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744lover
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A340 Takeoff Performance Calculations

Tue Sep 11, 2018 6:12 pm

Hi,

While watching this video (poor A340 being bashed again), I couldn't help but notice far down the runway the airplane rotated. Look at 1:13 and you'll see that it went airborne over the piano keys!

https://www.youtube.com/watch?v=_qXhD-RhRo4

Here is the airport ADC chart (http://ais.decea.gov.br/download/?arquivo=ba2a7fb0-da94-43d3-abeb5d5b8d2783eb&apikey=1587263166) . From the video it seems he went airborne where the chart says "ELEV 2170'"

Wrong takeoff numbers calculations? Insufficient rotation rate?


Thanks,
744lover
 
FriscoHeavy
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Re: A340 Takeoff Performance Calculations

Tue Sep 11, 2018 7:24 pm

Wow. Normally, it's an optical illusion, but that certainly used about every foot of runway. This isn't to knock the A340 -- it's a great aircraft, but there is no way that plane would have gotten off the ground by the end of the runway had it lost an engine at/after V1.
Whatever
 
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trpmb6
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Re: A340 Takeoff Performance Calculations

Tue Sep 11, 2018 8:23 pm

Hard to say.. Nose does look like it was off the ground for a fair bit of time. more than I originally thought, so rotation did seem a bit slow. It was a charter, do we know what they were carrying Pax and cargo wise? May have needed every bit of runway depending on weight and current conditions. Looked hot out.
 
LH707330
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Re: A340 Takeoff Performance Calculations

Tue Sep 11, 2018 11:52 pm

It's off at the 1:12 mark, which looks to be 1500 feet down the runway. At 1:13, you can see the thousand-footers disappear underneath the aircraft. That said, they were not 35 feet by the end of the runway....
 
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Starlionblue
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 12:17 am

Purely for fun, because it is very hard to tell anything from the outside, I guesstimate the rotation time at 7 seconds. On the high end, but still acceptable.

Once established, meaning the first few degrees are slow, rotation rate should be 2-3 degrees per second up to the initial target pitch of 12.5 degrees. Rotation rates below 2 will start having a significant impact on the take-off run.

Again, though, very hard to tell anything from the outside.
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glen
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 11:05 am

For me it seems the main problem with this take-off is not only the rotation rate but mainly the too low pitch attitude at the end of the rotation. As mentioned by Starlionblue the target pitch is at 12.5°. Considering the fact that tailstrike with compressed main gear is at 10° and looking at the video it doesn't seem to me, the aircraft ever reaches the target pitch. Of course it can be an optical illusion, but it looks like the aircraft does not even exceed 10° at any stage.
At least 7-8° pitch are required for a heavy A340 to lift-off. Staying only slightly above this value and not continuing the rotation to its target pitch increases the take-off distance considerably.
"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein
 
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Starlionblue
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 11:13 am

Well spotted glen. It appears as if the rotation is not continued once the wheels leave the ground, or at least only continues very slowly and too late.

Again, though, we'd need to see the instruments. :)
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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trpmb6
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 1:16 pm

Yeah, all of this is complicated by the movement of the camera, not a stationary position and lets be honest, who here can tell the difference between one and two degrees??
 
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zeke
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 2:14 pm

The zoom lense makes this look different to what it is, the nose wheel was rotated by the time it got to exit F (the tower in the background at 1:04) and the mains were off the ground by about 1400 ft to the end of the clear way looking at the building adjacent to the runway.

Taken from location 2 http://www.spotterguide.net/planespotti ... -vcp-sbkp/
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GalaxyFlyer
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 5:24 pm

glen wrote:
For me it seems the main problem with this take-off is not only the rotation rate but mainly the too low pitch attitude at the end of the rotation. As mentioned by Starlionblue the target pitch is at 12.5°. Considering the fact that tailstrike with compressed main gear is at 10° and looking at the video it doesn't seem to me, the aircraft ever reaches the target pitch. Of course it can be an optical illusion, but it looks like the aircraft does not even exceed 10° at any stage.
At least 7-8° pitch are required for a heavy A340 to lift-off. Staying only slightly above this value and not continuing the rotation to its target pitch increases the take-off distance considerably.


I’ve flown with guys that learned on Aztecs and Barons where getting to “blue line”speed quickly was everything to survival in the case of engine loss. They never got over that even in jets—slow rotations, V2+30 at 50’, etc, rotate to 8-10 degrees when the target in type was 15-17*.

GF
 
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glen
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 9:50 pm

GalaxyFlyer wrote:
I’ve flown with guys that learned on Aztecs and Barons where getting to “blue line”speed quickly was everything to survival in the case of engine loss. They never got over that even in jets—slow rotations, V2+30 at 50’, etc, rotate to 8-10 degrees when the target in type was 15-17*.

GF


That, and some are over-careful, because they are afraid of producing a tailstrike.
"The horizon of many people is a circle with zero radius which they call their point of view." - Albert Einstein
 
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zeke
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Re: A340 Takeoff Performance Calculations

Wed Sep 12, 2018 10:13 pm

GalaxyFlyer wrote:

I’ve flown with guys that learned on Aztecs and Barons where getting to “blue line”speed quickly was everything to survival in the case of engine loss. They never got over that even in jets—slow rotations, V2+30 at 50’, etc, rotate to 8-10 degrees when the target in type was 15-17*.

GF


The video is deceptive as the observation point is about 350 m past the threshold 850 meters away from the centerline, that makes it a angle of 20-30 degrees to the takeoff path. This give the illusion that the flight path is about 30% shallower than it actually is.
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T54A
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Re: A340 Takeoff Performance Calculations

Mon Sep 17, 2018 2:39 pm

The video can be deceiving. You can’t tell what Flex thrust was used. A max Flex thrust take off will use more runway than a TOGA take off assuming there is a large margin at play.
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lightsaber
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Re: A340 Takeoff Performance Calculations

Mon Sep 17, 2018 3:52 pm

It is well known the A340 doesn't take off, it uses the curvature of the earth to have the ground fall away. :duck:

Seriously, it is camera perspective. :yawn:
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wing
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Re: A340 Takeoff Performance Calculations

Wed Sep 19, 2018 7:14 pm

When I first started flying the A340-300 ,it had a very different feeling during rotation compared to A330 It made me feel that the nose is heavier than normal and creates an instinct to pull the side stick harder to achieve the rotation, which instantly triggers the fear of a tail strike than your reflex is to ease the rotation rate, thus ending up with a sluggish nose rotation.If you look closely after lift off(about the time it passes over the highway) the pilot feels that the tailstrike is no longer factor,increases the pitch with the rate actually it is supposed to be.
Improper rotation has many different reasons like all the other mistakes we do while flying,experience on the type is the key to solve most problems,proper training is a must.
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MassAppeal
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Re: A340 Takeoff Performance Calculations

Thu Sep 20, 2018 1:58 am

Amazing how we never have "deceptive camera angles" of modern Boeing widebodies barely becoming airborne... ;)
 
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zeke
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Re: A340 Takeoff Performance Calculations

Thu Sep 20, 2018 5:31 am

Prehaps you are not looking
Human rights lawyers are "ambulance chasers of the very worst kind.'" - Sky News
 
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exFWAOONW
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Re: A340 Takeoff Performance Calculations

Fri Sep 21, 2018 7:55 pm

Was it a charter for footballers? As we all know, they don't fit the standard pax/bag weights very well. If somebody use the wrong chart, The A/C could have been configured at less than optimum. I know this is a possibility as I *almost* did this when I had to do a manual W/B once. Fortunately, I caught it in time to do it right. Since it was a DC9-30, it really didn't make much difference on the stab setting, but not every a/c is so forgiving.
Is just me, or is flying not as much fun anymore?

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