Why are we taught to land differently 91 vs 121

[phoenix 23684]

So I was reading one of the responses to another tread about someone looking for help with their landing, why are we taught different techniques when landing a 172 vs an airliner.

Let me clarify, I know most of us have been taught to land a C-172, during our PPL, in such a way as to touch down ideally at the slowest speed or just as the horn comes on. Yet we move into part 121/135 and no longer the case, we just fly the profile and arrest the descent. When's the last time you'd seen a 747 hold it of the ground till the horn
My only theory comes from flying tail wheels; more specifically 3 point landings, where you just hold it of the ground at that attitude until it settles, basically the wings can no longer provide sufficient lift for at that angle and speed. Can this be just a residual of earlier school of thought when tails where the norms?
Yes, I have heard all the theories about why it's important to put it down as slow as possible and understand the dangers of trying to float an airliner, but really you could very well and perhaps easier to put/teach a light GA on the ground the same way we do it with the large ones, specially career students.

Thoughts?

On a side note has anyone flown a light GA after becoming an airline pilot, I have not yet, but I hear the first time it's scary specially on final due to the slower speed.

[BobDDuck]

I was never taught to land at just above stall speed in a 172 unless I was doing a soft field landing. But I know many people are. In reality, your forward speed doesn't matter up until a point, it's the downward speed you've got to watch. At some point, obviously, you would be going so fast that you would still be generating too much lift to land, but touching down at stall+15 in a Cessna isn't going to do that.

Also, I have flown some light GA stuff after being in the jet for a year or so. It's... interesting. The hardest thing for me was flying a normal pattern, as I tended to keep the pattern an extra mile or so out. The speed difference wasn't too bad, although there are a few moments when you wonder why you aren't falling out of the sky.

[Nick]

Holding a swept-wing jet off the runway while you try to bleed it down to stall speed is a good way to get an expensive tailstrike.

Normal approach speed for a jet airliner is called VAPP which is VREF plus any wind additive. VREF is normally 1.3 times VSO which is the stalling speed or "minimum steady flight speed" in the landing configuration. The landing flare is rather slight, really just to arrest the descent rate. The mains typically will touch down in a gentle descent as we are squeezing the power off to idle. You just don't do full-stall landings like you might in some light planes.

[SoCalAprch]

I don't really know. I know that swept wings don't like slow airspeeds and if you pull up at a slow airspeed you can increase your descent. Its probably just the difference in the way the planes are built and the different aerodynamic factors that come with bigger heavier planes.

Also could be the fact that airliners have different ref speeds for different conditions where a cessna you just go with the approach speed, maybe add a few knots for gust, and see what happens.

[Clocks]

I always learned in the 172 that you should hear the stall horn squawk just as the mains hit the pavement. In the seminole though it was more similar to the erj where you are approaching the runway with power in and basically as soon as you go to idle the airplane will settle very quickly (so you time it and bring the power back gradually with the last bit coming out close to the ground and flaring). I think if you tried to bring a 172 onto the runway with an equivalent amount of power you'd simply be going way to fast.

I don't know though, that's just how I interpreted things through training. I don't remember it being explained.

[Snuggle]

You can land the 1900 at stall speed with the stall horn going off just like a cessna.

[Matt13C]

Isn't that what the Jet Blue pilot did when his nose wheel was broken?


http://youtube.com/watch?v=FoMf7lTpWzU

[Nick]

Originally Posted by Matt13C

Isn't that what the Jet Blue pilot did when his nose wheel was broken?

The link didn't work (for me at least).

When they landed they touched down on the main landing gear the normal way. Maybe a little float but nothing like holding it off until stall.

Flying the nose down to the pavement slowly, which is what they did in that situation, is something that can be done on any landing. For example on the ERJ the yoke comes almost all the way back to slow the descent of the nosewheel so it doesn't come crashing down too hard.

[Minuteman]

Because 121 aircraft are certified under part 25, not part 23 (like most GA aircraft).

They are both still aircraft that both still fly for mostly the same reason, but the performance requirements are legislated separately, in parallel.

Besides, I'd eventually end up strangling guys "in the pattern" who were stabilized on final at 1000' feet and three miles out at 70 knots.

[Screaming_Emu]

Two words...stick pusher

[Maurus]

Airlines also don't usually fly into small strips that could be close to the landing distance. GA aircraft go into 2000ft and less runways all the time. Landing at a slower speed near stall will allow us to land in a shorter distance. Most jets usually wont have to worry about runway lengths so much unless they fly into places like Jackson Hole.

[jynxyjoe]

Originally Posted by Snuggle

You can land the 1900 at stall speed with the stall horn going off just like a cessna.

You can, and you shouldn't . I know u know better, just razing u.

[jynxyjoe]

Originally Posted by Minuteman

Because 121 aircraft are certified under part 25, not part 23 (like most GA aircraft).

They are both still aircraft that both still fly for mostly the same reason, but the performance requirements are legislated separately, in parallel.

Besides, I'd eventually end up strangling guys "in the pattern" who were stabilized on final at 1000' feet and three miles out at 70 knots.

I'd just cut in front of them with the old Super Viking.

Slow pokes!

[ppragman]

Originally Posted by phoenix 23684

So I was reading one of the responses to another tread about someone looking for help with their landing, why are we taught different techniques when landing a 172 vs an airliner.

Let me clarify, I know most of us have been taught to land a C-172, during our PPL, in such a way as to touch down ideally at the slowest speed or just as the horn comes on. Yet we move into part 121/135 and no longer the case, we just fly the profile and arrest the descent. When's the last time you'd seen a 747 hold it of the ground till the horn
My only theory comes from flying tail wheels; more specifically 3 point landings, where you just hold it of the ground at that attitude until it settles, basically the wings can no longer provide sufficient lift for at that angle and speed. Can this be just a residual of earlier school of thought when tails where the norms?
Yes, I have heard all the theories about why it's important to put it down as slow as possible and understand the dangers of trying to float an airliner, but really you could very well and perhaps easier to put/teach a light GA on the ground the same way we do it with the large ones, specially career students.

Thoughts?

On a side note has anyone flown a light GA after becoming an airline pilot, I have not yet, but I hear the first time it's scary specially on final due to the slower speed.

I think this is more of a twin vs. single question. You don't bring any twin in on the horn because if you lose an engine you're going to Vmc over and crash if you're not right on your toes. That being said however, my multi experience is not all that diverse, with the 1900C, the twinstar, and the seminole, I suppose if I flew some other equipment it might be different. A twin otter probably comes in right on the horn.

More than anything, speed is safer.

As for the tailwheel stuff, one of my buddies has some experience in the DC-3, and that is not an airplane you want to 3 point. Although it can be done, it puts a lot of stress on the airframe if done improperly.

[Matt13C]

Originally Posted by Nick

The link didn't work (for me at least).

When they landed they touched down on the main landing gear the normal way. Maybe a little float but nothing like holding it off until stall.

Flying the nose down to the pavement slowly, which is what they did in that situation, is something that can be done on any landing. For example on the ERJ the yoke comes almost all the way back to slow the descent of the nosewheel so it doesn't come crashing down too hard.

Yeah, it wont work for some reason. I guess my copy/paste skills need some work.

Thanks for the explanation though.

[mojo6911]

Seems pretty simple to me.

172 = Small piston trainer
Airliner = Airliner

Get it?

[BobDDuck]

Originally Posted by ppragman

I think this is more of a twin vs. single question. You don't bring any twin in on the horn because if you lose an engine you're going to Vmc over and crash if you're not right on your toes.

I get what you are saying, but you'd need power in for that to be an issue, and chances are, when landing, you aren't going to have power.

[SoCalAprch]

Thinking about it I think we are taught to land slow/stall the Cessnas on because the wings create so much lift at slow airspeeds the controllability on the ground decreases if you land to fast. I remember students landing fast and feeling like the wheels were touching but we were still flying. The wings continued to produce life while rolling down the runway and it kinda left you with a feeling of no control and hoping a xwind didn't gust or anything.

[Doug Taylor]

With every knot flown below Vref, your probability of a tail strike and "Breakfast With the Chief Pilot (and your ALPA rep)" are asymptotically approaching 100%

[kfour]

Originally Posted by ppragman

I think this is more of a twin vs. single question. You don't bring any twin in on the horn because if you lose an engine you're going to Vmc over and crash if you're not right on your toes.

I suppose...If i came in with full power and flared as the stall horn was going off. Who comes in to land with full power anyway?

[Nick]

Originally Posted by Screaming_Emu

Two words...stick pusher

Does the CRJ stick pusher actually kick in if you were in the flare and got that slow? That does not seem very desirable!

The ERJ pusher is disabled below 200' AGL.

[Rocketman99]

Originally Posted by Doug Taylor

asymptotically approaching 100%

Wow!!! Never expected someone to refer to asymptotes on a general JC thread, not even you Dough.

[Doug Taylor]

I'm a math and science geek, man!

[Screaming_Emu]

Originally Posted by Nick

Does the CRJ stick pusher actually kick in if you were in the flare and got that slow? That does not seem very desirable!

The ERJ pusher is disabled below 200' AGL.

Nope. Or if it is, they don't tell us about it in the POH.

Here is what they say the stall protection system takes into account:

AOA
Lateral acceleration
Flap position
weight on wheels
mach

[Windchill]

Originally Posted by kfour

Who comes in to land with full power anyway?

Aircraft Carrier Pilots? But they also face the probability of going over the deck into the ocean.