Cargo Crash at Bagram
Unbelievable...... It seems like just yesterday that this forum was filled with professionals that knew their trade and posted relevant information. I guess it was a few years ago now.
There must be three amateurs for every pro now. Getting hard to wade through the rubbish to find the gems
There must be three amateurs for every pro now. Getting hard to wade through the rubbish to find the gems
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"Would it be possible - the next time there is a tragic accident / incident that there are two crash threads - one for pilots / engineers and the qualified to post on - the other clearly labelled for irrelevant drivel?"
Just add the irrelevant drivel spewing individuals to your ignore list in your "user CP" section.
You're right though, the thread has become largely irrelevant. There has not been any useful/factual information posted in here for days.
Just add the irrelevant drivel spewing individuals to your ignore list in your "user CP" section.
You're right though, the thread has become largely irrelevant. There has not been any useful/factual information posted in here for days.
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..."but I strongly believe that in the end it will be shown that if cargo shift played a role in this event, the shift occurred during takeoff roll on the runway and not after leaving the ground."
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NumeroUno wrote:-
"There has not been any useful/factual information posted in here for days. "
that's the case in just about any accident reported on here - there is about 5 minutes when people think of the poor sodds who lost their lives, about another 10 whilst the basic facts are determined and then a hurricane of guesswork descends, often skewed by whatever agenda people already have (Airbus v. Boeing, heritage carriers v. LCA's, first world v. third world...)
Eventually about two years later we find out what really happened
"There has not been any useful/factual information posted in here for days. "
that's the case in just about any accident reported on here - there is about 5 minutes when people think of the poor sodds who lost their lives, about another 10 whilst the basic facts are determined and then a hurricane of guesswork descends, often skewed by whatever agenda people already have (Airbus v. Boeing, heritage carriers v. LCA's, first world v. third world...)
Eventually about two years later we find out what really happened
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Energy transfer - Kinetic to Potential
etang,
You posed the question: "If the cargo shifted during takeoff roll, or on rotation, how did the plane manage to reach the altitude seen in the video?"
What appears to have happended (cargo shift or not) is that the airplane rotated to a very nose high attitude and climbed sharply. What took place was a transfer of the kinetic energy the airplane had built up during the takeoff roll into potential energy of altitude gain. Going back to basic physics here are the equations for Kinetic Energy as a function of velocity (feet per second) and Potential Energy as a function of altitude (feet).
Kinetic Energy = 1/2 mass * velocity^2
Potential Energy = mass * gravity * altitude
With these units gravity is 32.2 feet per second squared.
Using these two equations and solving for the altitude increase that would result from converting all kinetic energy to potentail energy yields:
Altitude change = Velocity^2 / (2 * gravity)
If the velocity at rotation was 150 knots the equation above yields an altitude change of 1000 feet. If the velocity at rotation was 175 knots the resultant altitude change works out to be about 1400 feet.
It is not at all surprising that a 747 would climb to about 1200 feet if following takeoff rotation the crew was not able to keep the nose from pitching up to a very steep angle leading to stall. Keep in mind that the engines were continuing to add energy during at least a portion of the climb.
You posed the question: "If the cargo shifted during takeoff roll, or on rotation, how did the plane manage to reach the altitude seen in the video?"
What appears to have happended (cargo shift or not) is that the airplane rotated to a very nose high attitude and climbed sharply. What took place was a transfer of the kinetic energy the airplane had built up during the takeoff roll into potential energy of altitude gain. Going back to basic physics here are the equations for Kinetic Energy as a function of velocity (feet per second) and Potential Energy as a function of altitude (feet).
Kinetic Energy = 1/2 mass * velocity^2
Potential Energy = mass * gravity * altitude
With these units gravity is 32.2 feet per second squared.
Using these two equations and solving for the altitude increase that would result from converting all kinetic energy to potentail energy yields:
Altitude change = Velocity^2 / (2 * gravity)
If the velocity at rotation was 150 knots the equation above yields an altitude change of 1000 feet. If the velocity at rotation was 175 knots the resultant altitude change works out to be about 1400 feet.
It is not at all surprising that a 747 would climb to about 1200 feet if following takeoff rotation the crew was not able to keep the nose from pitching up to a very steep angle leading to stall. Keep in mind that the engines were continuing to add energy during at least a portion of the climb.
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I hate repeating myself, but you 'experts' implying that an acceleration due to engine thrust can have the same net effect on the cargo as gavity does when the aircraft is climbing and thus concluding the situations are the same, are completely ignoring the fact that the component of gravity that was pulling the load onto the deck is now greatly reduced................this is not a small factor kiddies
Basic stuff, FFS
Basic stuff, FFS
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Having read just about every post on this thread, I can understand the frustrations felt about those who think they know, by those who actually do. However: restricting participation/visibility to the latter - as seems to have been suggested - could close out an unknown number of infinitely less qualified people such as myself, who have in fact learnt a lot from this debate while also having the sense to keep the lip zipped. I say this as an amateur GA pilot & gliding instructor, and newcomer to the PPPrune scene, who has over many years had the misfortune to be an eyewitness to the deaths and serious injuries of several friends in stall/spin accidents, and it would sadden me to be denied the opportunity to learn from the wealth of knowledge and experience embedded in this thread, if only as a silent onlooker. (And yes, I fully appreciate the quantum differences between 744's and K13's/Super Cubs, but the fundamentals of physics and aerodynamics are still applicable).
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jetblu, the memorial page is an honorable tribute however I find the request for donations questionable
The people that died were highly paid professionals. Surely, they all had well above average on the job death benefits and compensation packages plus life insurances.
The people that died were highly paid professionals. Surely, they all had well above average on the job death benefits and compensation packages plus life insurances.
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That brief summary points to strap / buckle failure.
It appears that the investigators were able to sort out the failure modes before and after impact of the restraint system for the cargo.
Considering thet fire after impact, that's a tall order. Tough job.
Hopefully something with a bit more detail will be available soon.
It appears that the investigators were able to sort out the failure modes before and after impact of the restraint system for the cargo.
Considering thet fire after impact, that's a tall order. Tough job.
Hopefully something with a bit more detail will be available soon.
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I would still like to hear from the sources and see some of the data from the "black boxes" to see how it happened
I am sure that lead them to concentrate on the failure modes of the restraint system.
five vehicles, cut straps
My copy of this morning's New York Times National edition has a much longer article based on statements attributed to Nangialai Qalatwal, spokesman for Afghan Ministry of Transportation and Civil Action, presumably based on the same "press conference". Some points of possible interest:
1. The cargo is described as including three armored vehicles and two mine sweepers, totalling almost 80 tons.
2. It is stated that parts of the plane broke off and were left on the runway.
3. It is stated that the "charred remains of the cargo straps were recovered from the site and appear to have been cut", but that it was unclear whether that damage had occurred before or after takeoff.
The article is posted online at: NYTimes Bagram crash update but is probably behind a pay wall which may block your access.
1. The cargo is described as including three armored vehicles and two mine sweepers, totalling almost 80 tons.
2. It is stated that parts of the plane broke off and were left on the runway.
3. It is stated that the "charred remains of the cargo straps were recovered from the site and appear to have been cut", but that it was unclear whether that damage had occurred before or after takeoff.
The article is posted online at: NYTimes Bagram crash update but is probably behind a pay wall which may block your access.
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Numero1, that is either the most naive or obtuse thing I have read on pprune. The pressure on everyone's pay sheet is immense. I would be surprised if National Cargo's pilots are as highly paid as you imagine they are. I do not doubt that they were highly professional airman who just got unlucky. With the rates of pay at some organizations, I would not be surprised if there was not enough for niceties like extra insurance etc at the end of the month.
That said, I do stand to be corrected on the state of National's pay rates.
That said, I do stand to be corrected on the state of National's pay rates.
Numero1 - jetblu, the memorial page is an honorable tribute however I find the request for donations questionable
The people that died were highly paid professionals. Surely, they all had well above average on the job death benefits and compensation packages plus life insurances.
The people that died were highly paid professionals. Surely, they all had well above average on the job death benefits and compensation packages plus life insurances.
At the top of the National pay scale a Captain would have a gross flight pay of $142,000 per annum if he flew 70 hours per month. A mid seniority F.O. would earn $ 88,000 for the same flying. Their retirement is minimal and mostly self funded.
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An update on Avherald:
Crash: National Air Cargo B744 at Bagram on Apr 29th 2013, lost height shortly after takeoff following load shift and stall
On Jun 2nd 2013 accident investigators by the Ministry of Transport and Civil Aviation of Afghanistan reported in a press conference that quickly shifting cargo, consisting of three armored vehicles and two mine sweepers totalling at 80 tons of weight, caused the accident. The cargo slammed so hard at the back of the aircraft, that parts of the aircraft separated and wiring in the back was severed. As result of the shift and loss of aircraft parts the center of gravity moved so far back, that the attitude of the aircraft could no longer be controlled, the nose of the aircraft rose beyond the flying envelope of the aircraft and the aircraft stalled destroying the aircraft and killing all crew in the resulting impact. Parts of the aircraft, that separated as result of the initial load shift, were recovered from the runway. The straps used to tie down the cargo were recovered from the accident site, although charred they provided evidence of having fractured before final impact, it was unclear however, whether the fracture(s) had happened before or after takeoff.
The FAA had released a Safety Alert for Operators on May 20th 2013 regarding securing heavy vehicles in aircraft, see News: FAA concerned about potential safety impact of carrying and restraining heavy vehicle special cargo loads.
Crash: National Air Cargo B744 at Bagram on Apr 29th 2013, lost height shortly after takeoff following load shift and stall
On Jun 2nd 2013 accident investigators by the Ministry of Transport and Civil Aviation of Afghanistan reported in a press conference that quickly shifting cargo, consisting of three armored vehicles and two mine sweepers totalling at 80 tons of weight, caused the accident. The cargo slammed so hard at the back of the aircraft, that parts of the aircraft separated and wiring in the back was severed. As result of the shift and loss of aircraft parts the center of gravity moved so far back, that the attitude of the aircraft could no longer be controlled, the nose of the aircraft rose beyond the flying envelope of the aircraft and the aircraft stalled destroying the aircraft and killing all crew in the resulting impact. Parts of the aircraft, that separated as result of the initial load shift, were recovered from the runway. The straps used to tie down the cargo were recovered from the accident site, although charred they provided evidence of having fractured before final impact, it was unclear however, whether the fracture(s) had happened before or after takeoff.
The FAA had released a Safety Alert for Operators on May 20th 2013 regarding securing heavy vehicles in aircraft, see News: FAA concerned about potential safety impact of carrying and restraining heavy vehicle special cargo loads.