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-   -   Do we “bump down” these days? I was taught to land…… (https://www.pprune.org/pacific-general-aviation-questions/119143-do-we-bump-down-these-days-i-taught-land.html)

Cloud Cutter 17th Feb 2004 06:48

Depends on your definition of decent landing. For me, it is getting as close as possible to what the aircraft flight manual says you should do.

dogcharlietree 17th Feb 2004 07:03

1) Pax ALWAYS judge a pilot by his/her landings only.
Nothing else matters to them.
2) Friends of mine who constantly fly domestic in Oz are always commenting on the HARD landings these days. What has changed, they ask me. Ah.. I reply, the standard of the aviator!!!!
3) Aircraft with trailing link undercarriage (ie the one-four-sex whusper jet) by design allow for smoother landings.
4) The different aquaplanning speeds should be considered for landings and aborted takeoffs.
5) Some aircraft have spoiler deployment after main wheel spinup. ie Diesel 9.
6) Conditions in Oz (weather and runways) are almost always in our favour to conduct smooth landings (for RPT).
7) From my old friend AC Kermode (Mechanics of Flight) "The art of landing an aeroplane consists of bringing it in contact with the ground at the lowest possible vertical velocity and, at the same time, somewhere near the lowest possible horizontal velocity relative to the ground."
8) Ah, I'd like to see some of these so called pilots these days land a DC-3. I'd make a motza selling seats, for spectators, coz nobody would ride with them.

404 Titan 17th Feb 2004 09:01

Some of you seem to be making the stupid mistake of rating the landing quality to determine the pilot’s skill. You should realize though that a large number of airlines, mine included, emphasize toughing down in the “Zone”, rather than a smooth landing. If you can achieve both then great, but certainly don’t go out of your way looking for it. As the pilot gets more experience on type he/she will be able to achieve it more often but ultimately conditions on the day will dictate the outcome to every landing, not just the skills of the pilot.

Kaptin M 17th Feb 2004 14:20

IMO, you're quite correct, 404 Titan, after all isn't that part of what being a professional pilot is about.
The history pages are filled with pilots who tried to "grease it on" and eventually probably did. but ended up running out of runway and damaging the aeroplane.
As a matter of fact, I was just reading about an incident in the States where the Captain overran the runway, because he persisted in trying to land when he should have gone around ie. he touched down with insufficient runway length remaining. Not only did he not realise the aircraft limitations, but neither did the F/O (who should have told him to go-around).
The final words on the CVR transcript by the (52 y.o) Captain were, "Well, there goes my career".

I wonder if Bob Katter and Wayne Swan might have written him a letter of thanks for NOT going around, had they been on board at the time :rolleyes:

NAMPS 17th Feb 2004 14:59

I saw the nicest landing in marginal wx at Coffs once.

It was a greaser...just happened to be on the old rwy 19 (turned taxiway). Pulled it up nicely too!

;)

Dogimed 17th Feb 2004 18:30

Namps,

By these other philosophies, he/she must have been a very unprofessional pilot.

Kaptin M,

I'm not saying to risk life/career/plane.. just wanted to know if pilots were being taught that a good landing seems to show that the pilots aren't just sighing at the end of a flight and after all. IT IS what pax remember ...

404 Titan


Some of you seem to be making the stupid mistake of rating the landing quality to determine the pilot’s skill. You should realize though that a large number of airlines, mine included, emphasize toughing down in the “Zone”, rather than a smooth landing
You just answered my original question.

DCT
Someone told me recently

" A good landing is one you can walk away from, a great landing is when the aircraft can be reused."

Perhaps that is in the Ops manual?

Dog

Wingnuts 18th Feb 2004 09:30

"Aquaplane speed is a function of tyre pressure and speed and weight has no effect ..... "

True, but pressure is dependent on tyre air volume which is dependent on tyre profile which is dependent on weight.

That is, the firmer the landing, the greater will be tyre distortion from max volume, 'round' profile. Hence the pressure will increase and aquaplane speed will be higher.

As the wheel spins up, centrifugal force will tend to restore the round profile and lower the aquaplane speed. How much depends on oleo pressure which depends on weight which depends on.......

--------------------

The bloke who ops for a greaser rather than a positive touch down on 'the spot', is generally the same bloke who does not have an issue with not using full runway length for takeoff.

Dogimed 18th Feb 2004 10:04


The bloke who ops for a greaser rather than a positive touch down on 'the spot', is generally the same bloke who does not have an issue with not using full runway length for takeoff.
Why can't you greaser on 'the spot'????

Dog

dogcharlietree 18th Feb 2004 15:03

C'mon Guys, We're not talking about the once-in-a-blue-moon 'greaser'. (which is probably around or less than 1in/sec).
I don't think the PAYING pax or us expect this unrealistic greaser.
All we want is an acceptable and bearable rate of descent when the flying machine contacts terra firma.
We are trying to workout why pilots these days test the vertical limit imposed by FAR's of 10ft/sec continuously.
There was an article that appeared in the flying magazines a few years ago which talked about the "Jacobson Flare", written by David Jacobson, a QF 737 training captain. Unfortunately I cannot find it on the 'net.

Soulman 18th Feb 2004 19:12

Thank God I'm Young!
 
Well, I can't say I fly a Triple 7 or a 73' (actually I fly VH-HXK - A Piper Warrior at Horsham) and while I might only have 8.6 hours flight time - I'm pleased to say that I'm learning how to land (at least better than my first few attempts!). Cut the power over the fence, glide, hold off, hold off, hold off, back pressure, back pressure, back pressure... Ahh, Got it down! And what's more, I'm on the centreline and have plenty of black stuff in front of me (and only a little behind me!)

Interesting thread - I love reading about how you guys in the majors do your thing - hopefully one day I can join in threads like this with the knowledge of an Airline Pilot. ;)

Cheers and wish me luck.

Soulman.

amos2 18th Feb 2004 19:23

You stick with it Soulman and you will make the grade...after all, that's how we all started.

Now, back to the so called experts!...

Gimmee a break fella's, if you've been around the traps a few years, especially in airline ops, and you can't put it on smoothly more times than not,then God help us all!!

I could do it, why can't you?

Chimbu chuckles 18th Feb 2004 22:29

Soulman that's great in a Piper but try it in a jet and you'll;

1/. Smash the tail on the ground, or

2/. Drop 140 tons of aircraft in from several feet up...making the 'bumping down' landings discussed here look like greasers!!

The main undercarriage in a jet is almost always (edit: a long way) behind the axis around which the aircraft pitches...hence if you keep pulling back 'for a greaser' the opposite will result, you'll drive the wheels into the runway...presuming you don't bash the tail on the ground doing millions of $ of damage first.

You can get nice landings that impress the punters but that is not the imperative. You must land in the defined touchdown zone OR ELSE!!!

When you land a jet you, most often, fly an ILS and then when the talking radalt says 50' gently pitch up a few degrees, to arrest the rate of descent, and when you hear 20' gently reduce thrust and just let it land...timed right you get an 'acceptable' landing...it's all in the timing. To get a more consistant 'really nice' landing you can gently reduce back pressure (after the pitch up) to 'lift' the rear wheels enough to further cushion the touchdown...often, if done right, earning yourself a greaser...but not always.

In some conditions the most professional thing to do is just 'put it down' in the right place!!!

Now to the matter of 'wet runway' techniques.

The most abused/missunderstood technique is this thing about slamming an aircraft on the ground on 'wet' runways....it's a STANDING WATER technique NOT A WET RUNWAY ONE!!!!!

The number of dickheads, including senior captain/check captain dickheads, I've seen prolapse every heamoroid on the aircraft because a runway is 'wet' is truly amazing.

It's for landing on up to 1/2 inch of standing water...not bitumen discoloured by rain...even steady rain. Given most big runways are grooved is even less reason to ever have to drive an aircraft on using a technique designed to drive the wheels down through deep water to get to the actual runway!!!

Hands up any airline pilots who have an ops manual that allowes operations in standing water/innundated runways??

Chuck

flyboy6876 19th Feb 2004 06:12

You mean sort of like this Dogimed?

Not a Piper, but a jet

DirectAnywhere 19th Feb 2004 06:49


The main undercarriage in a jet is almost always behind the axis around which the aircraft pitches
Chimbu, I would hope so! Given that an aircraft pitches about its lateral axis which runs through the CoG, if the CoG was aft of the main wheels the aircraft would sit on its tail on the ground. I think the main wheels on ANY aircraft that's correctly loaded are aft of the CoG. The longer moment arm between the CoG and the main wheels on a jet leads to the problem you've described, not the fact the CoG is ahead of the wheels.

Wingnuts 19th Feb 2004 07:47

Dog

To grease it on, your sink rate has to be minimum. Or you can 'roll' it on a la 727 so that the mains are going up as the aircraft hits the deck. You risk a very firm landing if you are too late and float if you are too early. Only recommended for the aces.

Another way to arrest sink is with a spurt of power, again not recommended as it increases fwd momentum, speed, fuel, brakes and distance. Or duck below approach angle and level out prior to touch down on 'the spot'. Risk is landing short (unexpected sheer, power loss) and approach obstacle clearance but in both cases, the pax will be impressed.

But it depends on the aircraft, wingloading etc. The 747 will grease it on almost every time because of cushing ground effect as will the 146 because of very forgiving gear geometry.

Dogimed 20th Feb 2004 04:24

Why is this is Questions?!?
 
Woomera? Moving it here has killed the thread.

Dog
:{
Ho hum...

Bevan666 20th Feb 2004 08:14

I think what Chimbu Chuckles is trying to say is on a bigger aircraft, with the main wheels behind the CoG a small change in attitude will produce a significant movement in the position of the main wheels.

In smaller aircraft, a 1 degree pitch change might move the wheels up and down by an inch or so, while on a larger aircraft this will be a number of feet.

This is all due to the distance from the CoG to the main wheels.


Bevan..

DirectAnywhere 20th Feb 2004 19:40

Agreed. But the point I'm making is that Chimbu stated the main wheels are ALMOST always aft of the CoG in a JET.

The main wheels are ALWAYS aft of the CoG in any aircraft. As I stated (maybe re-read my original post?), the moment arm, ie. the distance between the wheels and the CoG is what makes the difference, not the fact that the main wheels are "almost always" behind the CoG.

hoss 20th Feb 2004 19:59

"the main wheels are ALWAYS aft of the CoG in any aircraft"

Try telling that to the DC-3 guys out at Bankstown:ouch: :ok: .

:)

DirectAnywhere 21st Feb 2004 04:30

Ooopsss...in any tricycle undercarriage aircraft. Ta!!!:\


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