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Departing Saudia Cargo 747 'departs' runway

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Departing Saudia Cargo 747 'departs' runway

Old 12th Nov 2017, 18:46
  #21 (permalink)  
 
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I flew both 744 and 330 and stand by my comment..
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Old 12th Nov 2017, 19:26
  #22 (permalink)  
 
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I see all four thrust reversers deployed on the photograph above.
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Old 12th Nov 2017, 20:41
  #23 (permalink)  
 
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Maybe an A380 could be more difficult as the outer engines are further away from the CoG?
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Old 12th Nov 2017, 21:21
  #24 (permalink)  
 
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Sorry, could well be true, probably similarly (or more) challenging, have no idea and wasn't out for a contest.
Was a bit annoyed by the armchair pilots criticizing a crew without having any idea and thinking that just cutting the power is enough to keep it on the runway
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Old 12th Nov 2017, 22:11
  #25 (permalink)  
 
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Originally Posted by fox niner View Post
I see all four thrust reversers deployed on the photograph above.
That could be a possible complexifier...

Thrust levers back and up to the reverse idle detent is one way to ensure the autothrottles are disengaged during a low-speed reject. HOWEVER, if all 4 throttles are brought to full reverse, they can take you off the runway almost as quickly! Been there, done that in the sim...

Our training center has enforced several different routines over the past 20 years. Currently, they want to see thumb squarely on the autothrottle disconnect lever until the "80 knots, thrust set" call. Personally, that takes my other fingers higher up on the thrust levers, with an increased probability of my pinkie slipping off #4. That could be a REAL problem when #1 fails...
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Old 12th Nov 2017, 22:45
  #26 (permalink)  
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Everybody thanks for your interesting contributions.

Based on two images on the AvHerald page Incident: MyCargo B744 at Maastricht on Nov 11th 2017, runway excursion on takeoff for this incident, one by Jan Severijns with a shallow peaked-roof hanger in the background and beyond it a very conspicuous antenna tower, and the image by Jeroen Stroes on that same page with the very dark brown ‘Koninklijke Marechaussee - Brigade Limburg Zuid’ office building visible under the side view of the tailplane (with the elevator hinge line pointing to the office complex), as well as an earlier nighttime photo in which the GS antenna for runway 21 is visible in the foreground https://pbs.twimg.com/media/DOY2K42W4AAJU03.jpg, my (plumb bob) finding on Google Earth is that the a/c heading is almost exactly 45 degrees veered to the right of the runway heading. And it looks as if the tail and the LH wingtip are still just over or just clear of the runway shoulder.

My resulting plot differs considerably (closer to the beginning of the runway) from Simon’s on AvHerald, but he came first, with a position, so he left the heading for me).

Been flying and seen flying close to runway edges more than once :-)
Attached Images
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Old 12th Nov 2017, 22:48
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I've flown both the 747 and the 380, and the low speed failure of an outboard engine will have you on the grass in seconds. Not an easy failure by any means.
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Old 12th Nov 2017, 23:15
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Okay, so I correct my comment about twins like A300.
The largest 4holer I have flown was A340 but as we all know it has only 4 hair dryers
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Old 12th Nov 2017, 23:41
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At least it looks repairable unlike their tarmac excursion with a 747 many years ago, see below

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Old 13th Nov 2017, 03:55
  #30 (permalink)  

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Originally Posted by mrdeux View Post
I've flown both the 747 and the 380, and the low speed failure of an outboard engine will have you on the grass in seconds. Not an easy failure by any means.
Yeah, one has to be on one’s toes to say the least.
Back in my 747-200 Days we practiced numerous low speed engine failures as part of the 3 engine ferry simulator training. With 2 out on the same side things got interesting really fast when slow.
To Hell in a hand basket as the Yanks would say..
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Old 13th Nov 2017, 07:51
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That Saudia 743 with its nose in the drain was not during take-off or landing. It was being taxied out of a engine run pen and IIRC they did not have hydraulics fully on line, hence no steering or brakes.
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Old 13th Nov 2017, 11:28
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The aircraft (from the MST incident) was recovered last night. Airport back to normal ops since 11:00 UTC today.

Last edited by Hotel Tango; 13th Nov 2017 at 15:18.
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Old 13th Nov 2017, 14:25
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Nothing to add, except what an FE told me as a new hire FO on the 747, 13 years ago: The nose wheel is basically there for decoration. All the weight is borne by the main gear, so they act like a pivot during low speed engine failure.
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Old 13th Nov 2017, 16:33
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When I did my 747 classic course in a previous century I was taught that the typical weight on the 747 nosewheels was between 5 and 12 tonnes. When the 747-400 came out they had considered moving it to have a bit more weight on it but that would have made it a new aircraft design and certification would have taken for ever.

So here's a question for you. if the designers wanted more weight on the nosewheel would they move it backwards or forwards? A lot of people think the answer is forwards....
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Old 13th Nov 2017, 17:52
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Consider a simple [1] child's seesaw.
The balance point is the main gear axle, the nosewheel is balanced by the weight of the tail. Moving the nosewheel forward will give it more leverage and therefore lighter.

[1] The seesaw not the child.
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Old 13th Nov 2017, 18:05
  #36 (permalink)  
 
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That Saudia 743 with its nose in the drain was not during take-off or landing. It was being taxied out of a engine run pen and IIRC they did not have hydraulics fully on line, hence no steering or brakes.

Yep, maintenance guy taxied it out of the gate with unqualified helper in FE seat.
Declined help of tech crew sitting in the upper deck.
Taxied at warp speed - without Hyd for brakes/steering.
Sad end to a great aircraft just out of overhaul AIO
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Old 13th Nov 2017, 22:30
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Now if you did move the nose-leg rearward you would indeed get a greater vertical load going through it, but at the same time you are increasing the sideways load from the assymetric engine thrust and so it would be more likely to skid sideways allowing the aircraft to yaw!
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Old 13th Nov 2017, 22:56
  #38 (permalink)  
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Originally Posted by suninmyeyes View Post
So here's a question for you. if the designers wanted more weight on the nosewheel would they move it backwards or forwards? A lot of people think the answer is forwards....
Neither - either move the main undercarriage or redistribute the weight / CofG so that more weight is loaded onto the nosewheel.
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Old 13th Nov 2017, 23:50
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Lots of current cars have stability control systems that automatically apply differential braking to prevent excessive "yaw." It doesn't seem like it would be technically difficult to install a version of that on an aircraft, perhaps set to be active only if there's an uncommanded thrust reduction on an outboard engine below 80 knots (or something like that). But I guess it's late in the 747 lifecycle.
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Old 14th Nov 2017, 00:40
  #40 (permalink)  

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I had the nosewheel on the 747-100/200 slide sideways across dry pavement many times, a lot less than 5-12 tons weight on it. Try 500 kilos if empty.
(Yes, we used center tank ballast fuel when flying empty but the nose still seemed very light, steering was best done with brakes and power.)
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