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Old 22nd October 2016, 19:52   #406
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Default Re: Boeing 777 - Pilot's Review

So I was hanging out with some of my pilot colleagues a few days ago. We were discussing this Incident: China Eastern A333 at Shanghai on Oct 11th 2016, runway incursion forces departure to rotate early and climb over A333.

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A China Eastern Airbus A330-300, had landed on Hongqiao's runway 36R and was taxiing to the terminal needing to cross runway 36L. The aircraft, that had been previously cleared to cross runway 36L, was instructed to stop and hold short of runway 36L but did not react to the stop instruction.

A China Eastern Airbus A320-200, was accelerating for takeoff from Hongqiao's runway 36L when at about 110 KIAS the crew spotted the A330-300 crossing the runway edge and assessed that they would not be able to stop in time to avoid a collision, however, they would be able to outclimb the A330. The crew firewalled the engines, continued their takeoff run, rotated the aircraft at about 130 KIAS and managed to climb the A320 over the A330. The A320 continued to Tianjin for a safe landing about 100 minutes later.

China's Civil Aviation Authority CAAC reported that the A320 was in their takeoff run when the A330 crossing the runway appeared in front of them. The A320 captain assessed that it was safer to continue, the rest of the flight was without further incident. An investigation into the serious incident has been opened. On Oct 12th 2016 the CAAC reported that preliminary investigation results suggest the serious incident was caused by a tower controller's misdirected instruction.
To the commercial pilots out here, what would you have done? And why? And would you comment on the decision taken by the crew?
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Old 22nd October 2016, 23:02   #407
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I am no pilot, but if I could, I would have done the same. I am sure all other pilots would have done the same too.

The article clearly says there was no other option. The take off could not have been aborted without causing a collision. So deciding to continue and fly over the crossing plane was actually a forced choice.

If I also read the report correctly, the rotation of the plane means the pilot did not take off in a straight line, quite possibly deciding to avoid the tail portion of the crossing plane. In my opinion the pilot showed excellent judgement and nerve.

PS: I checked a simulation of the incident on YouTube and the departing plane seems to have taken off in a straight line, but at a steeper climb rate. Result of firewalling the engines, I suppose.

It would be interesting to see what the pilot of the departing plane would have done if he had determined that the take off could be aborted safely. Then it would be judged very risky if he had decided to still fly over the plane.

Last edited by honeybee : 22nd October 2016 at 23:22.
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Old 23rd October 2016, 01:48   #408
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Originally Posted by Ayesha View Post
So I was hanging out with some of my pilot colleagues a few days ago. We were discussing this Incident: China Eastern A333 at Shanghai on Oct 11th 2016, runway incursion forces departure to rotate early and climb over A333.
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Originally Posted by honeybee View Post
I am no pilot, but if I could, I would have done the same. I am sure all other pilots would have done the same too. The article clearly says there was no other option. The take off could not have been aborted without causing a collision. So deciding to continue and fly over the crossing plane was actually a forced choice.
As you might have noticed, being a FO of a long-haul airliner, I usually do not comment & speculate over actions/decisions taken by my fellow pilots. It is very easy to do this sitting in front of a computer, when you were not present over there. But in this instance, I will have to make an exception. This has been the topic of discussion at my company for the last week, and most of us agree that the decision to keep flying was wrong.

First, let's briefly go over what happened(data from avherald)

I have attached a map of the airport, which will help you in understanding the incident better. Again, chart has been edited out to make things simple for the average reader to understand. Read from the bottom.
  • There were two aircrafts involved in this incident, an A320 and another A330.
  • The A320, a small aircraft with 146 passengers, was taking off runway 36L, (highlighted by the blue text at the bottom.)
  • The A330, a bigger aircraft, with 266 passengers, had landed on runway 36R and was taxiing to the terminal needing to cross runway 36L.
  • When the A320 was just short of taxiway H4, 2530 feet short of taxiway H3, the A333 was taxiing on taxiway H3 and crossed the right runway edge.
  • At about 110 KIAS the crew spotted the A330 crossing the runway edge and assessed that they would not be able to stop in time to avoid a collision, however, they would be able to outclimb the A330.
  • The crew firewalled the engines, continued their takeoff run, rotated the aircraft at about 130 KIAS and managed to climb the A320 over the A330.
  • The A320 became airborne abeam taxiway C2 1000 feet short of taxiway H3, and cleared the A330 by 62 feet.

Some significant points to note.
  • V1 = 146 KIAS
  • VR = 147 KIAS
  • V2 = 151 KIAS
  • Calculations show that had the A320 rejected takeoff at H4, it would've stopped 700 feet short of the A330.
  • The F/O, on spotting the A330, braked for a second, before the captain overruled his decision and decided to continue.

What do I think of this episode?

To most people, at first glance, it appears that the decision taken by the captain to continue with the takeoff was correct. And with a result like that, it certainly appears to be so. But dig a bit deeper and things change a bit, at least from a pilot's perspective. I know that the decision to continue proved to be a working solution. But this does not mean that it was correct. As stated before, the calculations clearly show that had the A320 rejected takeoff at H4, it would've stopped 700 feet short of the A330. But some people say that the captain did not have any such calculations, it was a split second decision for him. I tend to disagree.

Why the decision to keep flying on was wrong?
  • The A320 was at 110 knots, around 36 knots below V1. Knowing that accelerating to the rotation speed would take 8-10 s, it was extremely risky to continue since it would've to be an early rotation.
  • What if the captain misjudged the situation. Height over threshold, the height of the A330's tail fin, distance lost during line up etc.
  • What if there was a tail strike?
  • What if one of the overstressed engines you just firewalled quit right at rotation?
As someone commented, attempting the takeoff had only two options, clear climb out or high speed collision. The difference between eye-balling it and killing hundreds through overconfidence was just 20 meters. There was no guarantee that the aircraft would perform flawlessly. But they were at 150+ kts heading straight for the A330. And if anything had gone wrong, anything at all (remember, possible stall, possible thrust issue, possible tail strike, etc), it would've been Tenerife all over again.

Why the decision to reject takeoff would've been a better/safer option?

Broadly speaking, there would've been four possibilities had the crew rejected the takeoff.
  • Best case: A330 clears the runway by the time the A320 reaches H3.
  • Best case: High speed turn off at taxiway B7.(At around 50 knots).
  • Average case: Low speed excursion. The aircraft would've been damaged and some people would have bruise, but that would be it.
  • Worst case: Low speed collision, with very little damage.

When we pilots fly aircrafts, we shoulder a big responsibility of the lives of hundreds of passengers. And it for this specific reason that we do not take risks. It is for this reason that we do not eye-ball things. It for this reason that we have written checklists. It for this reason that we follow SOPs. While this was and with a positive outcome this time, we could just as well be reading about 400 dead, had they struck the cabin of the 330, or 150 dead had they left half of their right wing hanging from the 330's tail.

So, to conclude, I believe that while the decision taken by the captain to overrule the F/O and continue the takeoff was bold, it was rash and a seat of the pants decision. It could've resulted in a disaster. The safer option in this case would've been to reject take-off.
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Old 23rd October 2016, 08:50   #409
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Default Re: Boeing 777 - Pilot's Review

Interesting read: AI now flies the Pacific route from Delhi to SFO, and the Atlantic route from SFO to Delhi, thus completing a round-the-globe trip.

http://timesofindia.indiatimes.com/i...w/55005821.cms

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The Pacific route is almost 1,400km longer than the Atlantic one, and the flight covered 15,300 kilometres in 14.5 hours. Despite the route being longer, the flight took almost two hours less thanks to tailwinds ó winds that blow in the same direction as an aircraft and thus make it go faster.
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The Boeing-777 200 long range used by AI on this route, on an average, burns 9,600 litres of fuel for each hour of flying. A shorter flying time on the Delhi-SFO route ó from an hour in summer to three hours (in winter) ó would mean huge fuel savings for the airline.
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Old 23rd October 2016, 11:06   #410
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Originally Posted by searchingheaven View Post
To most people, at first glance, it appears that the decision taken by the captain to continue with the takeoff was correct. And with a result like that, it certainly appears to be so. But dig a bit deeper and things change a bit, at least from a pilot's perspective. I know that the decision to continue proved to be a working solution. But this does not mean that it was correct. As stated before, the calculations clearly show that had the A320 rejected takeoff at H4, it would've stopped 700 feet short of the A330. But some people say that the captain did not have any such calculations, it was a split second decision for him. I tend to disagree.

So, to conclude, I believe that while the decision taken by the captain to overrule the F/O and continue the takeoff was bold, it was rash and a seat of the pants decision. It could've resulted in a disaster. The safer option in this case would've been to reject take-off.
Thanks, very interesting perspective. Iím of the generation that remembers the Tenerife disaster very well. Iím also Dutch so it was in the news at the time for weeks in the Netherlands and my dad, as a lawyer, got involved in the legal after math. This could have easily turned into something very similar.

I have followed this one on PPruNE (http://www.pprune.org/rumours-news/5...-shanghai.html)

As you say, just because the decision to continue the take off worked out fine, doesnít mean it was the best decision. Remarkably, I have seen a lot of comments around the net, even from pilots, that claim it was the correct decision for no other reason it worked.

A lot of comments are floating around that, yes calculations show they should have been able to come to a full stop with several hundred feet to spare. Of course, couple of hundred feet as a margin when you are barreling down the runway at 110 knots isnít much. But somehow this captain believed continuing the take off would give him a better chance at clearing the A330 with, one would assume, more margin!

It was truly one of those split second decisions, they donít come much tighter. So they managed to get of the ground, no harm done. (Except some spoiled underwear I would image!) But it does look as if stopping would have been the better option.

Just wondering? Yes, a pilot should be familiar with all handling characteristics of his/her plane, including max braking. But how often do you get to do a max braking? What Iím saying, but itís just a thought, purely from a Ďgained experience over the yearsí are (commercial) pilots more familiar with a (close to) max power take off scenario then a max braking scenario? Itís easy to see how that could affect/cloud the captain's judgement in this situation. Not making excuses, just trying to figure out what went on his mind, what criteria and or experience, insights did he use to come to this decision.

On my little planes we always use full power to take off (no derating , but rarely would I land using max braking. I know exactly how the plane feels at a full power take off, what sort of acceleration I will see for different loading scenarioís, how quickly should we eat up the runway etc. But I have no such set of experiences for max braking. Other then the odd training scenario and a few actual short field landings.



Jeroen
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Old 23rd October 2016, 14:14   #411
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Thanks SearchingHeaven for the raw statistics. Not being a pilot I completely ignored that most important part in decision making: data or facts.

I simply assumed that the pilot had done these calculations and decided that the take off could not be aborted safely, but your data puts a different, and a most logical, perspective to the episode.
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Old 23rd October 2016, 18:35   #412
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Originally Posted by Strella View Post
By the way, once you program the FMC there are multiple things that you monitor as your flight progresses. Also, on the ground the FMC is programmed by one pilot, mostly the First Officer and then cross checked with the paper CFP( computerised flight plan) by the other pilot.Once this cross check tallies , most of your programming is done. There are multiple crosschecks. The FMC itself is a sophisticated piece of hardware, taking inputs from 2 independent GPS, 2 independent IRS, and multiple ground based beacons en route.( Besides being monitored at most times by our friends on the ground with their very accurate radars, the ATC).
What if the FMC fails in an oceanic region where there is no radar coverage? By the way, the FMC is not a system that is certified for the highest design assurance level in an airplane. Why isn't an FMC certified to the highest design assurance level (unlike a fly by wire system) ? Because the failure of an FMC is not supposed to cause a catastrophic failure of the airplane. Again why? because the pilots are supposed to be reasonably able to monitor FMC's navigation, recognize when there is a significant error and manually navigate from then on. Hence the ability of the pilot to manually navigate is non negotiable.
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Old 26th October 2016, 11:59   #413
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Originally Posted by Strella View Post
The world has moved on. By the way, once you program the FMC there are multiple things that you monitor as your flight progresses. Also, on the ground the FMC is programmed by one pilot, mostly the First Officer and then cross checked with the paper CFP. Once this cross check tallies , most of your programming is done. There are multiple crosschecks.

You may kindly check with other commercial pilots you know about how they brush up on their navigation skills. Except , the odd enthusiast , most of them should corroborate what I say.
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Because the failure of an FMC is not supposed to cause a catastrophic failure of the airplane. Again why? because the pilots are supposed to be reasonably able to monitor FMC's navigation, recognize when there is a significant error and manually navigate from then on. Hence the ability of the pilot to manually navigate is non negotiable.
Hi Strella,

I think I will have to go with Jeroen and minivandriver here. While modern planes do have complicated FMC's which can do all of the navigation at an abstract level, pilots are still required to monitor the aircraft's position closely. If there is a dual FMC failure, we are required to inform the ATC about degraded navigational performance/unable LNAV/VNAV and navigate using the primary navigation methods like magnetic heading, VOR's etc.

Navigation using just FMC is like studying engineering without studying science in high school. You may be able to do it on a higher level, but your basics will be very weak. And if there is a problem which requires these basics, you will be left in a lurch.

Quote:
Originally Posted by Jeroen View Post
Just wondering? Yes, a pilot should be familiar with all handling characteristics of his/her plane, including max braking. But how often do you get to do a max braking? What Iím saying, but itís just a thought, purely from a Ďgained experience over the yearsí are (commercial) pilots more familiar with a (close to) max power take off scenario then a max braking scenario? Itís easy to see how that could affect/cloud the captain's judgement in this situation. Not making excuses, just trying to figure out what went on his mind, what criteria and or experience, insights did he use to come to this decision.
Max manual braking or A/B Max is very rarely used in real life scenarios. I, personally and my company SOP recommendation is to use Auto brake 3 for most scenarios. In some special airports and situations like Birmingham, we use Auto brake 4, which can kick in quickly and savagely, sometimes also causing the nose to dive in deep.

In real life, I have had a rejected take off only once, but at a low speed of around 75 knots. The RTO autobrakes hadn't armed, so we had to disarm the Autothrottles and then reduce thrust, apart from arming the speed brake and braking manually. This RTO was caused due to a miscommunication between the ATC and us.

In simulators, we have practiced the RTO procedure many times, sometimes at 100 knots and sometimes at V1-10 knots. Both these scenarios required max braking. I have to say that the sim over exaggerates some effects. It generates too much of noise and vibration compared to real life.
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Old 26th October 2016, 13:47   #414
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Hello searchingheaven,

I am not trying to defend the indefensible. Of course, the basic skills should always be there. I am sure that you have not reached the 777 directly but must have worked your way up from smaller and less sophisticated aircrafts. It is mostly on the smaller/ simpler airplanes that the pilots build up their basic skills. Once the skills are built up they remain with you for a long time. However, once we move to more sophisticated airplanes these skills are not very often utilised thanks to the reliance(or over reliance) of all the available automation. I am sure the professional pilots would be able to handle a dual FMC failure and navigate the big bird using the basic available information.

I would also go with minivandriver and agree with what he says.
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Old 27th October 2016, 00:41   #415
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Quote:
Originally Posted by searchingheaven View Post
In simulators, we have practiced the RTO procedure many times, sometimes at 100 knots and sometimes at V1-10 knots. Both these scenarios required max braking. I have to say that the sim over exaggerates some effects. It generates too much of noise and vibration compared to real life.
I have done a few max braking execercises in the 744 simulator and it is quite spectacular.


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Originally Posted by Strella View Post
Once the skills are built up they remain with you for a long time. However, once we move to more sophisticated airplanes these skills are not very often utilised thanks to the reliance(or over reliance) of all the available automation. I am sure the professional pilots would be able to handle a dual FMC failure and navigate the big bird using the basic available information.
Actually, those skills do not remain with you at all. Whether it is stick and rudder skills or navigation skills, flight planning or anything else. You need to practice, you need to practice regularly there is no other way about it.

A lot has been said and discussed the last few years of (commercial) pilots losing their stick and rudder skills as they rely heavily on automation and only fly manual a few minutes per month. But the same is true for manual navigation. If you don’t practice it often, when the automation breaks down you will find yourself behind the curve very quickly! This phenomena is not unique to aviation. Other industries that rely heavily on automation (e.g. oil, chemical, power plants) have the same issue. Monitoring the automation doing its ob and actively stepping in at a moments notice and taking manual control is not something humans are particularly good at. (this, by the way is one of the problems with autonomous cars). So you need to train all manual skills constantly, repeatedly!

Remarkably, the so often quoted flight hours as a measure of experience/competence is completely fake. Just check the last one or two decades of accidents with fatalities and you will find that in many cased very experience pilots (expressed in flight time) where at the control.

A lot of debate these days about young pilots and captains and that they don’t have enough experience. Again, I have yet to see any fundamental/basic research into correlation between age/flight time/ flight safety!

The only research I know of (I could be wrong, there could be more) is the FAA research into FAA accidents with fatalities.

The FAA research on General Aviation pilots found no correlation, none whatsoever, between number of flight time/hours and fatal accidents. To put it differently, a pilot with 10.000 hours has the exact same statistical chance of meeting with a fatal accident as low 100 hours pilot. Maybe counterintuitive, the unions did not like it, quite a few pilots high on the seniority and promotion lists did not like it, but that is what the data shows.

The data also showed that pilots who take a very active stance in continuous developing and honing their overall skills have a much lower accident rate. Hence the FAA Wings program. Pilots participating in this program have a 50% lower chance of a fatal accident than non participating pilot. The remarkable thing is this program takes place in class rooms, not in the cockpit, let alone in flight. It’s all about talking about risk management, recognising risk, etc. It’s not about stick and rudder skills. It’s about all those other skills a great pilot needs in order not to have to rely on exceptional stick and rudder skills.

Pilots that take an active approach on keeping current with old school navigation techniques are much more likely to complete a flight with navigation equipment issues successful then those who take a passing interest. Same for any topic under the sun. It’s just how humans work. To think differently is a sign of poor insights and does not suit a pilot at all.

I would love to hear/see some more information on how carriers rate their pilots performance! Most of us have some sort of performance review a few times a year. Usually it ends up with some summary as underperforming, partial performing, meets expectations, excellent, outstanding. Or whatever the scale is. How do carriers rate their pilots and what are the criteria? What fundamental research has been used to come up with the system.

My insurance company gave me a big discount on the various Wings Levels I achieved! In essence the FAA will tell you it’s all about attitude and continuous interest to better yourself to make a better (i.e. safe) pilot.

I always made it a rule to hone all my regular/manual skills next to all the skills required to run a fully automated flight. So I keep track of my flight planning and flight progress separately from the the various onboard systems. It’s also a great way to create situational awareness. You don’t get that looking at one screen. You get that by looking at different instruments, charts, and combining different data to complement an overall picture.

When I sail my Yachts across the seas/oceans I do the same. These days, yachts have more electronics then airplanes. And I love it. Still I always keep a running plot on a paper chart next to various electronic moving maps and GPS driven screens. I might be an old git, but I’m never lost and no matter what systems go down I can keep going without a moment hesitation.

I’m also old school (some might say old git) on how I think/feel humans learn. I am a great believer in the classic type of education. Where you learn the basic before going to the overall picture. So that’s why I like to understand navigation at it’s very basic. If you can navigate with a paper chart, slide rule, tables, pen and paper and maybe a sextant, I believe you are better prepared and have far superior insight into how for instance a FMC/FMS system works. Despite my love for a sextant these electronic system don’t intimidate me. I have been involved in the design of rocket guidance systems some time ago. I know more about GPS then most and the same is true for the Boeing/Honeywell FMS system. Although, admittedly a bit dated by now.

Most pilots might believe the position on the ND is, under normal circumstance a GPS position. Because that is what your AOM is telling you. And from a functional level that might be adequate. But it might well not be true actually. It could well be an augmented GPS postion. I enjoy navigation so I drill down into these system at a much lower level and spend many happy hours with some KLM maintenance engineers picking the 744 FMS systems apart in a hangar in Schiphol.

So fair to say I’m very happy with modern glass cockpits as it is so much easier to point my sextant to the stars!

Your remark about your believe that the professionals will handle a dual FMC failure competently has been proven to be wrong multiple times. Some do, some don’t. Some screw up spectacularly! http://avherald.com/h?article=482f868f&opt=0

Jeroen

Last edited by Jeroen : 27th October 2016 at 00:48.
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Old 27th October 2016, 13:54   #416
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Hello Jeroen,

Well, the above post is quite nicely put. I am sure most of us would agree with most of what you have mentioned. Practice is something that all us have to do regularly to remain current and competent in any sphere of work that we do.

One point I wish to add to is that there is no substitute for experience. The co-relation between experience and accidents may be true, but nothing teaches you more than experience. The problem sometimes with experience in some people is that it makes them complacent and at times arrogant , in thinking that they have seen it all and know all. Just like any other profession a good Captain/ Pilot is always willing to learn and be willing to be corrected. Learning is a never ending chapter which goes on your entire career.

It is obvious from your posts, that you have very good in-depth knowledge regarding some of the systems, which is more than what an average line pilot would know or need to know.

Regarding the incident mentioned above, what can be learnt is that the crew made an error in punching in the wrong co-ordinates, but the bigger mistake was not catching that mistake on the ground itself when they got various opportunities to do so. On almost all the parking bays/ gates you have the latitude and longitude mentioned just below the gate number and is an easy way to cross check your position vis a vis what is there on the FMC. in my company they do not encourage you to manually enter the position but rather copy it from the last position stored on the FMC.

https://en.wikipedia.org/wiki/Varig_Flight_254

I have mentioned the link to one of an interesting flight in which the pilots messed it up big time. So, getting a little wrong with the digits can have drastic consequences at times.
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Old 28th October 2016, 08:56   #417
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OMG.....a little mistake with horrible consequences. That Varig flight was not tracked by ground controllers at departing airports (or in between) due to so much deviation from flight plan? Do the ground controllers even have flight plans for all airplane in their area?
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Old 28th October 2016, 10:11   #418
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Goes to show the importance of following the SOP to the letter. If the co pilot had not copied the settings, the error would be discovered before take off.

Also underlines the need to have and use experience. Didn't the pilot realise the heading was odd? The route doesn't change everyday, so the flight plan heading of 270 degrees should have forced the pilot to stop and check if there was something amiss. Even with the old notation the heading had a huge difference in value.

Finally I can understand that flight levels are abbreviated to hundred feet probably for brevity, so 340 means 34000, but why headings should be printed as 0270 and not 027.0? Especially when it's confusing?
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Old 28th October 2016, 11:19   #419
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Default Re: Boeing 777 - Pilot's Review

Very interesting reply searchingheaven!

I don't have the understanding nor the data to have an opinion on this as yet.

However, what I want to know is:

Quote:
Originally Posted by searchingheaven View Post
As stated before, the calculations clearly show that had the A320 rejected takeoff at H4, it would've stopped 700 feet short of the A330. But some people say that the captain did not have any such calculations, it was a split second decision for him. I tend to disagree.
What makes you imply the pilot did have some calculations like this? Is it a normal thing to have, or something he should be trained to do in his head?

Also (referencing the armchair comments point), could there be other factors being overlooked by everyone discussing this? Could it have taken a while for the pilots to spot the other plane / be aware that it was definitely a collision course?


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Originally Posted by Jeroen View Post
What I’m saying, but it’s just a thought, purely from a ‘gained experience over the years’ are (commercial) pilots more familiar with a (close to) max power take off scenario then a max braking scenario? It’s easy to see how that could affect/cloud the captain's judgement in this situation.
Excellent point!

"A known devil is better than an unknown angel"...
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Old 28th October 2016, 12:49   #420
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What makes you imply the pilot did have some calculations like this? Is it a normal thing to have, or something he should be trained to do in his head?
Hi Rehaan,

I did not mean that the pilot should have/could have done those calculations in his head. It is not humanly possible to do so in the 5 seconds that he had. What I mean is that once you start flying a certain aircraft, you get an idea of how the aircraft behaves over time, both in terms of take-off roll acceleration and braking performance at varying weights. And as a captain, he would have been flying that aircraft for well over 10,000 hours. So in general, with that kind of experience, he would've known that his aircraft would have stopped in time. Even a split second estimate would have told him that rejecting the takeoff would've been a much safer option.

This fact is highlighted by the height clearance when the A320 climbed over the A330. Believe me, for an aircraft the size of A330, 60 ft of clearance is simply too less. There was no margin for error. If anything had gone wrong or if there was a two second delay, we would be looking at the biggest air disaster of our times.

Quote:
Originally Posted by Rehaan View Post
Also (referencing the armchair comments point), could there be other factors being overlooked by everyone discussing this? Could it have taken a while for the pilots to spot the other plane / be aware that it was definitely a collision course?
No problem with visibility as such. Regarding the pilot of the A320 being aware of the A330, I think that the A320 must've noticed the A330 taxiing much before H4. As they reached H4, they realized that the A330 had crossed the stop bar of the runway crossing threshold and would be coming directly into their path. Once an aircraft crosses the stop bar and the runway threshold, it can be distinguished from an aircraft which is holding before the threshold very clearly.

Quote:
Originally Posted by Jeroen View Post
What Iím saying, but itís just a thought, purely from a Ďgained experience over the yearsí are (commercial) pilots more familiar with a (close to) max power take off scenario then a max braking scenario? Itís easy to see how that could affect/cloud the captain's judgement in this situation. Not making excuses, just trying to figure out what went on his mind, what criteria and or experience, insights did he use to come to this decision.
Well, to be frank, even max power take-off are as rare as max braking scenarios. Most takeoffs, i.e around 95% are derated takeoffs, i.e we takeoff at around 91% to 95% N1 to prolong engine life. IIRC, I have only firewalled throttles once in the last year, when we saw a flock of birds at the far end of the runway and decided to rotate early. I can easily say that I have braked at max more than once. Slippery runways, we use Autobrake 4 setting, which is close to max braking. And we use it once in a month at least.
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