Ed - can you name a major airport with a sufficiently long runway where your V1 theory would be practical.

John, it's not a theory, it's just physics. Someone mentioned earlier V1 = Vr. OK, say it that way. If you're light and have a long runway, you can get to Vr before you reach the point of no return (V1). When you reach Vr then you go.

Can we please just draw a line under this ridiculous notion that Flex/Assumed Temp thrust reduction is in some way unsafe.

Facts.

It reduces engine wear through lower EGT

It reduces the chances of VMCG problems

It allows far smoother climb out, imagine using full rated thrust in a very lightly loaded 757 with a 400oft level off SID, not fun for anyone

Oddly reduced thrust actually can help in an engine out situation, things happen slower and there is less chance of having control difficulties, plus you still have the protection by virtue of perf calcs that you will make all necessary performance criteria.

So can the idiot SLF who are prattling on about this please stop it.

If you put incorrect performance figures into the FMC and have incorrect speeds then yes, you are in a bit of trouble, but you could just as easily use full rated thrust and have some lunatic pop the speedbrake, retract flaps etc. That will kill you as well.......

As for the V1 > Vr argument, well words fail me. By definition it cannot be, fact.

Clown (how apt)
I think you are confusing "unsafe" and "increased risk". If you cannot see that there is an increased risk in using reduced thrust that delays rotation until near the end of the available runway for every take off, then I would ask YOU to kindly desist posting.
No one has answered this: Is the increase in risk associated with reducing the thrust for take-off balanced against the decrease in risk (as outlined in the Clown's post) AND the commercial benefit?

If it is, surely as PIC (and the acceptor of the risk), you are aware of the numbers involved, or your employer has told you not to worry, as THEY accept the risk on your behalf?

judge.oversteer

As I said, it was just an example to show that selected thrust may be as low as 60% of maximum thrust. I believe the fixed de-rates may be operator selected depending on the engine type. Even the sub-types may have a different "fixed" de-rate. (T/O 1, T/O 2)

Those percentages were for the RR with the Trent core, G and H cores may be different, as will GE and PW.

Climb de-rates (CLB 1, CLB 2) also washout at different rates.

I am sure an engine specialist can give you more information. :8

FrequentSLF (and others)

I am happy to use reduced thrust whenever it is available. Treat the engines with a little TLC and they will serve you well.:ok:

As many have said, the CORRECT reduced thrust does not reduce safety. :ugh:

We are assuming that some sort of Flex Thrust error caused EK's problem and that the repairs will be expensive individually for EK. You have to compare this with the global savings made by using Flex/De-rate on a daily basis.

[ Compare the useful life of an F1 engine (maybe 1000 miles/6 hours) with that of a well driven taxi (maybe 250,000miles/10,000 hours) and you may see my point of view. :rolleyes: ]

Ok then, let's compare. What, exactly, is the saving by using reduced thrust? Your F1 analogy is invalid, because the F1 engine performs at max for it's entire life. Max thrust used for take off would be in a burst of about 1 minute for an entire flight (of potentially 13 hours or so, as in the EK407 case).
Can you see what I am getting at? I'd just like someone to come out and declare that the risk numbers have been done, and that crews are aware of exactly what risk they are accepting. I'd expect that as airlines are big businesses with large sums of money at stake, someone, somewhere has done this.

ferris

Sorry you did not like my analogy.

Try this one:

Most engines are rated for 5 minutes (10 minutes in case of an engine failure) at max thrust. Try this for every takeoff and the engines will run out of useful life at a much faster rate than a similar engine treated with TLC. Thermal and physical stresses are so much greater at max thrust compared with max continuous or Flex/De-rate. That is why there is the time limit.

I think your 1 minute is a little mean for a 13 hour sector at close to max takeoff weight. I am just guessing (and from experience) that the average sector length probably is less than 7 hours for a 744/340 so twice the number of applications of high thrust per day/year.

Returning to the humble motor car for a moment. Do you ALWAYS use full throttle when moving off, or would you normally use sufficient power for a slightly more sedate departure? :}

Recommended reading:-

http://www.smartcockpit.com/data/pdf..._and_Climb.pdf

and more discussions

Why Derate? — Tech Ops Forum | !!!!!!!!!!!!!!

Well, with my Twin Otter, I would say anything longer than about 2,400 feet at gross weight and ISA would be long enough... :E

Full runway length
 

As the person who originally brought this subject up, I'd like to say that I was not implying it was poor airmanship not to use the full length of the runway. As has been shown above, there are sometimes valid reasons for not using the full length.

That said, not using the full length available is fine if everything goes OK, but it does seem that there are those very rare occasions when the runway behind you at the start of the take off run may have been just enough extra to get out of serious trouble.

Ex Cargo Clown

This idiot SLF has still something to say (nice to know that professionals have to resort to name calling when have nothing else to say)

as correctly said by No Land 3

Is exactly my logic. Now Ex Cargo Clown would you explain me why am I an idiot?

Thanks to all that have express their opinion about taking off at max trust.
The next logic question will be, why don't you set the trust that you want/need instead of flex/temp? Would not be easier to spot an error on the input of all the data?

Big Surprise !

That's exactly what is done........

Input the Flex/De-rate and /or Assumed Temperature,
N1 or EPR is calculated and displayed,
Thrust levers or Autothrottle moved to achieve that N1 or EPR

Even in the good old days of steam driven clockwork aeroplanes, (Super VC10 and B747-100/200 spring to mind) these calculations were done from the books, the N1/EPR was bugged and the trusty F/E set the appropriate thrust.

Not too difficult.....:}

Because you do not have direct access to the FADEC.

Access is via the FMC which "talks" to the FADEC.

There are many levels of redundancy for all these calculations,
ACARS RTOW calculations are rejected if rubbish is input.
Similarly, the FMC will reject many inappropriate inputs.

The old fashioned paper calculations mentioned above seemed to work without FADEC and other modern electronic gizmos.:8

When the various electronic calculators are unavailable, there is usually a paper backup method available with tables for weights/temperatures/pressures and wind components for the available runways.

[This was in reply to another question posted by SLF...which seems to have disappeared ! :hmm:]

SLF; what you propose would be reasonable if every take-off would be field limited; i.e. dependent on the length of pavement available. In practice, other limits apply as well, like obstacle and climb limits being independent limitations of the pavement length.
Since it is basically impossible to have all this data -up to date and everything; think of construction sites with cranes in a departure area- of every airport available in the aircraft, tables are mostly provided from an operations department which are guaranteed correct and up to date.

TOGA
 

SLF,

Next takeoff go for TOGA and leave them there:ugh:

Wonder how long the engines will last? Or how safe that might be?

AA

This will continue to go in circles as people, who obviously have no basic knowledge or understanding of the subject, continues to insist that something is wrong and should be changed. Arguing for the sake of it, it seems.

Flex Toga
 

Probably shown before but here is an Emirates A340-500 where a pilot selected TOGA 1/2 way during the take off roll. Interesting to see how close V1 and VR are. This flight was a light 3 hour flight.

YouTube - Take off from Sydney

So the anti-Flex/derate brigade's argument is, always full-rated unless an error has been introduced due to manual errors in calculating.

So by that rationale what about RVSM ? Maybe we should have min vertical separation of 2000 ft, maybe more, just in case someone mishears a clearance/put the altitude into the MCP incorrectly and it isn't cross-checked. Actually best make that 4000ft just to be safe.

What about departures at MAUW or MZFW. Surely they have to carry a greater level of "risk" as they are at the very edge of performance. Let's offload 2 tonnes of freight, actually make that 5 tonnes, just to be sure.

The fact are that there is no greater risk of Flex/Assumed Temp departures when done correctly. All figures are calculated that even the worst case scenario (engine failure at V1) is catered for as far as runway length goes, with the necessary safety margins.

If your argument is to use full-rated thrust to remove a possible error being introduced (incorrect V speeds or thrust set) then think about it this way, maybe gear shouldn't be retracted after takeoff, this will reduce the risk of the crew forgetting to lower it before landing.

How does that meerkat put it, oh yes, "Simples"

SLF comment
 

Dear All,

I feel that is time to stop the discussion on the pro and cons of reduced power setting on take-off.

Various professionnals explained in great details the setting actually used and the in-built safety margin.

Shouldn't we wait for the preliminary report instead of wasting bandwith?

Regards

Willy

This performance is all very simple really as long as you input the correct data. This nonsensical discussion of flex (used by EK)/derate (not used by EK) and TOGA shows that many here don't have any grasp of 'Performance A' and associated requirements.. And yes, a heavy 345 taking off with flex will often be rotating in the reds after a 4000m take-off roll, but as long as it clears the 'screen height' by 35' after an engine fails at V1 that's all that matters!!

As for the video on youtube a few posts back - if you listen they're just seeing 'how it goes' at TOGA when the aircraft is light.. Trust me, it's off like a scalded cat at light weight and TOGA...

I never advocated that, maybe if you read my posts you will notice that.

ek407
 

Hi to all,i have been silent to date about the incident,iwas on the flight along with my wife,down the back as usual very frightening and thanks to the people up front we got to ground safely,it doesnt matter so much to me who was and what was it happened,reading your posts i feel very lucky however no one has mentioned the after care once we had saftely disembarked.
It was appaling they burried their heads in the sand,we were allowed one three minute phone call one Emirates lady was on duty at check into hotel we got a free Hilton breakfast wow, then they put on a meal for lunch in one of the conference rooms ,they catered ,terrible,one lady still organising baggage and itinery,to say the least they were very very poor.
I have flown up the front with them excellent ,done it once BAH AUK return but it wouldnt have mattered where you were you still would only be allowed one 3 minute phone call .
So needless to say i will not fly with them again.
Interested to see anitial report any idea when its due.
Happy to be alive

Found this interesting, seems like a very similar incident to the one in Melbourne.

ASN Aircraft accident Airbus A340-313X A6-ERN Johannesburg International Airport (JNB)

West atc, http://www.pprune.org/rumours-news/1...nding-jnb.html

West atc - completely different scenario....

When i had previously mentioned Max take-off power for all take-offs , i didnt imply ALL available power, balls to the wall, EGT past the max etc. I meant a thrust level which is used to deliver rated engine performance while not exceeding any parameters AND delivering full engine life ! Dont let the bean counters tell you that 1-2 minutes at high thrust ( within limitations) on a good engine will sacrifice reliability and improve overall safety !!! Comprehensive engine inspections and care, proper care and feeding of the engine, High quality maintenance, NO previous overtemps etc and a GOOD engine to start with leads to longevity much more than minimal usage at near max temps etc.

west atc,
JNB and MEL have similarities but are actually very different.
In JNB there was low risk of tailstrike as the captain finally positively rotated 20 knots above Vr.

Please, can we have a forum for those who actually understand anything about aviation. I refer to the following, clearly written by a 12 year old.

This site was once a fantastic site, with insight from seasoned, and intelligent professionals.

Now it is infested with semi-literate idiots, who wouldn't know one end of an aircraft from another !

<Rant mode off>

Come on Rainboe, help me here !!!

Thanks for the reasoned replies. However, there seem to be a lot of people missing the point, not the least of whom is the Clown You really cannot see what is wrong with that statement? "Things are perfectly safe unless they go wrong". Abusing people because you cant actually put up facts as counter argument might show a certain party as being the idiot.

It is very easy to see the cost v. risk posed by offloading freight. It would also be easy to look at the number of events that could've been prevented by operating at less than MAUW (I'd venture to say none, without thinking too much about it, but you never know). The point is that there is a transparent, direct cost in offloading freight, but it appears that flex/derating and any benefits are purely theoretical.

If you are embarrassed because you do NOT ACTUALLY KNOW how much money (read engine wear/maintenance) is saved by using flex, that's fine. I didnt realise it was such a touchy subject. If your company knows, and just doesnt care to tell you and directs you to use flex etc. then the vicarious liability is theirs. In view of the treatment of the crew in this case, the company doesnt appear too keen on wearing that liability. I'm damn sure the insurer in the case of EK407 will be looking at it.

345 outta Sydney
 

Cool!!!... didn't know my take off had been put on You tube.... W

Ferris says:
Ferris is correct here, but

Smilin Ed says:
Smilin Ed is incorrect here.

If you follow company SOP's and use reduced power take-off's and/or intersection departures (or any other company SOP's for that matter), a tech crew is protected by the law of vicarious liability. If a tech crew ignores company SOP's and are involved in any incident that results in any liability, a crew may be found negligent and a court may then find them liable. This is not to say a crew must used reduced power or intersection departures, that decision is always left to the PIC.

+G

From ‘The Naked Pilot’ by David Beaty
Firstly, there should be an acknowledgment that if and when the pilot makes a mistake, his will probably be the final enabling one at the apex of a whole pyramid of errors down below. This will, in turn, take the heat off investigations – the ‘we intend to find and punish the culprit’ syndrome. Only then can the pilots come forward and admit to mistakes they made or nearly made, and the reasons why can be coolly analysed and lessons learned. [Page 285]

Professor Reason in Human Error (1990) distinguishes between active error, the effects of which are felt almost immediately, and latent error, the adverse consequences of which may lie dormant within the system for a long time. This can clearly be seen in aviation, where pilots at the sharp end make an active error, while latent error lies behind the lines within the management support system. Many of these are already there awaiting a trigger, usually supplied by the pilot. ‘There is a growing awareness within the human reliability community that attempts to discover and neutralise those latent failures will have a greater beneficial effect upon system safety than will localised efforts to minimise active errors.’

As long ago as 1980, Stanley Roscoe wrote that:

The tenacious retention of ‘pilot error’ as an accident ‘cause factor’ by governmental agencies, equipment manufacturers and airline management, and even by pilot unions indirectly, is a subtle manifestation of the apparently natural human inclination to narrow the responsibility for tragic events that receive wide public attention. If the responsibility can be isolated to the momentary defection of a single individual, the captain in command, then other members of the aviation community remain untarnished. The unions briefly acknowledge the inescapable conclusion that pilots can make errors and thereby gain a few bargaining points with management for the future.

Everyone else, including other crewmembers, remains clean. The airline accepts the inevitable financial liability for losses but escapes blame for inadequate training programs or procedural indoctrination. Equipment manufacturers avoid product liability for faulty design,. Regulatory agencies are not criticised for approving an unsafe operation, failing to invoke obviously needed precautionary restrictions, or, worse yet, contributing directly by injudicious control or unsafe clearance authorisations. Only the pilot who made the ‘error’ and his family suffer, and their suffering may be assuaged by a liberal pension in exchange for his quiet early retirement – in the event that he was fortunate enough to survive the accident

Yet it is only recently that very dubious management malpractices are being identified and their contribution to accidents given sufficient weight. For though the pilot’s actions are at the tip of the iceberg of responsibility, many other people have had a hand in it – faceless people in aircraft design and manufacture, in computer technology and software, in maintenance, in flying control, in accounts departments and in the corridors of power. But the pilot is available and identifiable. [Page 221/222]

An incident/accident is generally the result of active failures (pull the trigger) on the part of the cockpit crew, but the stage may have been set by the latent failures (load the gun and put the safety catch to ‘fire’) introduced by others (management practices, certification standards, aircraft design, software, ergonomics etc etc). Put another way, the cockpit crew is the last line of defence for every ones mistakes. As good as you may think yourself, none of us are all knowing.

Capt. Fenwick of ALPA has cautioned. "Pilots will be judged against the perfect pilot flying the perfect airplane on the perfect flight. We all know that no such thing exists.”

What would EK's response be to the above?

I have not seen any post here about the matter I wish to raise, hence I will risk a post.

People on this thread talk about one of the reasons for reduced thrust takeoffs as "reduced engine wear".

I respectfully advice that it's not "reduced wear" as in the wear of the bearings in a car engine, it's actually reduced engine life which is somewhat different. Turbine blades and guide vanes are generally operating at maximum takeoff power in gas streams some Two to Three hundred degrees above the melting point of the alloys from which they are made. What keeps them from melting is the flow of cooling air through their bodies.

Despite the internal cooling, the gas stream gradually erodes the blades and vanes, and the rate of erosion is a direct function of temperature and time. The hotter they are, the longer they are, the shorter their life before they degrade to the point where they must be exchanged. I can't find images on the net of what they look like before they are replaced, but I can say they look something like a sort of melted turbine blade shaped icecream.

The motive for reducing takeoff thrust is thus to maximise the life of the blades and vanes which are effectively consumables, even though every airline I'm aware of keeps those that cannot be repaired in the (vain) hope that one day new repair schemes will one day allow these super expensive items to be returned to service.

To put it another way, the time X temperature product of the blades is finite, and each take off consumes a little of that finite life. That's why it is desirable to use the minimum thrust consistent with safety.

Flex is not really the issue here.

It is recognising and catching invalid numbers for a particular aircraft weight and takeoff condition (thrust and performance) when distracted, tired, rushed and/or constrained to complex SOPs and patter.

It is how to catch these numbers before using them kills you and your passengers.

On Flex - a technique that I was taught and like was to 'Flex' only to no less than 2000' of the available runway length, intersection or full - an extra safety margin adopted by many operators of my type.

A takeoff in conditions that required any greater amount of the runway than that required full takeoff thrust.

On top of normal V speeds, knowing that you should be at 35' by 2000' to run and seeing that point approaching quickly is a recognisable point at which to apply TOGA if less was leaving you under-performing.

It would seem reasonable to me to only flex in a heavy to within 4000' of runway available.

And the fate of the airplane?

Pilots seem to have been dealt with and put out to pasture, but expect that some one will see the total story, and maybe they will be back on the job, perhaps with a more understanding view by new management.

But the airplane, is it to be fixed, surely with all the skills here and with the help of Airbus it should be put back in the air.

Regards

Col

No worries, happy to be corrected. :ok:

Sunfish, thanks a lot for the insightful reply.

Yes, the effects of high turbine inlet temperature are very real, measurable and computable, not only increasing cost, but also statistically reducing reliability. Big carriers dealing with tens of thousands of flights every year have to take that into account.

Here's an interesting article about turbine blade coating, that contains some photos that dramatically show the erosion (and also, how advanced coatings reduce that erosion).

In some of the blades you can see little holes, which are the outlets for the cooling air mentioned. It is pumped into the blades from the root, and blown over their surface to keep them from melting.


Bernd

http://www.pprune.org/2302593-post81.html
.
Excuse the drift, but this pic shows more detail of those little bits at the back of the Engines, these are in poor condition however !!!

megan;
Well, clearly we have the answer to that question. The crew is apparently history and it doesn't appear as though a report will be issued as to what happened. Even though there are some reasonable scenarios posited, not discussing what happened, even informally, means that the error, whatever it was, has opportunity to re-occur. It has occurred before and the opportunity to learn from what happened here has, it seems, been lost in favour of firing the crew.

It seems that this is the sum total of EK's desired contribution to flight safety, particularly in reference to the knowledge base of this kind of incident.

First posting. Many years lurking
 

Megan,I must say I agree with you 100%. Very well said. I am sure that the "blame culture" of the middle east has alot to do with the way this crew has been treated. It saddens me to think that I came from a place where these people would have retained there jobs and management would have looked at ways to close these gaps in the operational safety. Not here. As this puts the blame on management which puts there jobs in jeopardy.. Sh1t flows downhill and management won't admit there shortcomings because of it. My condolenses to the crew for being the sacrificial lamb. Now we will place another bum in the seat who in this environment could do the same mistake. Truly Sad