[balenoed_]

Originally Posted by Rahul Bhalgat

From the posts of the experts Searchingheaven and Jeron, it appears that the aircraft lost lift because of windshear.

Yes sure, got that. I was just speculating that since the aircraft did not fall of the sky on the final approach (moments before touch down) like the Delta Airlines 191, nor did it lose lift drastically or stall (as per eye witness), but managed to touch down the runway on its wheels without crashing and exploding, why was there a purpose to go-around. May be I am thinking too naive about this and there is much more to do with all this.

Leaving it to the experts here to throw some light.

[kutts]

Originally Posted by searchingheaven

And maybe it's irrelevant to this discussion, but I noticed that 3rd Aug was the first day EK521 was flown with a 777-300. Earlier, the A330-200 was being used in this sector. On 4th Aug i.e the next day of the accident, Emirates replaced the 777-300 with a 777-300ER. Can 2+2 be equal to 4? To quote Frederick Forsyth, the trouble is, in the world of shadows and distorting mirrors, what may or may not appear to be two, when multiplied by a factor that may or may not be two, could possibly come out at four but probably will not.

The flight stats are incorrect since I was on EK521 on 16thJul and it was a 777. It used to be 330 generally, but there was an aircraft change. So we can safely rule out that angle

[Jeroen]

Originally Posted by balenoed_

Yes sure, got that. I was just speculating that since the aircraft did not fall of the sky on the final approach (moments before touch down) like the Delta Airlines 191, nor did it lose lift drastically or stall (as per eye witness), but managed to touch down the runway on its wheels without crashing and exploding, why was there a purpose to go-around. May be I am thinking too naive about this and there is much more to do with all this.

Leaving it to the experts here to throw some light.

Honestly, at this point in time I don't think anybody has a clue what happened. Even the usual aviation forums don't provide any clarity.

[petrolhead_chn]

Originally Posted by kiku007

Some flight attendants don't even stop them anymore. They just let the chaos continue because educated or not people are trained not to listen to instructions.

If what you say is true, then you have brutally criticised the entire community of crew members/air transport staffs. In my opinion, crew members are calm, dedicated and composed enough to handle almost any type of passenger and situation. They put their life before their passengers. I regret to share that your statement is bland or maybe I did not comprehend correctly.

Originally Posted by kiku007

What if even a single life within the aircraft was lost because of delays caused by luggage grabbing? Would we still dismiss it because of first time flyers or "to each their own preciousness"?

Well, it certainly did not happen in this case and I suppose those precious lives were saved only because of those 'calm, dedicated and composed enough' crew members who handled the situation pretty well amidst those 'luggage grabbing' situations. So I'm sure none of the crew member inside that aircraft let the chaos continue. They did their best amidst chaos. Kudos to them!!!

Originally Posted by kiku007

A flight has crash landed and if that can't make value their lives more than their luggage, I don't know what will.

Again, easier said than done. I certainly do not wish to pick up a debate here nor I am opposing the statements. I am only trying to communicate that 'luggage grabbing' or any 'other unrelated activity' (in a broad spectator's view) in such situations is only a series of unconscious/natural reaction/response by any human being.

Rest assured, all those people are saved. Thank God and all those involved in the evacuation process.

[norhog]

There were three 777( including this Emiratres one) that was involved in crash during landing.
BA 777-200ER with RR engines at Heathrow in 2008 Jan.
Asiana Airways 777-200ER with PWengines in 2013 July.
Emirates 777-300 with RR Trent engines at Dubai.
Now two of them were running RR engines.
I am not a conspiracy theorist but two of them were running RR engines, is a common thing. Anything more in common here.
Sorry if this seems like a very amateurish attempt at air crash investigation.
Also the explanation regarding ice, for BA crash seems unlikely to me. That is because ATF is a very refined variety of petroleum product with almost nil water content. This is just general information, the experts here may please guide weather this holds any, well "water".
Can the experts please give their opinion on this line of thought.

[Jeroen]

Originally Posted by norhog

Sorry if this seems like a very amateurish attempt at air crash investigation.

Can the experts please give their opinion on this line of thought.

Don’t give up the day job yet. You are a long way from being an air crash investigator.

Just because two planes share the same power plant doesn’t mean anything as we haven’t a clue what happened. They also share the same Honeywell Flight Management System, the same hydraulics etc etc. They were both built in Seattle

Feel free to question the real Investigators of course!?

https://en.wikipedia.org/wiki/British_Airways_Flight_38

Jeroen

[kiku007]

Do you work for Times News/Times of India by any chance? Because only they are well known for twisting this,

Originally Posted by kiku007

While not everyone would have been frequents flyers, the practice of grabbing luggage from overhead compartments while the flight is taxing is like a disease in India. And this is done by majority of the people regardless of their flying history. Some flight attendants don't even stop them anymore. They just let the chaos continue because educated or not people are trained not to listen to instructions.

as this,

Originally Posted by petrolhead_chn

If what you say is true, then you have brutally criticised the entire community of crew members/air transport staffs. In my opinion, crew members are calm, dedicated and composed enough to handle almost any type of passenger and situation. They put their life before their passengers. I regret to share that your statement is bland or maybe I did not comprehend correctly.

If you can’t comprehend, ask before going overboard with your assumptions. I used pretty straight forward language.

Originally Posted by petrolhead_chn

I am only trying to communicate that 'luggage grabbing' or any 'other unrelated activity' (in a broad spectator's view) in such situations is only a series of unconscious/natural reaction/response by any human being.

Originally Posted by kiku007

While not everyone would have been frequents flyers, the practice of grabbing luggage from overhead compartments while the flight is taxing is like a disease in India. And this is done by majority of the people regardless of their flying history.

In case you didn’t get it. It’s not as if people picked up the luggage out of panic alone. It’s like part of the post landing ritual (Crash or normal landing or whatever).

[libranof1987]

Brilliant thread, searchingheaven!

The aviation knowledge being shared in this thread is mind-blowing; thanks for taking the time to post such detailed replies!

I'm curious: what is the maximum damage to the fuselage that can be repaired for the aircraft to be put back in service.

We've had panels come off planes mid-flight (Southwest), several instances of belly landings, tail strikes; surely they weren't hull losses.

During a documentary on the Dreamliner, I vaguely remember them mentioning that the composite compounds in the chassis made repairs more feasible.

As a pilot, what are the kind of past issues on a plane that you don't sweat about, and which ones do you fuss over?

[searchingheaven]

Originally Posted by libranof1987

Brilliant thread, searchingheaven! The aviation knowledge being shared in this thread is mind-blowing; thanks for taking the time to post such detailed replies!

Thank you for your appreciation.

Originally Posted by libranof1987

I'm curious: what is the maximum damage to the fuselage that can be repaired for the aircraft to be put back in service. We've had panels come off planes mid-flight (Southwest), several instances of belly landings, tail strikes; surely they weren't hull losses.

In general, there is a repair decision chart that is followed by MRO companies. I have attached an example which gives a rough idea. Procedures vary depending on the manufacturer, model, ship number, insurance company and the MRO company. Most big airports have good maintenance facilities. If an aircraft is at a smaller airport with no MRO, there is an AOG(Aircraft on ground) team which flies in to repair the damage. If they can patch it up enough to fly to a maintenance hanger, then it's fine. If not, then the part is flown in another aircraft.

Originally Posted by libranof1987

During a documentary on the Dreamliner, I vaguely remember them mentioning that the composite compounds in the chassis made repairs more feasible.

I think you might want to see that documentary again. Far from being feasible, composite compounds are a big problem from the point of view of maintenance, repair and overhaul (MRO). Maintenance requirements of composites are unlike those of metals and most MRO corporations do not have ample experience of maintaining composite structures. There is a lack of standardization regarding training certification, repair techniques, and materials. Compounding that problem is the fact that composite repair itself deploys up to 58 unique materials, while traditional metal repairs require only about a dozen. In addition, technicians are less likely to repair a composite correctly, since the quality of repairs depends primarily on which process they use.

Originally Posted by libranof1987

As a pilot, what are the kind of past issues on a plane that you don't sweat about, and which ones do you fuss over?

I was stuck in a microburst that dropped me 50 feet when I was about 200 feet above ground level. A couple bird strikes, and a landing gear failure. No crashes and none of the above was anything that my captain and I would not have been able to handle. As a rule of thumb, major equipment failures are very rare, especially in an aircraft as well-engineered as the 777.

[apachelongbow]

From all what I gathered about the sad Emirates crash landing, I understand that there are a couple of scenarios.
A) The aircraft landed hard, bounced, at the far end of the landing zone, the pilots elected to go around, aircraft climbed to about 100 feet, gear was commanded up, and then sank back to the runway, classic case being not enough power to generate sufficient lift post go around.
B) A micro-burst, or sudden wind shear especially during flare, which pushed the airplane hard into the ground and caused the bounce, subsequent shift in winds especially with the action of gear door opening (for landing gear retraction operation), the aircraft stalled at about 100 feet and crashed.

There is also a small doubt regarding the Boeing 777 automation which the thread starter can solve. As far as I understand for a 777 to perform a go around, the auto throttle must be fire-walled and the TOGA buttons pushed, to instruct the fmgc and the FD bar to perform the go around maneuver. If one accidentally pushes the TOGA buttons, but takes hands off the thrust levers, the airplane will command the thrust back to idle, giving rise to almost the situation the unfortunate aircraft found itself in. Also there seems to be some confusion regarding the exact auto pilot/auto thrust behavior during a bounced landing and subsequent go around. Some people claim that when the landing gear senses ground, the engines are inhibited from giving TOGA power for a 'x' number of seconds even if throttles are fire walled.

In any case we must appreciate the pilots, the cabin crew and the ground staff who did extremely well in handling a disaster and saved all 300 odd lives

[V.Narayan]

Originally Posted by libranof1987

I'm curious: what is the maximum damage to the fuselage that can be repaired for the aircraft to be put back in service.

Good question. The short answer is that aircraft can be rebuilt and repaired and put back into service after a lot of damage. More than one would normally believe. Airliners that crash landed (but did not catch fire in any major way) are often put back to service (and have been by the several dozens) and are known to have continued for years. Two famous examples were :


Japan Air Lines Flight 02 landing in shallow seas just short of the San Francisco runway in 1968. This Douglas DC-8 went onto fly in regular passenger (and then cargo) service till 2001.


Another very famous case was of the Gimli Glider in 1983 - an Air Canada Boeing 767 that landed at a deserted air strip after running out of fuel by gliding down from 35,000' (you read that right). This machine was put back in service and flew till 2008 with Air Canada as a passenger airliner. This case is a clear testimony to the skills and nerves of experienced well trained pilots.

Having said the above I would caution that such heavy repair has its risks even after working together with the OEM. The risk lies in microscopic cracks in a main structural part that cannot be detected and could gradually grow over time and merge up with other microscopic cracks that were initiated by the accident. But every main structural piece has one or more back ups through which the load/stress can pass. I would still say flying commercial is safer than crossing the road in any large Indian town! Military aircraft of course are routinely rebuilt and put back into squadron service.

Searchingheaven thank you for your detailed, lucid and patient answers on this most interesting thread. The quality of your answers raises the bar at Team BHP. Kudos.

[Jeroen]

Originally Posted by apachelongbow

There is also a small doubt regarding the Boeing 777 automation which the thread starter can solve. As far as I understand for a 777 to perform a go around, the auto throttle must be fire-walled and the TOGA buttons pushed, to instruct the fmgc and the FD bar to perform the go around maneuver. If one accidentally pushes the TOGA buttons, but takes hands off the thrust levers, the airplane will command the thrust back to idle, giving rise to almost the situation the unfortunate aircraft found itself in. Also there seems to be some confusion regarding the exact auto pilot/auto thrust behavior during a bounced landing and subsequent go around. Some people claim that when the landing gear senses ground, the engines are inhibited from giving TOGA power for a 'x' number of seconds even if throttles are fire walled.

Searching haven is the authority on the 777, but I would doubt very much you have to actually firewall the throttle. I’m reasonably familiar with the 747-400 and these system are very similar.

As long as you have auto throttle engaged and you push the TOGA switch the throttle will move forward. Most procedures I’m familiar with require the pilot to keep his/her hands on the throttle, but you just follow. As discussed earlier one push gets you plenty of thrust already, you need to get out of Dodge real fast you hit TOGA again.

As long as the throttles are firewalled, either by the automation or the pilot you will get full thrust. What is not always clear is at what point in time during the landing you can still use the automated TOGA function. On the 747 it is after touchdown or if the airplane is below 5 feet RA for more than 2 seconds. But the minute you shove those throttles into the firewall you will get full thrust. Not sure what happens to the FD in such a scenario though?

Over to searching heaven for the real answer!

Jeroen

[RVD]

Originally Posted by apachelongbow

There is also a small doubt regarding the Boeing 777 automation which the thread starter can solve. As far as I understand for a 777 to perform a go around, the auto throttle must be fire-walled and the TOGA buttons pushed, to instruct the fmgc and the FD bar to perform the go around maneuver. If one accidentally pushes the TOGA buttons, but takes hands off the thrust levers, the airplane will command the thrust back to idle, giving rise to almost the situation the unfortunate aircraft found itself in. Also there seems to be some confusion regarding the exact auto pilot/auto thrust behavior during a bounced landing and subsequent go around. Some people claim that when the landing gear senses ground, the engines are inhibited from giving TOGA power for a 'x' number of seconds even if throttles are fire walled.

NO. Just pressing TOGA is sufficient to get the GA mode. The thrust lever does not have to be fire-walled. Regarding bounce landing, there is no inhibit for TOGA power. You will get the thrust after the normal spool up time. What does happen ( At least on the 737) is that if the aircraft senses ground mode for more than 2 seconds, the AT disconnects. As long as the ground contact is for less than 2 Sec, the AT will command GA power once TOGA is pressed. The TOGA mode is inhibited on a FAIL OPERATIONAL autoland after touchdown to prevent inadvertent engagement. For all other times, you will get GA thrust when TOGA is pressed.

Originally Posted by Jeroen

Searching haven is the authority on the 777, but I would doubt very much you have to actually firewall the throttle. I’m reasonably familiar with the 747-400 and these system are very similar.

As long as you have auto throttle engaged and you push the TOGA switch the throttle will move forward. Most procedures I’m familiar with require the pilot to keep his/her hands on the throttle, but you just follow. As discussed earlier one push gets you plenty of thrust already, you need to get out of Dodge real fast you hit TOGA again.

As long as the throttles are firewalled, either by the automation or the pilot you will get full thrust. What is not always clear is at what point in time during the landing you can still use the automated TOGA function. On the 747 it is after touchdown or if the airplane is below 5 feet RA for more than 2 seconds. But the minute you shove those throttles into the firewall you will get full thrust. Not sure what happens to the FD in such a scenario though?

Over to searching heaven for the real answer!

Jeroen

You can use TOGA on landing till the AT disengages(Around 2 seconds after Touchdown. If you just firewall the throttles, you would not get FD guidance but anytime that TOGA is pressed, the command bars will start providing correct guidance. You also get FD guidance upto a certain altitude if TOGA is pressed, even if the FD bars are turned off. Please note that the FD logic is different for a normal GA and a windshear GA.

[Jeroen]

Originally Posted by RVD

Please note that the FD logic is different for a normal GA and a windshear GA.

Could you elaborate a bit on the difference between these two?

I’m sort of familiear with the PWS (Predictive Windshear System) on Boeings, but I understood it to provide an alarm/warning only. It doesn’t do anything to the actual TOGA modus operandi I believe, including FD logic? Maybe my documentation is getting outdated though!

Jeroen

[RVD]

Originally Posted by Jeroen

Could you elaborate a bit on the difference between these two?

I’m sort of familiear with the PWS (Predictive Windshear System) on Boeings, but I understood it to provide an alarm/warning only. It doesn’t do anything to the actual TOGA modus operandi I believe, including FD logic? Maybe my documentation is getting outdated though!

Jeroen

During Takeoff and GA, if windshear is encountered, FD pitch command attempts to maintain the target speed. In the process of doing so, If the rate of climb reduces to below 600FPM then the FD commands 15 Degree pitch up. If the climb rate continues to decrease then the FD continues to command 15 degree pitch up until the speed corresponding to stick shaker is reached. It then commands pitch attitude which results in intermittent activation of stick shaker.

Please note that this is the logic on the 737 but I don't believe that it would be too different on the 777.