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747 "wheelie" landing???

Started by Zapp, Fri, 29 Aug 2014 21:11

John H Watson

Actually, the nose in the air method is the more traditional way. The early US 747 flyers seemed to do this. I recall that Lufthansa did a study on landing techniques (or were one of the first to implement the results of the study) which proved the nose down early method was the most efficient. From what I saw at my local airport, the American carriers  were slow to change.

Who trains the El Al pilots these days?

Phil Bunch

Wheelie landing is usually just aerodynamic braking of a sort, isn't it?  This is not to say that this type of aero braking is a good idea with modern brakes, etc.

I seem to recall that the Concorde had to land this way due to its normal low drag.
Best wishes,

Phil Bunch

Will

#22
Very interesting, JHW. I've only seen the 3-4 second method, not the 12 second method. Perhaps I just wasn't looking. Certainly I can say that my airline (and I was an instructor!) taught pilots to put the nose down promptly, consistent with safety and comfort. You didn't want to slam the nose down but you did want to get it down soon, so you'd get maximal brake effectiveness and improved directional control. 3-4 seconds was about right.

I noticed that with PSX on LAND 3, the autopilot lowers the nose in about 3.5 to 4.5 seconds. I wonder if the autopilots back in the earlier days also took 12 seconds to get the nose wheel on the ground?

Hi Phil, as I think we may have said earlier on the thread, aerodynamic braking was useful for airplanes that didn't want to carry the extra weight of heavy and robust brakes. I can't speak to Concorde, but many old fighter jets, including delta wing jets that were similar to Concorde, would forsake the weight of beefy brakes and instead rely on aerobraking (or a parachute) to slow down after landing.
Will /Chicago /USA

Jeroen Hoppenbrouwers

#23
A side effect of WANTING to keep the nose up may be that you are more careful to touch down lightly, to avoid dropping the nose on impact. The result of this may be what we see here, that the El Al floats a lot longer than the Delta. El Al is over the runway lower, but touches down further.

This difference is small, though. You can only see it with the two videos next to each other and stopped on runway markings. It may simply be visual aiming.


Hoppie

Will

This conversation is making we want to take a day off of work and go to O'Hare for plane spotting.
Will /Chicago /USA

John H Watson

Quote from: WillVery interesting, JHW. I've only seen the 3-4 second method

I'm sure the nose down early method is the more common now, Will.
 By "traditional", I meant the original nose up method, going back to Pan Am days  :mrgreen:

Will

My first trip overseas was on a Pan Am 747... All I remember was thinking that the interior looked to be as big as an office building. I was amazed that it kept going back for row... after row... after row... I was about 12, a perfect age to be amazed. I can't remember anything about the landing. :-)
Will /Chicago /USA

Avi

Quote from: WillThe El Al crew definitely does something different. I'd love to know what the reason was. Were they taught to hold the nose off as long as possible? (If so, why?) Was this taught as an alternative to the "traditional" way? (If so, under what circumstances is this style recommended?) Was there possibly some other reason for doing what they did?
I don't know what happened here. Maybe it is a young pilot. As I said, this is the first time I see aircraft does it (*) and I don't think it is a policy in El Al.

Quote from: JHWWho trains the El Al pilots these days?
I have no idea.

Cheers,

* Now that I think about it, it could be the second time I see it but I can't be sure.
From my house balcony I can see a very short portion of RW21 with a binoculars (actually the area just above it but I can see aircraft) and I remember an El Al 747 after landing with its nose still up.
I thought at first it did a late touchdown (because in all the other times I saw B747s they were firmly on the ground) but now I think it kept its nose in the air as this one in the video. Anyway, I could see them only for about 2 sec so it is too short to tell/know.
Maybe there is one pilot who does things his way.
Avi Adin
LLBG

Phil Bunch

#28
I thought all or most El Al pilots are ex-military, probably ex-fighter pilots - if so, maybe that would explain their use of aero braking?
Best wishes,

Phil Bunch

Hardy Heinlin

Where are the spoilers on the Delta?

And ... does the Delta have an extra large ADF antenna?

John H Watson

Quote from: Hardy HeinlinWhere are the spoilers on the Delta?

Maybe that's why the nose went down so quickly? He was expecting the nose to pitch up with spoiler deployment and pushed forwards, but the spoilers didn't come up.

QuoteAnd ... does the Delta have an extra large ADF antenna?

Or a repositioned normal sized Satcom antenna?

IefCooreman

#31
It's all rough guesswork, but some thoughts...

The way you are being trained today is to hold off the nose slightly to prevent hard impacts of the nose wheel on the ground. There have been many many cases of damage (from the minor nose strut leak to completely cracked fuselages) due to hard de-rotations. It needs to be done as smoothly as possible. But avoid the discussion with  MD-11 drivers, they crash trying to save the nosegear :-(.

When the main gear touches down firmly the nose needs to be "supported" because the brakes will activate automatically. Pushing the nose down at that point is dangerous. Once the brakes activate, off course the nose needs to come down to allow full reverse. And yes, there is always the group of pilots that exagerate, and hold it off very very long. As long as you don't apply more than idle reverse (which is prefered anyway) it is not really dangerous. But it is true at some point the elevator will run out of authority and ... you get the same result (nose wheel slamming on the ground).

The different nose gear movement in the video is (in my opinion) related to touchdown speed.

From what I see, the Transaero and El Al have a touchdown speed that is on, maybe slightly above target (logical for the Transaero because of the crosswind). In those cases it is very easy to support the nose wheel, it just stays in the air by itself. Since you are ready to "support" you are waiting for the speed to bleed of normally before the nose starts coming down. It might need a little push, but you need to be very carefull.

The United seems to be slightly below target speed on touchdown. The nose "bounces" down quickly. and all you can do is pull hard on the yoke to stop that downward movement. You can see the de-rotation happens in two steps (you can even see it on the elevator): touchdown with nose continueing to go down, then it stops which is the pilot intervening by pulling hard on the yoke, releasing it again, and the nose continues to drop quickly.

Your touchdown speed determines whether you can actually "fly it on the runway", or "drop it on the runway".

The United reaction was actually pretty similar to my first encouter with runway 30 in LLBG. Interesting approach and a 45m wide runway which actually is a lot wider (big shoulders) and hence gives the impression of "fat and short". It makes you fly on target and prefer slightly firmer touchdown on the right spot :-). When you've stopped you realise there's still plenty of concrete in front of you...

Avi

Quote from: PhilI thought all or most El Al pilots are ex-military, probably ex-fighter pilots
In the past it was all (100%), today it is most (~97%) but the air force pilots come from "all over the place".

Quote from: IefCooremanWhen you've stopped you realise there's still plenty of concrete in front of you...
I knew once a pilot who said that a pilot doesn't want to regret 3 things:
• The runway behind him.
• The altitude above him.
• The fuel in the tanker.

The Delta spoilers are a mystery. Even if they didn't arm them for landing (something I found hard to believe because I don't think they didn't do their before landing checklist), they should have deployed when the pilots applied reverse thrust (unless they had an electrical problem and the auto speedbrake actuator wasn't powered).

Cheers,
Avi Adin
LLBG

Will

#33
I emailed this question to a friend of mine who is currently a 777 captain, but flew F/O on the 747-400 for over 10 years, starting in about 1995. He said the following:

•  Pilots know about aerobraking but it was never taught to him or mentioned as a technique for the 747, so if people did "wheelie landings," it was not for the purpose of aerobraking;

•  S.O.P. at his airline has always been to get weight-on-wheels (WOW) as soon as possible, especially on short runways, wet runways, or unfamiliar airports;

•  He thinks the wheelie was done to increase the perceived smoothness of the landing and he guessed that El Al would have gone WOW more promptly had they been going into an unfamiliar airport at night;

•  He was taught that it's safer to get used to one technique and do it all the time on every landing, instead of doing wheelies sometimes and WOW other times, since in times of uncertainty, people tend to fall back on what they are most familiar with;

•  But that being said...  wheelie landings extend the rollout, and sometimes crews will deliberately extend the roll if they're going to park at a gate that's at the opposite end of the airport, and, since the wheelie feels smoother to the pax and cabin crew, it might be an acceptable thing to do at a familiar airport on a sunny day, when the gate is far away.

Those were his thoughts.
Will /Chicago /USA

Avi

Here is another piece of information about the Delta 744 (regarding the spoilers).
This aircraft is N669US. Today it returns to TLV. It is going to takeoff late (by 3 hours at least) because of a malfunction (I wish I knew what is the problem but I can't ask my mom to ask the crew :mrgreen:).
They were already on the aircraft, after 1.5 hours they left it and now it seems (in flightradar24) things start moving.

It looks like a problematic aircraft.

Cheers,
Avi Adin
LLBG

Hardy Heinlin

Is your mom on that aircraft? I'd love to see the face of the captain when your mom would ask him, "Is the spoiler problem fixed now?"


|-|

Avi

Yes she was.

I tried to get to the airport in time to check it out but missed by a minute or two (but from the bridge in front of the terminal I probably wouldn't see them without the camera or binoculars which I didn't have.

She said someone said there was an issue with one of the cargo doors but...

Cheers,
Avi Adin
LLBG

IefCooreman

I believe the spoilers deployed but impossible to see, and the captain retracted them pretty soon together with the reverse. Not very by the book, but happens sometimes with captains who once forgot about them completely :-)

Avi

Actually, this is exactly what the El Al crew does. If you take a look again you will see the spoilers going down right after the reversers restored.

I watched the videos again simultaneously and checked when the El Al spoilers became visible.
They were visible about the time the Delta nose gear touchdown. Giving the fact that the El Al kept the nose in the air (wing hiding the spoilers), the Delta spoilers had to be seen and they were not.

Cheers,
Avi Adin
LLBG