@Noble: did you actually read the report? Do you know why the tail strike actually occurred? Do you know why they did NOT go through the ILS antenna that was waiting to shred the aircraft into a million pieces at the end of the runway?

 

Best regards,

Robin.

Robin, to state that using an assumed temp or flex is 'bad news' is completey absurd, sure you are entitled to your opinion but don't expect anyone to agree with it.

 

 

 

The only problem onboard that aircraft in Sydney was with the flight crew..

Similar arguments for safety can be made in favor of using flex/derates as well.  Less wear/improved reliability during takeoff is certainly one.  Even putting those aside, I had been under the understanding that the 777 in some light load configurations is actually prohibited from using a full thrust takeoff (i.e. must use derate) because the asymmetric thrust from an engine failure would make the aircraft uncontrollable.  In fairness I haven't actually read the section of the flight manual stating this, but it does make sense with 110,000lbs of unopposed thrust on a long wing.

 

Eric Szczesniak

Robin, to state that using an assumed temp or flex is 'bad news' is completey absurd, sure you are entitled to your opinion but don't expect anyone to agree with it.

 

 

 

The only problem onboard that aircraft in Sydney was with the flight crew..

 

Of course, they even managed to input a weight that was considerably less than the empty weight plus the fuel they were carrying, alarm bells should've instantly been going off in their heads. Although the aspect of it that really confuses me is how on earth they were willing to accept the, what must've been, unusually low v-speeds. Given that they were Emirates pilots, and their A345s are, as far as I know, entirely used for long-haul routes the v-speeds given by the EFB would have been 30 knots less than the usual v-speeds for an A345 Emirates flight - yet this didn't seem to perplex them? 

Similar arguments for safety can be made in favor of using flex/derates as well.  Less wear/improved reliability during takeoff is certainly one.  Even putting those aside, I had been under the understanding that the 777 in some light load configurations is actually prohibited from using a full thrust takeoff (i.e. must use derate) because the asymmetric thrust from an engine failure would make the aircraft uncontrollable.  In fairness I haven't actually read the section of the flight manual stating this, but it does make sense with 110,000lbs of unopposed thrust on a long wing.

 

Eric Szczesniak

 

It has nothing to do with being uncomfortable - it is a safety issue.  As long as you have a big enough rudder and aileron effectiveness to control the aircraft with only 1 engine running, that is all that matters and demonstrating that is a part of the aircraft certification process.  Airplanes and aircraft certifications don't care about 'comfortable', just like the operating thrust on the engines doesn't care about how much the airplane weighs - it's going to give you the amount of thrust you command it regardless.  The performance you are able to achieve from that is all you are going to get for a given power setting.  On the opposite side of the spectrum, if the aircraft isn't able to maintain positive control in the event of an engine failure or at full power than engines must be derated (or bigger control surfaces put on the aircraft).  You see derated engines, from the factory, on a lot of smaller GA airplanes with big engines (typically Turbo-Prop engines). The Piper Meridian is an example - the turboprop engine is derated to 550 SHP because, if the engine were able to develop its full 850 SHP, the aircraft doesn't have big enough control surfaces to offset the enormous P-Factor that the engine creates at that 850 SHP; essentially sending the airplane tumbling uncontrollably.

Similar arguments for safety can be made in favor of using flex/derates as well.  Less wear/improved reliability during takeoff is certainly one.  Even putting those aside, I had been under the understanding that the 777 in some light load configurations is actually prohibited from using a full thrust takeoff (i.e. must use derate) because the asymmetric thrust from an engine failure would make the aircraft uncontrollable.  In fairness I haven't actually read the section of the flight manual stating this, but it does make sense with 110,000lbs of unopposed thrust on a long wing.

 

Eric Szczesniak

It's more to do with combining a derate with an assumed temp, you can cancel the assumed temp but not the derate if you lose an engine, it is due to calculated vspeeds and resulting Vmca

 

@ Luke, fatigue is pretty much the answer for such a huge screw up, the fact that both crew missed the mistake is truly amazing.

Of course, they even managed to input a weight that was considerably less than the empty weight plus the fuel they were carrying, alarm bells should've instantly been going off in their heads. Although the aspect of it that really confuses me is how on earth they were willing to accept the, what must've been, unusually low v-speeds. Given that they were Emirates pilots, and their A345s are, as far as I know, entirely used for long-haul routes the v-speeds given by the EFB would have been 30 knots less than the usual v-speeds for an A345 Emirates flight - yet this didn't seem to perplex them? 

 

American 965 out of Cali, Columbia is always the shining example of user input error.

If you don't want to derate a 777 with GE90-110/115B engines, prepare for a lot of back pressure. Of course, times when you actually need full power (wind shear conditions, runway length, TOW etc) then take it.

You're right that I'm not going to get everyone to agree with me (and I'm not going to try), but let me answer my own questions:

 

The root cause was incorrect entry, correct. BUT, what did that incorrect entry result in? It resulted in a LOWER POWER SETTING being used than was required (and this is the crux of the problem - why CREATE a problem by using less power than is available?).

 

What did the lower power setting result in? MORE RUNWAY LENGTH REQUIRED FOR TAKEOFF. They DELIBERATELY made the runway shorter as it was by using FLEX (pretty stupid IMHO), but because of the screwed up entry, IT WAS EFFECTIVELY REDUCED TO THE POINT THE AIRCRAFT HAD INSUFFICIENT RUNWAY.

 

Now to the cause of the tail strike: THEY PANICKED, APPLIED TOGA, and OVER-ROTATED in a desperate bid to get airborne before the (now inevitable) end of the runway.

 

See, if they had just used TOGA, they would not have had a problem, and we would not be discussing it now. Another A340 would still be serviceable, and 300+ passengers would not have been affected by the event.

 

In short, FLEX/ATM reduces options, and reduces safety (runway length is like altitude - better to have more of it in front than behind).

 

Best regards,

Robin.

Boeing has a free Performance calculator for the 777 available from the App Store on IOS.

Edit. Only available for the major international airports

You're right that I'm not going to get everyone to agree with me (and I'm not going to try), but let me answer my own questions:

 

The root cause was incorrect entry, correct. BUT, what did that incorrect entry result in? It resulted in a LOWER POWER SETTING being used than was required (and this is the crux of the problem - why CREATE a problem by using less power than is available?).

 

What did the lower power setting result in? MORE RUNWAY LENGTH REQUIRED FOR TAKEOFF. They DELIBERATELY made the runway shorter as it was by using FLEX (pretty stupid IMHO), but because of the screwed up entry, IT WAS EFFECTIVELY REDUCED TO THE POINT THE AIRCRAFT HAD INSUFFICIENT RUNWAY.

 

Now to the cause of the tail strike: THEY PANICKED, APPLIED TOGA, and OVER-ROTATED in a desperate bid to get airborne before the (now inevitable) end of the runway.

 

See, if they had just used TOGA, they would not have had a problem, and we would not be discussing it now. Another A340 would still be serviceable, and 300+ passengers would not have been affected by the event.

 

In short, FLEX/ATM reduces options, and reduces safety (runway length is like altitude - better to have more of it in front than behind).

 

Best regards,

Robin.

 

Of course, but how about we get into the umpteen other things that can go wrong if pilots set them up incorrectly? 

We can pray the once finished with PFPX they will make a TOPCAT 777 profile.

I can understand the argument for using all available power. However, from a long-term monetary standpoint derating the T/O is just a better option for airlines. Maintenance, etc....

 

And besides, (hundreds of?) thousands of flights occur each day with derated T/O's but they aren't all plowing ditches at the end of runways.

 

Almost ANYTHING can become dangerous if you screw up and do it incorrectly/carelessly. 

We can pray the once finished with PFPX they will make a TOPCAT 777 profile.

 

Fingers crossed.

You're right that I'm not going to get everyone to agree with me (and I'm not going to try), but let me answer my own questions:

 

The root cause was incorrect entry, correct. BUT, what did that incorrect entry result in? It resulted in a LOWER POWER SETTING being used than was required (and this is the crux of the problem - why CREATE a problem by using less power than is available?).

 

What did the lower power setting result in? MORE RUNWAY LENGTH REQUIRED FOR TAKEOFF. They DELIBERATELY made the runway shorter as it was by using FLEX (pretty stupid IMHO), but because of the screwed up entry, IT WAS EFFECTIVELY REDUCED TO THE POINT THE AIRCRAFT HAD INSUFFICIENT RUNWAY.

 

Now to the cause of the tail strike: THEY PANICKED, APPLIED TOGA, and OVER-ROTATED in a desperate bid to get airborne before the (now inevitable) end of the runway.

 

See, if they had just used TOGA, they would not have had a problem, and we would not be discussing it now. Another A340 would still be serviceable, and 300+ passengers would not have been affected by the event.

 

In short, FLEX/ATM reduces options, and reduces safety (runway length is like altitude - better to have more of it in front than behind).

 

Best regards,

Robin.

 

If you are that worried about things going wrong if an error occurs, than why do anything at all?  There are risks in everything you do, and if certain things are not done correctly, can lead to extreme danger.  This isn't specific to aviation, and if the risk were truly that large than we'd just ground every airplane in the sky and never fly airplanes again.  American 965 going into Cali, Columbia is a leading example - should we stop using FMCs, too?

 

You're going about the problem the wrong way.  It isn't about: "Well it happened, and if done incorrectly, it results in extreme danger; so lets just never do it again", but becomes a "This error occurred and presents extreme danger, but there are obvious (and large) benefits to doing so.  So let's create and design a system, procedures, policies, training, etc... to minimize or eliminate the risk as much as possible."

 

If the risk is truly too great, and the benefits don't outweigh the risks, than clearly the operation shouldn't continue.  It, of course, is also a function of avenues and procedures you can put in place to address the hazards (longer runways, detailed checklists, CVRs, training, testing, design, etc...) to reduce it.  These also have costs.

 

In the real world you encounter problems and find out how to reduce as low as reasonably possible and/or eliminate the risk; not simply say that the risk of exposure to this type of occurrence is less than 1% of all flights, and the consequences can be extreme, so lets just stop it altogether.  If we did the latter than we wouldn't be flying airplanes at all, driving cars, building things that can collapse, go outside, flying to space, etc.  There are extreme risks to everything you do in your daily life, and in which the risk has been reduced to extremely low because people took the approach to find the risks and reduce them to extremely low levels to where these things have become acceptable to us humans to do on a daily basis.  Subconsciously, you do a cost versus benefit analysis on everything you do on a daily basis.  If you go drive a car you are saying to yourself "The benefit of driving this car to X destination outweighs the risk."  In reality, you also full well know that the consequences of driving the car can be fatal. You realize the risk but you are willing to accept it.  Aviation is no different.

@3-2-1-Now

 

First off, WHAT'S UP WITH THE CAPS?

 

Secondly on a B777 that's lightly loaded not using de-rated thrust/assumed temp is probably a higher safety risk then using as the aircraft is way overpowered in that scenario. Therefore a lot more difficult to control.

Thanks gman !

I guess my thread has somehow been highjacked ;-)

 

Kevkev