good place to start.

Students, try this sometime (only, discuss it with your instructor first).

[ussyorktown]

thanks for all the advise. When my FAA inspector gave me my check ride he asked me why I was interested in flying?
I said, "I'm a lawyer and I'm sick of the bullshit. There's no bullshit in flying."
You can't bullshit Mother Nature or the laws of physics. Either you do it right or you die. As a lawyer I hate it when a judge ignores a law to come out with the result he wants.
That doesn't happen in flying.
Either figure out the right way, do it right or die."
You can't ignore the rules set down by Mother Nature or the Laws of Physics!

[drseti]

You can't ignore the rules set down by Mother Nature or the Laws of Physics!

Or, as Mr. Scott often told James T. Kirk, "Captain, I canna' change the laws of physics!"

[jnmeade]

I've never heard that recommended.

I know it's unconventional (like much of my curriculum). But there are some definite advantages to reducing the number of variables. .

I agree wholeheartedly with reducing the number of variables, but I do it a different way. I change one thing at a time. The FAA teaches a stabilized approach, but they don't mean an unchanging approach.

I will admit that I've been on rides in a Citation where we set 60% power at 30,000 feet and never touched a throttle all the way to the threshhold, but we were constantly changing pitch and airspeed.

Here is an observation I've made after a lot of years. I wish I'd known it earlier.

The Law Of Primacy is powerful. It is a great aid. I used to unwittingly use it as a crutch. That is, I'd get the student into a routine that is so controlled that the student is uncomfortable when outside that envirionment. This is the source of some great arguments about pattern entry, for example.

Like many, I did most of my CFI work before I started flying much real weather, multi-engine and charter. Sometimes I shudder at the correct and well meaning but not really appropriate things I'd teach. I sent students to their checkride almost always under 50 hours, sometimes getting their 40 on the way to the ride. Every one passed. But, I'm afraid I turned out people who were very good in a defined setting. Now, I'd take another 5-10 hours and broaden some aspects of their training to show them how the bigger world works.

We'll have to disagree on the pattern work. I like to see it in a broader context. I don't doubt your approach works well.

[jnmeade]

thanks for all the advise. When my FAA inspector gave me my check ride he asked me why I was interested in flying?
I said, "I'm a lawyer and I'm sick of the bull

well, at the risk of being unpopular and considered a prude, I like it better when people use language that isn't quite so strong. As a farmer, I'm surrounded by the substance but prefer to consider it fertilizer.

[ussyorktown]

OK, i'll take your advise. Everytime I do a hard landing I'll yell out FERTILIZER!

[drseti]

Sometimes I shudder at the correct and well meaning but not really appropriate things I'd teach.

Hey, we all have cause to shudder, looking back on our early teaching experiences. The nice thing about instructing is that it gives us such a great opportunity to learn!

[drseti]

1. Avoid "square" corners in the pattern. <snip>
2. Know the wind. <snip>
3. Stablize the plane on downwind.

Bravo to all three recommendations!

[FastEddieB]

We recently had a Cirrus spin out of a base to final turn, and I began a thread on the Cirrus Owners and Pilots Ass'n site titled "Bank Is Not The Enemy" in response to what I thought was some bad info/advice in the thread:

I thought this was important enough to post on its own so as not to possibly get buried in one of the several threads already going about problems in the pattern.

It appears that many of the posts either directly or indirectly imply excessive bank as a factor in stall/spin accidents. One poster said not to bank more than xº, and another suggested to avoid any bank in the pattern at all - to fly straight in approaches - and that when a pattern is unavoidable, to fly a wide one, supposedly to keep bank angles shallow.

I think this is to focus on the wrong thing. As I said in one of the threads, the stall/spins usually result from too little bank, not too much. If a pilot smoothly rolls into a coordinated bank of even 45º or more and pulls too hard, he’ll get a buffet and the nose will pitch away from him if allowed to progress to a full stall. It will only spin if there’s too little bank and the pilot is skidding the plane around the turn with rudder.

We’ve all done steep turns. The commercial pilots among us have all done them to 60º of bank, and have also done them in steep spirals, also with up to 60º of bank. I’ll ask this question without knowing the answer, but suspecting it: “How many of you have spun out of a 60º steep turn or steep spiral?” I’ve done a whole bunch, both alone and with students and don’t recall coming close.

Think back to accelerated stalls. Here a spin is more likely, especially if the turn is not coordinated. But remember how much pull is required to actually get that buffet once the bank is established. Pretty hard to do accidentally.

One misconception is that by using less bank we’re farther from a spin. But if there’s spin input in the pattern, it matters little if it occurs at 15º or 45º of bank - either way the plane may end up nearly inverted and pointing at the ground. IOW, I don’t think shallower bank angles give any protection once a cross-controlled situation is allowed to develop. This image from Stick and Rudder shows no unusual bank right before spinning in:



There was also the suggestion made to never “pull” when making turns in the pattern. I understand the motivation, but find this simplistic advice. My experience is that in a properly trimmed plane every turn in the pattern calls for some pull - otherwise the nose will fall and speed will build. The admonition should be to not pull too hard, not to not pull at all.

If I’m evaluating a pilot and I routinely see him banking to 45º or so in the pattern, he’ll earn a mild comment from me, something like, “You know, that’s a bit much on the bank there - maybe plan ahead and lead your turns a bit more and you won’t need quite so much”. OTOH, if a pilot seems fearful of banking in the pattern and is subtly or not-so-subtly “cheating” with rudder, he’ll get a far sterner reprimand.

Let me also point out that wide patterns and limited bank have their own dangers. You’re farther from the airport if something goes wrong. You’re in a position where other pilots might not be looking for you. You’re blind for a longer time in either in the direction of the turn or in the direction of the raised wing, depending on if you’re high- or low-winged. A straight-in approach holds the increased danger of a low-wing aircraft descending onto a high-wing aircraft, each in the other's blind spot for an extended period.There are times to “think outside the box”, but traffic patterns have held us in good stead for a long time and we should think long and hard before giving them up.

So, what’s my advice? Get rid of the idea that banking in and of itself holds any danger - bank as much as is needed for the turn you need to make. If the turn needed is too tight and would require too much bank, roll out, climb, advise and come back and try again. If you’re a private pilot and have never done 60º steep turns or 60º steep spirals, seek out an instructor and learn to get comfortable with them. If you’re a commercial pilot who may be rusty, go out and practice them either with or without an instructor (but with a safety pilot).

But get it out of your head that there’s anything “wrong” with bank - there’s not.