Approaching Much Too Fast

[shimmydampner]

A light C-172 can be landed in about 150 feet or the width of 08R at YVR.

Heck, much bigger airplanes than a 172 can do better than that.
http://m.youtube.com/watch?v=JwMlgc1saHs

[Nwtflier]

I'd like to see the takeoff out of there.

[PilotDAR]

What approach speed would you recommend in a fifty knot wind ?

Same, though I might add a factor if it were gusty.

What approach speed would you recommend in a fifty knot cross wind

The speed I thought most appropriate to approach on a different runway!

Like many planes, a single Cessna will "talk to you" on final, and let you know the proper speed. Fixating on the ASI indication might actually distract you from feeling what the plane is trying to tell you.

In flight testing the rather modified C182 amphibian (while going forward), I was learning new speeds, as there are none published for a plane with all these mods on it. At 3350 pounds gross weight (400 pounds more that original), it was a bit of effort, until I found the secret: I pulled the stall warning CB, and ignored the ASIs, until I had the feel.

After some practice, I found that I was comfortably off the runway at 55 KIAS, and off the water at 50KIAS. For approach 75 KIAS, to 70 short final, slowing to 60 in the flare is comfortable. The plane told me the speeds - no books involved. For reference, at 3350 pounds, forward C of G, idle, full flaps stall speed: 38 KIAS, and power 25 square stall speed: 31 KIAS (with a suspected position error there).

Feel what the plane wants....

[shimmydampner]

What approach speed would you recommend in a fifty knot cross wind

Since when does wind direction factor into approach speed? I've never understood the false sense of security some get by carrying extra speed in a crosswind. It just leads to that nasty floating tendency talked about earlier and makes for some spectacular displays of wrestling while the wind has all that extra time to push things off centreline and cant longitudinal axes away from straight.

Like many planes, a single Cessna will "talk to you"

Couldn't agree more. Learning to understand, however, takes time and is becoming something of a lost art as the early drive for airline prep seems to focus on reliance on numbers, checklists and SOPs, in my opinion.

[Colonel Sanders]

Learning to understand, however, takes time and is becoming something of a lost art as the early drive for airline prep seems to focus on reliance on numbers, checklists and SOPs, in my opinion.

Agreed, but not everyone is going to be an airline
pilot. Despite that, everyone wants to wear a white
shirt, wear four gold bars, and have a checklist four
inches thick to fly a buck fifty

And, it's really not hard to learn that

Attitude + Power = Performance

a lesson that Air France seemed to struggle with.

A while back, a student was going for his PPL. Bright
guy. His regular instructor was away on vacation,
and he asked me to go up in the 172 with him, which
he quite possibly now regrets.

I walked out to the 172 with my paperwork. Everyone
knows that paperwork is the most important aspect of
aviation. My paperwork consisted of two blank 8.5x11
pieces of paper, which I proceeded to cover his side of
the dash with. Pushed it over the knobs and stuff sticking
out, it stayed there quite nicely.

He had a tach, and a ball, and not much else. He started
up, did the runup, taxiied out and took off.

No airspeed indicator, no altimeter, nothing. I told him
to put the nose where it usually was, and the power where
it usually was.

Miraculously, the airplane flew. Without a single white shirt
or even one gold bar in sight.

We levelled off at around 3000 AGL and I had him do slow
flight. With no instruments. Just the stall horn.

Then some steep turns.

Then, we went back to the airport, joined the downwind,
and landed. He was a little fast on final (nose was down)
but I didn't bug him - we had 4000 feet of pavement, and
it worked out ok.

And no instruments at all, for the entire flight. He could
look outside, and set the power. And that worked pretty
well.

One lesson. Not sure that's really a "lost art", but ok.

However, you might be right if you assumed that the
young instructors didn't want to do this kind of training.

[LousyFisherman]

The one advantage I have found in approaching too fast is it provides the opportunity for practicing delicate control movements while floating down the runway maintaining proper position and alignment. The C150 at 65-70 is extremely difficult to land properly, at 50-55 it's tame. At least for me

I never refer to calibrated air speed, but then I do not believe the ASI when it is below 50 either.

Question about stabilized approaches though. If I am high, I enter a forward slip and when I exit the slip I always have gained 10 mph or so. I assume this is due to the fear of stalling in the slip but I have yet to catch myself conciously pushing the stick forward. Since I am 10 mph fast I exit the slip low and drop speed as I regain the approach path. How long before touchdown should this maneuver be completed?

And thanks to your opinions I fly nice tight circuits now. Which has caused me to have trouble flying a consistent approach when behind students flying huge circuits.

Off to Kelowna this week

LF

[Colonel Sanders]

I fly nice tight circuits now

Our work here is done, Tonto.

[Beefitarian]

A light C-172 can be landed in about 150 feet or the width of 08R at YVR.

Heck, much bigger airplanes than a 172 can do better than that.

Wow, now that's a full stop.

[photofly]

What approach speed would you recommend in a fifty knot cross wind

Since when does wind direction factor into approach speed? I've never understood the false sense of security some get by carrying extra speed in a crosswind.

There's a good (aerodynamic) reason why you might want extra airspeed in a strong crosswind. Start by asking yourself what is the aerodynamic difference between a forward slip to lose altitude and the sideslip you might use to land in a strong crosswind, particularly a crosswind strong enough to require full rudder input to keep the nose aligned with the runway.

[shimmydampner]

You sideslip your entire final in crosswinds requiring full rudder?

[photofly]

Let's stick to the few seconds before touch-down where you transition from a crab to a sideslip, whenever you choose to do it. What's the aerodynamic difference between a forward slip to lose height, and a sideslip to put the nose straight, a few seconds before touchdown in a crosswind strong enough to need full rudder?

So there you are, on final approach in a 20 knot crosswind, crabbed into the wind with your regular approach airspeed of 1.3Vs0 (or 1.3Vs1, if you're flaps up because of the wind) plus 5 extra knots that you typically lose close to the threshold, descending at the usual 500fpm. Now you decide on short-ish final to transition from crabbed flight to a sideslip to get the measure of the winds and gauge whether you have enough rudder authority.

As it happens, you have just about enough rudder authority at that speed, but not much margin. Full, or nearly full rudder is needed to get the nose straight, and quite a significant aileron input is needed to arrest the sideways drift.

What happens to your rate of descent as you enter the sideslip? And what are you going to do about it?

[shimmydampner]

As has already been pointed out, by then I don't care what the ASl says. And I don't use less flap due to a crosswind.
I get the feeling our frames of reference are very different.

[photofly]

Work with me on this. This has nothing to do with whether you look at the ASI, or don't look at the ASI.

Whether you use flap or not - what happens to your rate of descent when you enter a full-rudder sideslip? And what do you do about it?

I'm open to suggestions from anyone else, too.

[PilotDAR]

I don't care what the ASl says. And I don't use less flap due to a crosswind.

I fully agree.

Whether you use flap or not - what happens to your rate of descent when you enter a full-rudder sideslip? And what do you do about it?

From my recollection of doing this many times, I don't care about a possible effect upon my rate of descent at that point, 'cause I just entered ground effect, and touched down the upwind main wheel, before I drifted across the runway. Without the excess speed to dissipate, I could get that wheel on, and the other shorty thereafter, and then just steer.

It is not often that I got out looking for a crosswind, but there have been times. I do recall just about every Flight Manual providing me a "demonstrated crosswind" value, and often making reference to a lesser flap setting for crosswind landings, but I don't recall ever reading a Flight Manual instruction to fly a faster approach in a crosswind. So I don't, unless gusty conditions dictate, and that's unrelated to crosswinds specifically.

I did do crosswind testing of a highly modified Cessna Grand Caravan, having searched out a runway with the required 25 knot direct crosswind (in gusts). Though it required diligent control use, I flew book speeds with no problem. I did not use full rudder during approach, but did at touchdown and rollout. During six such landings, I had no problem.

I accept that there could be slight changes in the theoretical ideal approach speed with the use of controls during a crosswind approach, but that is accounted for in the design speed margins for the aircraft. 1.3 Vs to 1.1 Vs is a margin, and you still do have full control of the aircraft available at 1.1 Vs, just best very close to the runway while using it!

[spaner]

Good dis of late, with no dissing, nice

What really you're talking about is a 3 second window, should be no more than that.
Why don't you consider it from a full rudder deflection, and then you can interpolate the variables.
Carrying more speed to 1.3 will lengthen the time to touchdown 5 seconds, initiate drift, and lengthen the landing. Mass is a greater consideration over an increase in speed, Delta-S. Inertia, although the energy carried is 1/2 mv^2, it's the change in speed that you can control and not the mass. The difference is that you want a 152 to transition in 2 seconds, to avoid drift. A 737 will transition over 5 seconds, and will not begin to drift for 7 seconds.
More speed, in a lighter ac, just means that you will drift, and are more prone to upside wing strike.
An increase in speed is only recommended during gusts (gust factor) so that control is not lost during a performance loss condition.
Less flap will reduce the wing loading, and open the envelop for the gusting condition. This will also allow you to carry more speed, will not increase the touchdown time 3 seconds (1.1vf2 vs 1.1vf0), but will increase the landing distance. Rudder effectiveness will also increase with the higher speed.
The opposite is true, and the rudder becomes less effective to transition quickly. (nose swing) Also, as above, the performance envelope is tighter with the higher flap setting and wing loading.
A small gust will lift a light ac easily at (f2), and the loss of the gust will drop it.
Use both, or neither for gust. Just crosswinds, then not at all. 1.1f2
It's easier to get the hands and feet for this than it is to pick it apart logically. Just go do it.

Just my opinion, it's nice to read others' without the bashing.

[photofly]

From my recollection of doing this many times, I don't care about a possible effect upon my rate of descent at that point, 'cause I just entered ground effect

So no increase in airspeed is helpful if you plan to kick out the crab only once you're in ground effect. I'd tend to agree.

Everyone who likes to transition to a sideslip somewhat earlier in the approach however, will recognize the extra sink rate they get when they do so.

If the strong crosswind extends all the way to the ground then landing in a slip a little fast is no issue. There's no float, because the effect of the maintained sideslip is to increase your descent rate. And there's no chance of a flat landing, because holding the downwind wheel off the ground automatically keeps the nosewheel in the air.

If, however, like it often does, the crosswind drops off significantly very close to the ground, then you are going to be in trouble.

[Beefitarian]

I has a question.
How does everyone approach a small place with no wind reports? You know there is cross wind because the sock it changing around but mostly indicating a wind fromthe side.

Can you tell if it's gusty or would anyone add 5-10 knots? Providing you have lot's of runway length.

Just my opinion, it's nice to read others' without the bashing.

Plus cheezeburger!

[Colonel Sanders]

because the sock is changing

IMHO people place 'WAY too much importance
to the windsock - or the ATIS, for that matter,
which might be almost an hour old.

At my airport, the previous manager went bananas
and installed three windsocks on a rather short
4000 foot runway. I can understand if it was 12,000
feet long, but ...

Frequently, all three windsocks are indicating completely
different wind directions, strengths, and gusts. Sometimes
because there is an odd number of windsocks, you can
"vote" and the majority wins

But after a while, you stop giving a sh1t what the wind
reports and windsock is. It's gonna do, what it's gonna
do, and your job is to manipulate the flight and engine
controls to make the airplane do what you want.

I honestly couldn't give a sh1t what the crosswind component
or gust is. Stick over - which most people don't do.

I couldn't really care less what the tailwind component
is, either. People in light trainers freak out when they have
1 or 2 knots of tailwind component. The irony that they
are approaching 10 knots too fast goes 'way, 'way over
their heads.

I couldn't give a sh1t about a 20 knot tailwind component
in a 172. With 60 knots on final, that's 80 knots over the
ground. On the same 4000 feet of runway, I fly jets with
125 knots short final speed in the manual.

Keep in mind that kinetic energy is a function of velocity
SQUARED. If I am happy taking well over 100 knots of
groundspeed, why would I be reluctant to take 80 knots
of groundspeed?!

Once again - we are NOT dealing with limitations of the
aircraft, or the facilities (horrendously, excessively long
runways for the category of aircraft).

The limitations here are solely that of the pilot, which I
would find extremely embarrassing if that was the case
for me. I would do something about it.

[Beefitarian]

Cool, thanks.

At my level the sock is way more interesting than atis. Both are just tools. They are great but like so many other terrific options available in airplanes, they can be misused easily.

It's not that you never use an airspeed indicator in my opinion. The key is you don't fixate on it, letting other equally important or in some cases more important items slip away. Amirite?

I would do something about it.

I'm working on it.

[triplese7en]

It seems that folks do not consider that the energy they are carrying on approach is a combination of both height and speed that must be dissipated

I would actually say airspeed and vertical speed—not height. Descending at a high rate will require a decent pull on the elevator and will increase drag quite a bit. Sometimes descending steeply (just over 3 degrees) and on speed will produce very nice conditions for landing. The flair will bleed most of the speed and you'll only require a slight decrease of power and you'll plop right down where you wanted.

As for all these speeds that everyone is talking about, generally when the POH says "approach speed" they mean Vref (1.3 Vs1) which is the speed to be at when 50 feet above the threshold (usually on a 3 degree path). Touchdown speed should be closer to 1.05-1.1Vs1. The other consideration is that the Vs1 speed is power off. When you're approaching with power on the actual stall speed will be slightly lower. That's not something I would really discuss with a PPL student when learning to land though.

[Colonel Sanders]

I would actually say airspeed and vertical speed—not height

No. Not sure of your physics background, but for simplicity
consider a glider (disregard the engine right now).

The total energy of the glider Et can be written as:

Et = Ep + Ek

where Ep = mgh represents the potential energy
of the aircraft due to it's height, and

Ek = 1/2 m v^^2 represents the kinetic energy
of the aircraft due to it's speed.

Substituting for Ep and Ek:

Et = mgh + 1/2 mv^^2

you can see that the only terms that we can vary
in Et are:

mass of the airplane
height of the airplane
speed of the airplane

We cannot do much about earth's mass which
determines g which is 9.8 m/sec^^2 or 32 ft/sec^^2

Anyone that actually graduated high school was
required to learn this material, perhaps in grade 10?

[Beefitarian]

Sorry I'm a giant ignoramus but what's mgh, mean glider height?

You did not need to take physics or much math to get a diploma back when I was trying to get out of high school in Alberta.

I like a nice steep approach too because I can bring the engine to idle and don't have to care about it failing, provided I set up a good gliding approach. The biggest problem for me is not staying current enough by flying everyday so I am not skilled enough to land on the numbers every time.

[spaner]

You probably think he meant MPH, from a light single IAS right? Part of that's my fault (slap face)
Not your fault but we're getting into the high performance associated with a type cert.
Better to just go out and teach the hands and feet, the brain will come if you get into something bigger and faster. He's got it all laid out there though, and negating the energy dissipation side of the equation, you do have to consider Ep as well as Ek, where,

Ek=the kinetic energy
Ep=the potential energy

Ep=MGH=MASS*GRAVITY*HEIGHT

This is how simulators work, and why computers can fly planes...math

edit, it's WAY more important as a ppl, to consider deck angle (f2 vs f0), seat height, and crab angle, during the transition. I know some guys mentioned cross-control in the slide..I can't comment on that except to say that I don't recommend it. It teaches a bad habit to cheat the turn to final with a skid or slip, add a gust, and a strong base leg tail wind, stall-spin-crash.

[New_PIC]

Sorry I'm a giant ignoramus but what's mgh, mean glider height?

You did not need to take physics or much math to get a diploma back when I was trying to get out of high school in Alberta.

I like a nice steep approach too because I can bring the engine to idle and don't have to care about it failing, provided I set up a good gliding approach. The biggest problem for me is not staying current enough by flying everyday so I am not skilled enough to land on the numbers every time.

My read of mgh would be mass * gravity * height, or potential energy. Maybe the comment about rate of descent was considering vertical inertia? Just guessing...
edit: typing too slow!

[Beefitarian]

Cool thanks.