AF 777 wrong weight inputs, off by 100 tonnes?

[voyageur9]

Exclusive: Air France faces new safety probe after freighter takeoff scare | Reuters (http://www.reuters.com/article/2015/05/29/us-airfrance-probe-idUSKBN0OE1N020150529)

[exeng]

The old type the ZFW into the TOW boxes trick I would imagine. That was also done by a BA crew in the early days of 777 ops.

[B-HKD]

Boeing customer option on the 777 is to remove Gross weight entry from LSK1. Not sure if AF purchased this option on the 77F fleet (2 aircraft).

MTOW on their 77Fs is 347,000kgs (Highest option on the -200LRF).

Operating CDG-MEX fuel would be 90-95T. With a payload of 80-100T TOW would be 320t up to MTOW. If indeed they were off by 100t they either entered the wrong TOW or ZFW in the TOW field (if that is enabled on their aircraft). EK almost lost a A345 at YMML a while back due to the same mistake. Gross Weight being entered 100t lower and the crosscheck wasnt done correctly.

Since then, they have purchased the the Gross Weight try field REMOVED option on the 777 fleet and I assume the Airbus too if that is an option. And also disabled it on previously delivered B777s. This being one step along with additional training and emphasizing of doing the weight & balance calculations separately and crosschecking.

At least the AF crew realized acceleration was insufficient and aborted before going off the end...However you do wonder if they were experienced on type why they would let themselves get away with a far too big de-rate/assumed temp. If you are running the takeoff performance numbers for a 11h+ sector, and the assumed temp comes back as TO-65C that should raise a red flag....

[BARKINGMAD]

Avoid? Not in this case, though done every day by all FMS loading crews.

Trap? Not in this case, could be by structured ritual during loading.

Mitigate? Well done guys, you didn't scrape metal nor kill/physically injure anyone!

IIRC, Singapore Airways did the same by 100 tons a few years ago, (fuel?), in a 744 and scraped the tail so much that the ground engineers were surprised the APU stayed in place.

Lots of stuff re this topic in the Boeing Magazine since, but still someone somewhere tries it again.

A formal ritual involving both/all pilots present on the flight deck, sterile flight deck with no distractions from CC or ground staff, would help to stop this one dead. So would the practise of calculating, by brain, a gross error Vspeed, viz V2, from the CFP and annotating the CFP with it at the briefing stage, then comparing when finally loaded in the flight deck.

The 73NG used to come out with a very close last 2 digits of V2 @ flap 5 by subtracting 25 from the TOW within a knot or two. Of course these days there are too many variations on thrust reduction like derates plus TASS for takeoffs so this may not be valid any longer. But it certainly kept me and others out of the trees at screen height when I was operating.

There, that's my pennyworth of problem-solving. I look forwards now to the inevitable flood of widgets, gadgets and software mods proposed by all the wannabe aircraft engineers/pilots out there, knowing that even if such hardware/mods get approved for use, it will be years before they are incorporated in ALL 'frames.

Meantime we will read more stories of gut-wrenching moments as the next crew to do this realise they are going nowhere fast and may not miss the hard stickey uppy bits at the end of or beyond the stopway and a careers/lives are about to end. :ugh:

[seafire6b]

Another previous such instance as below, very hairy! :


Emirates Flight 407 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Emirates_Flight_407)


Actually got airborne, doing some major damage on the way, then returning after dumping fuel.

[perantau]

http://www.taic.org.nz/ReportsandSafetyRecs/AviationReports/tabid/78/ctl/Detail/mid/482/InvNumber/2003-003/language/en-US/Default.aspx?SkinSrc=%5BG%5Dskins%2FtaicAviation%2Fskin_avia tion

[DaveReidUK]

At least the AF crew realized acceleration was insufficient and aborted before going off the end

Did they? The Reuters article implies that they got airborne:

"To compensate, pilots had to override the automated settings and order up maximum power from the aircraft's two engines.

Air France confirmed the incident in response to a query from Reuters and said the crew had been taken off flying duties once they had reached their initial destination."

[phiggsbroadband]

To quote... Emirates Flight 407 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Emirates_Flight_407)


Airbus are going to find a Software update....


That will be nice.... We can all sleep safe in our beds.

[speedrestriction]

I normally scribble down estimated Green Dot speed when we decide on the fuel load then compare it to what the FMGC spits out. Usually within 2 knots - pretty bulletproof cross check.

[TheiC]

To save others the trouble... Discussion: Why don't aircraft weight themselves?

http://www.pprune.org/tech-log/315101-why-dont-aircraft-weigh-themselves.html

[GlobalNav]

@IC quote "To save others the trouble... Discussion: Why don't aircraft weight themselves?"

...and fly themselves? That's coming too.

Mistakes happen, it's the crews who catch them before the bad consequences that keep us safe. If the airplane had its own scales in the gear, that might be a truly good cross-check, but if it becomes the primary means of establishing the GWT, the crew's mental cross-check is likely to vanish.

Failures occur in any electro-mechanical system, and I doubt the automatic system would have the integrity/redundancy to be the primary means. But it would no doubt be used that way.

[sandiego89]

And I love that Reuters used the wrong aircraft stock photo in post #1....Hey twin engine jet- close enough....

[JammedStab]

747F can weigh itself....when it works.

[Lookleft]

The SQ 744 actually had the APU catch on fire. They rushed the first circuit and had to go around. The issue with that one is that the Capt. had come off the A340 so he was not surprised to see a V1 around the 12ish mark. The TOW was 397T so one of the 3 crew should have queried the box numbers. As someone said though gross error checks are not taught so much these days.

[Fris B. Fairing]

The thread referenced in post #10 mentions STAN (Sum Total And Nosewheel)

http://www.adastron.com/aviation/vault/stan.jpg

I acquired this paperweight as a reminder of technology that didn't put me out of a job.

[EW73]

The electronic weighing system on the B747-200 freighters we flew in AHK some years ago I recall were fairly accurate(ish) and reliable(ish), . . .but hey...we had flight Engineers and subsequently never had a problem with takeoff performance over a very wide variety of departures. :)

[Bigpants]

A poster above uses best guess green dot. My version is to best guess a V1 and Flex Temp. Bit of fun and makes the brief interactive as we discuss any differences between best guess and EFB.

[Willie Nelson]

Big pants suggests that best guess at V1 and flex temp might be good.

Problem with that idea is that there's so many variables on V1 other than weight, such as wet versus dry. I'd suggest VR/V2 for a given weight and flap setting would be a better indication to compare to your flex.

We've recently switched to Airbus fly smart iPad software, it's a great bit of kit but I've certainly started doing a lot more gross error checking of speeds flap setting and weights prior to departure.

Our outfit recently had a flap 2 takeoff on a runway which should have been set to flap 1, luckily this was a 'conservative failure', had it been the other way around there would have been much gnashing of teeth. As a result of this we found out that the flap indication in the MCDU provides noTO CONFIG warning in the event that it does not match the selected flap. My point being, it's not only the weight being correct that is critical.

[Heathrow Harry]

you'd think with all the technology around it would be pretty easy to have a (small) gadget that gave the aircraft weight to say +/- 1 percent................

[Monarch Man]

777 perf GW error check works on 200LR, 300ER etc

TOW/3+65=vref within 1-2 kts, if it's any larger than this you've made a boo boo.

[AdamFrisch]

Here's a thought - just use full power on all takeoffs and problem goes away.

[jurassicjockey]

Not if you rotate 20 early

[Piltdown Man]

This 100 tonne error is regularly made by aircrew in all sorts of airlines. Mortals only get to hear about the incidents where there is some noise attached. What is clear is that no airline or manufacturer appears to have bullet proof method of prevention. A manually (yes, in this day and age) calculated speed (V2 or Vfs etc.) guess based on estimated load, DOW and fuel compared with the figures generated by the loadsheet might be the way forward. More silicon is probably not a good idea because it may use the use the same rubbish as input.

[ShotOne]

Sadly, because of the design of electronic performance programmes, these are going to keep on happening. It's easy enough to scoff at how silly someone must have been to make a 100 tonne error, but that's not how these accountancy based systems work. We're talking about a single misplaced digit. With old style tables a gross error was far less likely.

[CaptainProp]

That would be to admit error. Not happening. Not in AF.

[Prober]

Re post No 15. Yes indeed, Stan has existed for many years but is not completely infallible. We had it on the old Vanguard freighter, the Merchantman (VC9). It had not been certified for the aircraft (IIRC), so had no limits attached but it did give a rough idea. I very nearly came unstuck but was saved by STAN. I have ALWAYS, from my days as a Second Officer to Senior Captain, done a rough gross error check. I believe its called "professionalism". In the case in point, the total weights were approx correct but, being the middle of the night in the middle of winter and considering that some cretin had kicked the plug out of the weighing machine's heater, it recorded all pallets as having the same weight. Coincidentally, the total was almost correct. However, the individual weights were at great variance and when, on doing the STAN reading whilst taxying out and the C of G reading was way out, as we came to a stop I could feel the aircraft trying to settle down on to its tail.
Thank you, STAN!:D

[Metro man]

Sounds like it came close to another Mk Airlines at Halifax. Wrong weights resulting in wrong power settings and t/o speeds.

[Station_Calling]

Here's a thought - just use full power on all takeoffs and problem goes away.

And reduce your on-wing engine life by how much?

[JammedStab]

Of course the smaller the plane, the greater the amount of percentage error is a 100 ton mistake.

So what do you do to prevent this. We put the planned ZFW in the ZFW column of the FMC upon initial entry. Then when actual is read out, I point at the ZFW in the FMC and then enter it. A large difference should be questioned.

The OPT initial calculation is from the planned GTOW number on the flight plan(the ZFW number is not used). A significant difference here upon final calculation should also be questioned.

I also look at the V2 speed and see if it makes sense for general weight.

Any other suggestions are welcome. Obviously it can happen.

[Volume]

And reduce your on-wing engine life by how much?
Of course this is an on-wing engine life vs. on-board pax and crew life issue... At least it could be one day.

[RAT 5]

JammedStab's method should work: i.e. a comparison between planned/expected data and actual data. Further, I think there needs to be a whole attitude change. Many of us were brought up in the era of 'gross error checks'. There were little tricks we all used to have a 'ball-park figure' in our heads. This covered many items. Today's education, in so many fields, is to use japanese brains and believe what they tell you; no gross error check in your own brain. This has been contributed to by the lack of mental arithmetic in schools I often get cadets on the TQ course who struggle with basic speed/distance/time calculations. Ground speed/ROD/VS calculations. It's all VNAV and FMC to find the answers. Guys who use calculators to add up load sheets etc. Often it's slower anyway, but they have not been schooled in this way and given the tools.

[burgerbun]

I liked when, based on our estimated TOW, we would preselect V2 in the MCP, then once the data was in, comparing the speeds was an easy way to see if we had made a mistake somewhere. But somehow we don't do this anymore :rolleyes:

[Flying Clog]

Anyone with half a brain does, why don't you? You need the company to tell you to do it?

:ugh:

[phiggsbroadband]

Perhaps, during the walk-around, if you noticed a fully extended Nose-Wheel Gear,
that would start alarm bells ringing...


Or that the stairs don't quite reach the door...

[JammedStab]

I think that might be more of a loading position problem than a V-speed problem.

Plus, some jet freighters have a tailstand pushing up on the tail of the aircraft for loading during the walkaround. The other day, there was no nosegear oleo showing, so it was checked after the tailstand was later removed.

[latetonite]

I am confident that I would have caught this 'slip'. If not in the crosscheck and V2 input, then during acceleration in the take off roll.

[fab777]

The crew actaully caught the slip: TOGA set, limit the pitch angle in order to protect the tail, retract the flaps and slats way over the computed speeds. Pretty good mitigation of the initial error, no harm done.

6 years of hard work changing everything in the airline operations and the company safety culture, and here we are wondering why we're facing two near disasters in a couple of week.

BTW, answer to post 26: a LOSA audit is being done as we speak, the second one in 3 years. And for the halfwits tinking like post 27, the B777/744 fleet manager offerded his resignation yesterday.

This is being taken seriously.

[Bokkenrijder]

6 years of hard work changing everything in the airline operations and the company safety culture, and here we are wondering why we're facing two near disasters in a couple of week.I don't want to throw stones in this glass house that all of us pilots live in. Mistakes happen, and then most important point is that we all learn from it. Yet I can't help but notice that the number of incidents and accidents of AF is becoming a bit scary.

Could it perhaps be that the problems with AF's safety culture are a lot older than 6 years? Air France accidents and incidents - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Air_France_accidents_and_incidents)

Could it also be that perhaps the real problem is not really the safety culture, but rather an extremely arrogant superiority complex culture, also known as French chauvinism? An inbred culture that is not open for change? A culture that prevents fresh (foreign!? English?!) ideas and lessons to take root? A culture that insists of doing everything "the French way" by actively swimming against the stream of common sense, from speaking French to ATC, to having checklists and call outs in French and making an LP6 in French more important than an LP6 in English?

Could that perhaps be the real problem here? A problem that has been discussed here on PPRuNe for many many years, and a problem that any non-French pilot can easily identify after just a few flights to France?

[fab777]

I'm not going into details, but you are totally out of line. You obviously have no clue about what's going on here and the way we work.

Considering the number of incidents, ATC watcher wrote an excellent post about that. Do you really think that nothing happens in, say, the ME3, or some famous european LCC? Of course, they never show up on avherald, but try to guess why.

As for arrogance, I will let the reader guess who is being arrogant here, and who is feeling superior.

[ZBMAN]

Could it also be that perhaps the real problem is not really the safety culture, but rather an extremely arrogant superiority complex culture, also known as French chauvinism? An inbred culture that is not open for change?

Now that is the most arrogant piece of crap I have read in a long long time. :mad:

And FYI I believe procedures are now done in English in AF, at least on the airbus fleet. Maybe an AF pilot could confirm, but I doubt any would be reading this topic - probably gave up reading and disgusted by all the drivel on here about the french this and the french that... Listen to yourselves for christ sake :=

I am not saying that the french are perfect, but all cultures have their own peculiarities. I could easily have a go at the Dutch or the spanish or Italians, and certainly the brits, but I won't. They all have bad sides, but that doesn't make them, as a whole, bad pilots, as some here seem to suggest about the french.

Serious incidents occur in most airlines, especially in large ones such as AF, and even in some airlines that portray themselves as the best in terms of safety. The fact that those incidents don't make it into the open doesn't mean they don't occur, only that they are kept under wraps. How's that supposed to improve safety?

[Bokkenrijder]

Do you really think that nothing happens in, say, the ME3, or some famous european LCC? Of course, they never show up on avherald, but try to guess why.Okay let me guess: because, it's all one big conspiracy against AF/the French? :rolleyes:

[Bokkenrijder]

I am not saying that the french are perfect, but all cultures have their own peculiarities. I could easily have a go at the Dutch or the spanish or Italians, and certainly the brits, but I won't.Absolutely right, however there are also plenty of other cultures and nationalities working for BA, EZ, KL. They all have bad sides, but that doesn't make them, as a whole, bad pilots, as some here seem to suggest about the frenchSo why aren't there that many topics about British, Dutch, Italian or Spanish airlines then?

Is it all one big conspiracy ay, and LH, IB, BA, EZ, FR and KL all have percentage wise the same amount and severity of incidents and accidents then? :hmm:

[silvertate]

Here's a thought - just use full power on all takeoffs and problem goes away.


Brilliant idea.

So you take off fully laden on a 2,000m runway at 3,000ft elevation, at 35oc with a 5 kt tail. But you use full power and everything will be..... everything will be..... Ahhhhhhh.....

You are not a pilot, I hope. :ugh:

[silvertate]

I'm not going into details, but you are totally out of line. You obviously have no clue about what's going on here and the way we (the French) work.


Actually we do have an idea. We all know that French ATC have the worst grasp of English in the world, because they refuse to practice it with domestics.

We all know that French ATC put on an unecessary accent, when every other nation can speak English without deliberate inflections (apart from Greece, perhaps).

We all know that airports like CDG have the worst signposting ('cos the locals know where they are going, so everyone should).

And having worked for a short while for Air France I do know how a leper feels. Some of the passengers thought it appropriate to swear at us, and our stupid 'roast-beef' aircraft. I did purchase a bell at one point, but the humour was completely lost in translation.

And we only have to extend those external perceptions to the internal scructure and training in AF, to imagine the many problems. But whatever the problem is, it is axiomatic that there IS a problem, so protesting innocence is simply not good enough.

[EEngr]

This 100 tonne error is regularly made by aircrew in all sorts of airlines.Please don't say that. As occasional SLF, I'd like to think that there is some sort of CQI process at work to catch the outlying events and work to eliminate sources of error in the process. Don't get me wrong: I appreciate the piloting skill that manages to get my overweight flight off the runway. I just hope that someone is working to reduce the incidence below what one would define as "regularly". :eek:

[ZBMAN]

Absolutely right, however there are also plenty of other cultures and nationalities working for BA, EZ, KL

And your point being?:confused: You might be surprised to know that several nationalities work in AF as well.

So why aren't there that many topics about British, Dutch, Italian or Spanish airlines then?


Perhaps simply because it seems widely popular judging by the comments on this topic, to slag off the french.

AF have had more than their fair share of problems. Tremendous work is being done internally to solve those problems. However incidents will still occur, as in any other airline. The two recent events, however serious they may be, have occurred in other well respected legacy or low cost carriers. In particular, I'll let you guess which airline has an appalling record of unstable approaches, overruns, near fuel exhaustion due to ludicrous company fuel policy, severe GPWS events, and a hull loss. Not to mention intentionally flying with missing bits of aircraft. That they have not killed anyone yet is purely due to luck... Yet they enjoy a rather undeserved reputation in terms of safety. so as someone said (oh it was you! blimey!) let's not throw stones in the greenhouse, thanks.

You hate the french. Fine. But don't let it cloud your superior judgment...:rolleyes:

[ZBMAN]

Actually we do have an idea. We all know that French ATC have the worst grasp of English in the world, because they refuse to practice it with domestics

I agree that they are not the best - but they are far from being the worst! Have you actually been anywhere other than brussels? Have you been to Spain lately? Or anywhere around the mediterranean? Or in Asia?

Oh but wait no one is being excessively negative about the french to the point of literally making things up... This is only a conspiracy theory. :roll eyes:

I'll leave you to it then. If it makes you feel better about yourselves please indulge :ok:

[Bidule]

@silvertate when every other nation can speak English without deliberate inflections (apart from Greece, perhaps).

And maybe apart from Texans!


This being said, maybe AF are on news because the French Safety Office (BEA) issues bimonthly lists of incidents on their public website. Not many safety offices do the same.... Not seen, not caught!

[pax2908]

Searching through the U.S. ASRS database, it should be possible to get an idea of what is happening elsewhere. Those reports are anonymous, of course. For instance report number 1202628 says "B757-300 FO reports being given the zero fuel weight by the Captain when requesting the takeoff weight for V speed calculation. The aircraft does not rotate or lift off at the predicted speeds, but does takeoff and climb normally once the required speed is obtained."

[VR-HFX]

I would humbly suggest that this is just another example of cockpit dumb down.

Anyone who has "actually" flown real a/c and not just on FS has some common sense checks based on expected V1, VR and V2 numbers for the a/c type and approx guessed TOW. These numbers sit in your brain as defaults. When you see a number that is 20-30kts different it should trigger an immediate "excuse me, let's stop and re-think" moment.

If it doesn't the crew is either incompetent or so fatigued that death is an acceptable option.

[Squawk7777]

AF has had more than their fair share of incidents/accidents in recent times. If I were their CEO I would have an outside company undergo a thorough audit on their training and proficiency standards. Something is not right.

Show me one airline that does not have incidents on a regular basis. It's called "flying the line" or "sh!t happens". I agree the attitude and/or culture can and does play a role however even operators with a better safety record deal with incidents and their tendencies every week. It's a constant improvement process. My airline publishes safety bulletins on a regular basis, if I'd publish every incident on here, you won't be able to sleep! I bet you the same with your operator or your favorite airline.

Could it also be that perhaps the real problem is not really the safety culture, but rather an extremely arrogant superiority complex culture, also known as French chauvinism? An inbred culture that is not open for change? A culture that prevents fresh (foreign!? English?!) ideas and lessons to take root? A culture that insists of doing everything "the French way" by actively swimming against the stream of common sense, from speaking French to ATC, to having checklists and call outs in French and making an LP6 in French more important than an LP6 in English?

French vs. English. Another PpruNe pet argument. Open your horizon and look at some Canadian operators. Or look further South where people speak Spanish (Shock, Horror!). According to your theory planes should be flying out of the skies daily! I disagree that speaking English to ATC in France/or elsewhere will improve anything. Other countries do it their way also (using their native language), and many people live with it just fine! I have discussed this issue many times here, and I firmly believe that this argument is a PpruNe Francophobic pet argument (did you know that even Germany allows German/English ATC radio comm?). Why is the language issue mainly brought up with France on this bulletin board? There is more airspace on this planet where Spanish is used. But there's hardly any complaint! Why is it that mainly the Brits complain about France and their ways? Contempt, historical roots, war of cultures? I have yet to see the same amount of discussions on this issue on a US bulletin board. And there is Spanish-speaking airspace "down South" that's much more challenging! Besides, on a busy frequency (ORD, JFK, CDG, FRA sometimes) it is nearly impossible to maintain aural situation awareness just by listening. The TCAS screen/overlay has mainly solved that problem.

So why aren't there that many topics about British, Dutch, Italian or Spanish airlines then?

This being said, maybe AF are on news because the French Safety Office (BEA) issues bimonthly lists of incidents on their public website. Not many safety offices do the same.... Not seen, not caught!

Thank you! I was looking for this reporting reference. I wonder how many other authorities are doing "this" to their national/favorite carriers? Remember the LH crosswind/wingtip incident in HAM? This incident was brought to the public's attention not through a safety report but YouTube. And that video was taken off line several times, in order to prevent bad publicity.

This whole safety statistic argument is mainly fruitless because there are no standards in what gets reported, what operator was involved, and what gets published (to the average plebs, anyway).

I was unfortunate enough to fly a now defunct Mexican carrier called Aerolineas Internacionales. PERFECT record! No accidents or incidents. On paper!

In German there is a good saying "Papier ist geduldig"

[chillpill]

Finally... a commonsense comment (made by VR-HFX) ...

'I would humbly suggest that this is just another example of cockpit dumb down.

Anyone who has "actually" flown real a/c and not just on FS has some common sense checks based on expected V1, VR and V2 numbers for the a/c type and approx guessed TOW. These numbers sit in your brain as defaults. When you see a number that is 20-30kts different it should trigger an immediate "excuse me, let's stop and re-think" moment".

I would just add to this that include an appreciation of an approximate thrust setting... and then incidents like this should NEVER happen.

But... commonsense ('airmanship')... Either you have it or you don't... :roll eyes:

THAT is the problem in todays aviation IMHO... And that goes a lot further into the entire selection and training debate... which in todays world seems to have been dumbed down by the size of the 'sponsors' wallet... :rolleyes:

[Flying Clog]

Bingo!........

[VNAV PATH]

Quoting ATSB report about Emirates weight/speeds errors on Melbourne take off (100 t error):

Incorrect weight 262.9 t : V1=143 VR=145 V2 = 154 FLEX temp = 74°
Actual weight 362.9 t : V1=149 VR = 161 V2=173 FLEX temp = 43°

In previous 2 months, pilots used 3 A340 types, weight ranging from 150 to 370 t and quoting one pilot, numbers are loosing their meaning, they become only numbers...

Still bingo ?

[RAT 5]

I fly small a/c B738 in comparison to these guys. I did fly B767's -200 & -300, but the weight range was not too drastic. As suggested I have a 'feeling' for the correct figures. Reading this thread I now appreciate the spectrum of weights the A340 & B777 -ABC, -FGH, - XYZ can throw at you. Thus it is not quite so easy as I would have expected. Having a 'feeling' for the numbers might not be quite so instinctive as many of us might have thought. Still.......

[ShotOne]

VR HFX's comments may have been commonsense but don't reflect how things are now. I am likely to be flying an aircraft at 70T one day and another at 230T the next. The performance programmes are clunky to put it politely and a single digit out of place can cause a major error which isn't necessarily obvious.

[Old Fella]

Reading the majority of posts on this thread leads me to a number of conclusions. The most over-riding one however is that many posters seem to blame the technology or, in some cases, the fact that they fly aircraft with large performance/weight differences on a given day. As a former F/E with responsibility for initial extraction of performance data from tabulated data which was then confirmed (with out access to the TOLD card) by the non-handling pilot I never knew of the gross errors which seem to occur from time to time in more recent times. I know I come from another era, however I believe that now that there are only two sets of eyes in the flight deck of heavies that the insertion of data into the electronic systems should demand double checking. It is, or should be, a self preservation action if nothing else.

Just wanted to remark on EEngr's post in relation to Piltdown's earlier post. I certainly do not believe the 100 tonne error is made regularly. I am aware of several which made the news and I accept that an occasional event occurs which goes unreported. I also am aware that the work load is now higher than in the past with all sorts of varying power settings being used. It was pretty simple in my day I guess with only two or three derates available and fairly basic data from the steam age being used.

[KenV]

you'd think with all the technology around it would be pretty easy to have a (small) gadget that gave the aircraft weight to say +/- 1 percent................

A system with that level of precision is really easy to design and build.

A system with that level of accuracy under all loading conditions over several years of service? Not so much.

[ShotOne]

Old Fella, in the good old days when we used tables as you describe, an error might swing things by a knot or two. That's not how it is now. There's still a cross-check as there always has been but the calculations are very error-intolerant and have to be done multiple times for various runway options and often revised at the last minute under time pressure when the load changes

[Interested Passenger]

How much deflection is there in the undercarriage between empty and dry to fully tanked and loaded? Could the difference in height be measured and used as a double check, turning a 777 into a giant set of scales?

[Fursty Ferret]

Nice idea, but oleo extension varies with temperature / pressure / crosswinds / etc etc etc

[deptrai]

Sensors capable of measuring pressure on each landing gear to calculate weight exist, have been installed and tested. Ground based systems have been tested as well. Would be nice to have as an extra layer of safety; that we don't see a lot of them is about cost I guess. Cf post #10

[WingNut60]

Earthmoving trucks have had loadweigh systems for quite a while.
Pressure transducers in the struts and a control (summing) module - not such a great expense.

Not sure that accuracy would be suitable for more than a cross-check, but the hard part for the trucks is the slope and condition of the ground that they're sitting on.
That may not be a problem for aircraft on the apron. Or I hope not.

[framer]

In my airline the calculations are made completely independently by the F/O and the Captain, on seperate Performace tools, with no discussion. Each individual sources the zero fuel weight figure independently, adds the fuel amount, adds a buffer for last minute changes and then at a time that suits the crew say " what did you get?" And a comparison is made. Once in a while the figures are a bit different because someone has not accounted for a wet runway or something similar and further probing ensues in order to determine who is correct. The system works well and the greatest weakness in it lies in the load control office where the zero fuel weight is calculated.
The second greatest weakness is in an individual's personal discipline, it is tempting to ask the gross weight used by the f/o, this should not be done.
I had assumed that after EK 407 that this was how most airlines did things. I would be very interested to know if I am wrong.
Interruptions and chatter on the flight deck during set up is also a threat and ground staff/ cabin members need to be disciplined in this area.

[Heathrow Harry]

KENV wrote

"A system with that level of precision is really easy to design and build.

A system with that level of accuracy under all loading conditions over several years of service? Not so much."


You are correct - but I think that someone like Mr Dyson could come up with something new and accurate pretty quickly - it isn't rocket science

The problem is that no-one sees it as a real prioirity

[WingNut60]

KENV : Nothing that occasional re-calibration wouldn't fix.


But I would still see it only as a double check (treble check?) against existing procedures

[Chu Chu]

Rather than adding hardware, couldn't the existing computers be programmed to compare the aircraft's actual acceleration to that predicted? Surely the existing sensors are accurate enough to permit detection of a major weight error early in the takeoff roll.

But as SLF I have no idea whether this would be solving a real problem, or whether additional automation would just exacerbate the underling problem (if there is one).

[Capt Turbo]

Interruptions and chatter on the flight deck during set up is also a threat and ground staff/ cabin members need to be disciplined in this area.

Here you have the root cause: The last 5 minutes before STD/push back are the most stressed phase of flying, and the load figures often come at the last minute.
In most of "my" airlines I have seen how the stress makes the guys load-shed during the calculations. Why? Because there isn't enough time if you want to leave "on time", and OTP is the big mantra in most airlines.

In one airline we came up with a smart system: If you entered a GW less than MZFW it would block and give a warning. One day the crew attempted to enter the ZFW iso TOW, and when the warning came up they simply did an override. Result: Very close to disaster and a big hole in the tail. This is what pre-departure stress can do to you.

The OBAWS (Onboard Balance & Weight System) has been around for ages and is an excellent x-check reference, but the "Safety-is-our-main-concern" managements are very reluctant to pay the several thousand dollars for a system that does not bring revenue and whose sole purpose is to catch mstakes made by the excessively high paid pilots.

The last line of defence is the Speed Trend Vector found in most modern aircraft. If you don't accelerate 4KTS/sec you are unlikely to become airborne in 3000m, so you either go TOGA or abort.
During SIM trials in a widebody quad I gave the crews wrong figures which only gave them 60% of the required acceleration: They all overran the runway....In the 2nd attempts (and after a briefing) they all survived when going TOGA when they identified the slow acceleration (around 80-100 kts) - and they did not scrape the tail (but some close calls).

PS: The frog discussion is rubbish. I have checked several AF crews and they perform better than the average, but as with most of the old legacy carriers complacency is hard to eradicate. Not a unique AF issue.

[Basil]

The OBAWS (Onboard Balance & Weight System) has been around for ages
Yup. Had it on the B747-200F - but it was disabled because it cost too much to maintain :hmm:
I believe that the system on the -400F was better and more reliable.

[CaptainProp]

BTW, answer to post 26: a LOSA audit is being done as we speak, the second one in 3 years. And for the halfwits tinking like post 27, the B777/744 fleet manager offerded his resignation yesterday.

This is being taken seriously.

Well I guess there's a first for everything.
Nice attitude by the way, AF flight crew?

[RatherBeFlying]

One would like to think that the fancy new load and thrust calculation programs could produce a time to V1.

[BRE]

Quoting ATSB report about Emirates weight/speeds errors on Melbourne take off (100 t error):

Incorrect weight 262.9 t : V1=143 VR=145 V2 = 154 FLEX temp = 74°
Actual weight 362.9 t : V1=149 VR = 161 V2=173 FLEX temp = 43°

In previous 2 months, pilots used 3 A340 types, weight ranging from 150 to 370 t and quoting one pilot, numbers are loosing their meaning, they become only numbers...

Still bingo ?


Shouldn't 74° temperature have been a clue?

[Dairyground]

One would like to think that the fancy new load and thrust calculation programs could produce a time to V1.

I made a similar suggestion in a previous thread on this theme, but got the response that monitoring the tiome to V1 would put too much extra load on the PNF.

[framer]

Well what about a time to 80kts then?

[glofish]

The 77L in its freight version has some very special characteristics that make any 'gut feeling' or 'V-speed vs. weight dead reckoning' difficult.

As it is equipped with the 110lbs GE90 engines but the short body and a very light DOW, the Vmc on ground and in the air is extremely delicate. Imagine an empty flight TOW (145 tons absolutely possible vs. max TOW 347t) one can imagine what an engine failure and subsequent max power on one of these power plants means aerodynamically.

Therefore the Vmin's for such take-offs and landings requires speeds in excess of up to 20kts more than what the weight might normally dictate. The same effect happens with the assumed temperature, which remains fairly low in such cases.

This is not to excuse the crew, but it makes error detection with techniques mentioned in many contributions above quite tricky.

Cross qualified flying with animals so different in weight and characteristics, as well as a huge spread of cockpit equipment will always lead to errors. The Airbus 32/33/34 family has a long history and now the T7 family joins with ever more versions of airframes, engines and cockpit equipment. The trapping of errors is that much more demanding. Including more calls or time checks during take-off, or a quadruple crosschecking during calculations only increase workload and shed the initial shortcomings like short cuts in training, lack of basic experience and most urgently fatiguing rosters.

[KenV]

KENV : Nothing that occasional re-calibration wouldn't fix.

Occasional? Keeping the system up and accurate requires more than occasional maintenance.

Then look at it from a manager's point of view. What does this system do, REALLY? It backs up the pilot/FE to a make sure they made no gross errors. That's a lot of expense to check up on pilots that cost the airline a lot of money. Putting in a good procedural cross check (rather than a hardware cross check) is likely more effective AND cheaper.

[KenV]

Earthmoving trucks have had loadweigh systems for quite a while.
Pressure transducers in the struts and a control (summing) module - not such a great expense.

True. But what does this system do? It prevents overloading the truck and damaging it from overload. Not a great deal of precision or accuracy is required. That's not what the aircraft system must do. It must provide both a fairly precise and accurate total weight that directly affects take off performance. If the truck is too heavy and climbs up a grade or accelerates more slowly than expected no one dies. If the airplane is too heavy and climbs or accelerates too slowly, LOTS of people can die.

And more than just weight is involved. For the airplane, CG is involved. Many of the same weight numbers drive the CG calculation. And unlike the truck, improper CG can kill people on an airplane. (Witness NA Flt 102)

[WingNut60]

KenV :

Please don't cherry pick.
I also said "But I would still see it only as a double check (treble check?) against existing procedures".

I did not suggest at any time that it could be used as a replacement for proper calculation.
At least until more sophisticated systems are developed.

However these systems are actually quite accurate and reliable.
Like everything else, they need maintenance and checking (or as I flippantly said, occasional re-calibration).
But more to the point, if your manual system is so bl...dy foolproof then why has there been two or more recent cases of such major, and potentially fatal, errors.

Even a poorly calibrated loadweigh would pick a 100 tonne finger fault.

[ShotOne]

Capt Turbo's post hit the nail. These calculations nearly always have to be done in the five minutes before departure as that's when the load Figures come, and in some airlines the performance computer is also the electronic tech log, which is grasped in the engineer's oily hand until then. There are usually dispatchers, cabin crew, push-back crew, engineers, "on-time managers" (really!) and ATC all competing for attention so the flight deck is anything but a place of quiet concentration.

[KenV]

KenV :Please don't cherry pick.Didn't realize I'd done that. Sorry.

I did not suggest at any time that it could be used as a replacement for proper calculation.I did not realize I suggested you suggested any such thing. Sorry I gave that impression.

However these systems are actually quite accurate and reliable.
The ones I've been involved with weren't either accurate or reliable. Nor were they easy or cheap to maintain.

But more to the point, if your manual system is so bl...dy foolproof then why has there been two or more recent cases of such major, and potentially fatal, errors.I did not realize I had called the manual system bl...dy foolproof. Sorry I gave that impression. As to why there have been errors, the reasons are varied, but most relate to imperfect humans trying to do precise and detailed work in a pressure cooker environment.

Even a poorly calibrated loadweigh would pick a 100 tonne finger fault. Maybe. Maybe not. It could also indicate a 100 tonne error when there was no error at all. When you have an unreliable mechanical system that generates false alerts, it gets ignored. Perhaps that's worse than no mechanical system at all.

[framer]

Can any of you tell me if you do your performance calcs 100% independNtly from your offsider? On a different iPad/tablet/scratchpad etc ?

[WingNut60]

KenV:


OK .. back to civility .. sorry if I bit a touch hard.


Are there no pressure transducers in the struts now?
I'd have imagined that strut pressure would be a logical parameter to monitor other than for load weigh reasons.
How does WOW work on later aircraft? Surely not still through squat switches.

[KenV]

Are there no pressure transducers in the struts now?
I'd have imagined that strut pressure would be a logical parameter to monitor other than for load weigh reasons.


Landing gear are complex and the load paths more so. It is hard to know exactly which paths all the loads take under all conditions, making consistently measuring those loads difficult, especially when the ground is not perfectly level/smooth and/or there are high winds/wind gusts.


How does WOW work on later aircraft? Surely not still through squat switches.The squat switches have been replaced by prox switches, but otherwise, yes, it's still done like it was decades ago.

[TineeTim]

Framer- EK now do independent calculations. The procedure is almost identical to what you described you use.

[Heathrow Harry]

"especially when the ground is not perfectly level/smooth and/or there are high winds/wind gusts."

Ken - you are of course correct if you are looking for absolute accuracy but what is needed is something to catch the really bad mistakes - the factor of 2 or 10 - not a super correct engineering solution correct to 100kg

Some sort of averaging should work fine

[KenV]

You are correct, it all depends on what you want the system to do. If all you want to do is catch a big mistake, a simple system will do. But such a system will be wrong almost all the time. And any system that is wrong almost all the time will be ignored, defeating its intended purpose.

[silvertate]

Landing gear are complex and the load paths more so. It is hard to know exactly which paths all the loads take under all conditions.


Hardly. You have three, four or five legs, each with an oleo pressure. Its not rocket science to deduce a weight and balance from that.

And you could always zero the weight on a turnaround, when the aircraft was empty. The system knows the fuel weight, so can give you a 'lowest turnaround weight', and you just click 'yes' if the aircraft was empty on that turnaround.

Jezz, if the venerable old Belslow frieghter could have an automatic weight and balance check system, I am sure a modern airliner could. We appear to be going backwards, not forwards. As usual, it all comes down to cost.

[KenV]

Hardly. You have three, four or five legs, each with an oleo pressure. Its not rocket science to deduce a weight and balance from that.LOTS of loads go through the drag links and cross links and not just through the oleos, especially on non level or uneven surfaces, . Second there is significant stiction (static friction) inside the oleos. The oleos do NOT behave linearly. Measuring the oleo pressure gives a gross approximation, not an accurate weight.

As for cost being the driver, no, that is not true. Yes, it is a significant influence, but NOT the driver. An automatic weighing system would be a god send in a military freighter that operates from austere airfields. Neither the C-130 or C-17 have an automatic weighing system because they are simply not reliable enough. I cannot confirm it, but I'm pretty sure the A400 does not have one either.

[BARKINGMAD]

"A formal ritual involving both/all pilots present on the flight deck, sterile flight deck with no distractions from CC or ground staff, would help to stop this one dead. So would the practise of calculating, by brain, a gross error Vspeed, viz V2, from the CFP and annotating the CFP with it at the briefing stage, then comparing when finally loaded in the flight deck.

There, that's my pennyworth of problem-solving. I look forwards now to the inevitable flood of widgets, gadgets and software mods proposed by all the wannabe aircraft engineers/pilots out there, knowing that even if such hardware/mods get approved for use, it will be years before they are incorporated in ALL 'frames."

JUST THOUGHT I'D REPEAT WHAT I SAID IN POSTING #4, before the discussion descended into a foreigner-bashing session. Proof positive of how easily we all get distracted?? :ugh:

[framer]

"A formal ritual involving both/all pilots present on the flight deck, sterile flight deck with no distractions from CC or ground staff, would help to stop this one dead.
Yip. I agree , especially if emphasis is put on the importance of the calculations being made independently with a comparison only occurring once the final result is at hand.
Also, often times now days the ground staff are on minimum wage, minimum training, maximum workload ( turning more aircraft than they used to) and have no idea that distraction on the flight deck during this phase can be lethal so it is up to the pilots to enforce this sterile flight deck environment if the cabin crew don't. It is another example of how safety is slightly reduced each time an accountant has another brilliant idea about " lean operations" and implements it with no real understanding of what makes airline flying safe. I am all for efficiency and working hard but we are reaching a point where our enviable industry safety record will be tarnished on a regular basis if we don't act ( read spend money) when our SMS 's start squawking.

[MrSnuggles]

What if the French took to heart what everyone else is just bragging about. They actually REPORT the mistakes and incidents that happen. BEA even releases a little paper on reported mistakes and incidents from time to time.

So what if this thread exists just because AF learned from AF447 and since then started the reporting trend...?

I am 100% sure that if regulators in other countries was as efficient in getting reports, we all would feel a little scared. Some LCCs spring to mind. I know one where a CC fell out of an open door and right onto the tarmac. Now that's what fairy tales are made of.

So, may the odds be ever in your favour.

[phiggsbroadband]

Quote...
And you could always zero the weight on a turnaround, when the aircraft was empty. The system knows the fuel weight, so can give you a 'lowest turnaround weight', and you just click 'yes' if the aircraft was empty on that turnaround.


I think you need to re-define 'Empty'.... The galley will always have some food and water, the tanks will not be dry, and there may be hidden engineers lurking in the recesses.

[stilton]

Don't some models of the B747 freighter have a self weighing system as an option ?

[framer]

Thats interesting Stilton. Can anyone give us more information about self weighing systems. Are they precise? Are they reliable? How often do they need maintenance and could they be zeroed during turn around even if Engineers are aboard? Also, has a system like this ever been fitted to an earth moving truck?

[ShotOne]

Several folk have asked whether there's an independent check with the other pilot, to which the answer should always be yes. Of course it's never COMPLETELY independent; both calculations rely on the same load sheet. Yes they are quite often wrong. But for some reason this never makes headlines the way a mistake by a pilot does, and the dispatcher who used to be a key person capable of filtering some of these mistakes is now likely to be a min-wage school leaver. Also, electronic loadsheets are calculated to a spurious accuracy which makes a gross error less likely to stand out. For instance the trim setting may be given as 45.92 even though the trim can only be set to whole numbers

[EMIT]

Errors like the 100 ton mistake, the ZeroFuel Mass into Gross Mass input boxes, etcetera, are HUMAN FACTOR errors.

Wire somebody up for a brain scan of some sort and show him a picture of any kind of snake - his brain will show signs of ALARM all over the place.

Show him a picture of a sort of keyboard or piece of paper with numbers on it - his brain may show some activity in regions connected to arithmatic processes or text interpretation processes, but there will be NO TRIGGER OF ALARMS AT ALL.

Mankind is conditioned through millions of years to the danger of snakes, or lions, or other DANGEROUS creatures of nature and INSTICS will cause us to err on the safe side in case of doubt - oh, it was only a piece of black electric wire ....

Mankind invented typing , computers, keyboards, etcetera less than a century ago and even though a simple typing error of one wrong digit can bite you in a deadly fashion, our instincts have not yet adapted to that sort of monsters ...

First, man has to realise the deadly danger of errors in the complete process surrounding T/O performance and then he has to stick religiously to procedures that must ascertain independent calculations of which the results must be compared.

Addition of more automatic bells and whistles is not the magical pill to stop the errors from occurring.

Awareness of the danger and discipline in execution of correct procedures are the key.

And yes, in the big world with many different companies, improvement of procedures or layout of information may be necessary to be able to speak of "correct procedures".

[silvertate]

Phiggs

think you need to re-define 'Empty'.... The galley will always have some food and water, the tanks will not be dry, and there may be hidden engineers lurking in the recesses.


Sorry, chum, but the galley, water and crew are all included in the empty weight, while the FMC knows the fuel amount and the nominal empty weight (APS weight). And if you think that a few engineers and loaders are going prevent the system from spotting an error of several tonnes, you need to send your engineers on a fitness course.

Meanwhile, KenV's absurd suggestion that the oleo torque links take the weight of the aircraft must take the 'aircraft anorak gibberish' award for 2015. Thanks, KenV, you have just confirmed that the closest you have got to an aircraft are the models on your mother's dressing table.

[ShotOne]

The whole self-weighing argument is a little bit of a red herring since weight (ok, mass, if you're being picky) is only one of a number of factors which could produce erroneous take-off data.

[latetonite]

All attempts to make an airplane pilot proof failed so far.

[Intruder]

So have all attempts to make the perfect pilotless airplane...

[latetonite]

After All, Flying remains a profession, no?

[ShotOne]

Those comments are a bit silly; surely it's worth examining -and perhaps redesigning the tools given to pilots so that a very minor mistake isn't catastrophic? What about an electronic version of the old paper tables? The issue with the current accountancy-based programmes is they give no visibility of the effect of inputs or how close to the limit you are; empty sector or 1kg below MTOM it's either green numbers OK or Amber if over.

[RAT 5]

surely it's worth examining -and perhaps resigning the tools given to pilots so that a very minor mistake isn't catastrophic?

Surely it's already done? There is a flight plan with the ETOW base on pax figures and cargo. Then comes the load sheet ands the FMC loading. There should be a gross error X-check. There are the tools.

[ShotOne]

No it's not. The flight plan weight is an estimate/guess made at the point the plan is produced. It's never identical and can be quite significantly different to what you depart with. In any case as I pointed out earlier, weight is just one of many factors which could make nonsense of the performance calculation.

[framer]

I doubt any of these incidents have happened when the figures were calculated independently by each crew member. i don't think hardware or software is the problem or that changing either will solve the problem. The problem lies with the Human and can easily be mitigated by the Human.

[Intruder]

It is just like any other facet of aviation: Any human might make an error at any time. Through hard lessons, we have developed procedures and crosschecks to minimize the probability that a single error will be catastrophic. However, we must follow those procedures and perform those crosschecks to continue the chain.

While the Dispatch Release may not have an accurate final weight, it is unlikely to have a 100 Tonne or 100,000 lb discrepancy. Safety margins will likely render 10-Tonne errors harmless, and procedures such as dialing in a preliminary V2 into the MCP based on the flight plan weight should alert to a large error.

[ShotOne]

Preliminary V2? So you're advocating another entirely separate performance calculation based on the estimated take off weight? That figure, remember is a guess made several hours before departure. Aside from making a period of high workload even higher, what would that achieve? And why do all these helpful suggestions relate only to weight but none of the other inputs critical to correct figures?

[Intruder]

Setting the preliminary V2 has been a procedure in my airline for 15+ years. You don't have to do a complete performance calculation to get it -- looking at the Vref chart for the proposed takeoff weight is sufficient, or enter the takeoff weight into the Approach page. Can be done in 10-15 seconds. With a TLR (preliminary performance report attached to the dispatch release), just read the V2 off the sheet for less time spent. So don't make rash assumptions about what I am advocating.

And yes, many of the other "inputs critical to correct figures" are made prior to knowledge of the final figures, to include PROPOSED runways, departure, route, altitudes, and arrival. There are procedures and crosschecks for all. You don't wait for your final oceanic clearance before putting the route into the FMS; and when you do get the clearance you crosscheck with your filed route. Same with PROPOSED altitudes and winds to generate a fuel burn schedule...

Finally, we require an entirely new dispatch release if the actual ZFW is more than 10 Tonnes above the original. As I indicated earlier, a 10-Tonne error (in a 747) is survivable due to safety margins if an error is carried forward.

[ShotOne]

Whoa, you've rolled in a whole load of issues there, intruder and even though I agree with quite a lot of what you say it doesn't necessarily bear on the topic. It sounds like your airline has a robust set of procedures. Good. Also an entirely different set of tools to what AF (or I) had available. You referred to V ref chart?? In most airlines using laptop computer performance it is designed as a stand-alone device not used in conjunction with any chart. Presumably you have a set of charts covering all your destinations? With stand alone computer performance there is no "quick check" like you describe. Either complete a full calculation with a parameter in every box or don't do anything.

[Intruder]

Surely you have SOME kind of reference charts in your QRH and/or FCOM! If your computer fails airborne, are you unable to land?

I have done manual performance charts, standalone performance computers, and ACARS-downloaded performance in the 747 Classic and 744/748. In all cases there are/were backups available. Using a standalone computer is NOT an excuse for a failure to have a crosscheck process in place.

You mentioned earlier "an electronic version of the old paper tables". If you have an FMS, you have one. Enter your Flight Plan takeoff weight into the Approach Reference page, and it will give you a Vref for that weight. For the 744, Vref for Flaps25 is within a couple knots of V2 for Flaps10, and Vref for Flaps30 is within a couple knots of V2 for Flaps20. If the V2 from your computer comes up with a lower number, find out WHY! You can certainly come up with a similar crosscheck for your airplane.

You are supposed to be a professional pilot. While you follow standard procedures, you neither follow them blindly, nor become so procedure-bound that you do not understand what the procedures are supposed to accomplish and/or are unable to perform critical crosschecks.

[framer]

You are supposed to be a professional pilot.
Comments like that are more and more common on prune and are derisive.
What it means for everyone who is interested in the actual topic is that the thread goes off rails as two people start bickering and develops a toxic feel.
As for entering in the flight plan take-off weight in the FMS as a cross check. My company would frown upon that. I'm not saying it's a bad idea, just saying that what seems like a good idea to some is not seen in the same way by others. At our Airline the effort is put into ensuring that the two calculations are done 100% independently in a sterile environment. When we started doing it a month after EK407 I was surprised at how often one of us would have a different assumed temperature and we would go back to the drawing board. As a pilot group we have become better at it over the years because nobody wants to be the guy with the wrong figures .

[Intruder]

As for entering in the flight plan take-off weight in the FMS as a cross check. My company would frown upon that.
It is also a matter of WHERE in the FMS you enter it...

In the Approach Reference page, the weight entry is temporary - it is erased as soon as you leave the page. Once the ZFW is entered into the Init Ref page, the Approach Ref page defaults to the current gross weight, but that can be temporarily changed to any value without affecting anything else in the FMS. The Vref values are directly calculated from that entry, though, and can then be entered into the FMS or simply referenced for purposes other than approach planning.

When we first got the 744, that method of crosscheck [of our paper performance charts] was also 'frowned upon', but as people started understanding the airplane (and we started moving away from paper performance charts 10 years later), it became an 'official' means of crosscheck.

[ShotOne]

So in summary, your check of take-off speed and config relies on calculating an APPROACH speed for a different flap setting?? Is that a manufacturer approved process? It certainly isn't for any type I've operated. Allowing for your not especially polite manner, I'm pleased if this works for your type but even if some clever person were to work out similar rules-of-thumb for other types (in my case, A320/1/330) it would offer no protection against, for instance, even a fatally inappropriate flex.

[hitchens97]

A couple of questions from SLF...

1) What's the rationale for using less than 100% power at take off? Other than cost, is there something else? Like you're more likely to have engine failure, or the performance characteristics make it more difficult to fly?

2) Given the plane knows the start and end destination in its avionics, couldn't it at least alert a weight that would seem way out of the norms when input?

3) Given the avionics know runway length, pre-set power, and V1 couldn't the avionics suggest an abort of takeoff if the performance characteristics seemed significantly out of bounds?

[framer]

Checking Vref is a valid way of ensuring that the weight in your Performance Tool is the same weight that the FMC is using.
1) What's the rationale for using less than 100% power at take off? Other than cost, is there something else?

Not to my knowledge. It all comes down to cost. It actually burns more fuel to take off at less than full thrust, but the savings related to engine wear outweigh this. It is totally up to the pilots to decide when to use full thrust. An example might be when there is a gusty cross wind or windshear reported.
2) Given the plane knows the start and end destination in its avionics, couldn't it at least alert a weight that would seem way out of the norms when input?

More often than not the weight in the FMC is correct, it is the weight in the laptop or IPad that is incorrect and not in any way integrated with the aircraft so no warning is possible.
3) Given the avionics know runway length, pre-set power, and V1 couldn't the avionics suggest an abort of takeoff if the performance characteristics seemed significantly out of bounds?
FMC may not know the runway length, does not know pre-set power, and does not know V1. These are entered by the pilots after doing calculations on an iPad or a laptop or manually from a book.

[Tester78]

3) Given the avionics know runway length, pre-set power, and V1 couldn't the avionics suggest an abort of takeoff if the performance characteristics seemed significantly out of bounds?

The A350 does this, in broad terms. The Take-off Surveillance Function alerts the crew if the required lift-off distance is greater than the runway length ahead.

[Intruder]

it would offer no protection against, for instance, even a fatally inappropriate flex.
...and it is not designed to do so. As framer indicated, the FMS is not a complete takeoff performance computer. However, it CAN be used to crosscheck several aspects of takeoff performance. While the FMS may generate rough V speeds for takeoff, for example, we still use a dedicated performance computer to refine them.

Once again, you are supposed to be a professional pilot. Your knowledge of the airplane, its capabilities, and the environment should be a key factor in assessing whether any calculated thrust reduction is sane for the circumstances. Blind acceptance of automated tools is not good for your health.

[ShotOne]

"The FMS is not a complete take-off performance computer" Agreed. And that's an understatement. And if Mr Boeings product liability department saw it touted as such they'd have kittens. That's not to say it can't offer a useful cross-check against SOME parameters; but it's not something which was in the toolbox of the subject AF crew, -or any type I operate and hardly justifies your spiky jibes.

[Willit Run]

Its really quite simple:

S L O W D O W N !

We are paid by the hour, (well, most of us are).
Speed does not make you a good pilot.
Very little in this profession needs to be done in haste.

[JammedStab]

This one was Corsair...


Location: Paris, France

History of the flight:

On 10 December 2006, a Boeing 747-400 aircraft, registered F-HLOV, was being prepared for a scheduled passenger service from Paris-Orly airport, with 15 crew and 563 passengers onboard. On arrival at the aircraft, the crew found that the battery of one of the two BLT’s used to calculate the take-off performance parameters was flat; consequently, the second BLT (operating on battery power) was used.

During the pre-flight preparations, the first officer noted a fault message relating to the hydraulic circuit. Discussions with the ground mechanic determined that the issue was being dealt with.

When determining the take-off performance parameters for the flight, the captain provided the first officer with the ZFW from the weight and balance sheet, which he increased by 1.6 tonnes, and the TOW. The first officer then entered the ZFW into the FMS. The TOW was entered into the BLT and the take-off performance parameters calculated. The first officer handed the BLT to the captain to crosscheck the calculations. The BLT then went into standby and the captain handed it back to the first officer who unintentionally turned it off, thus erasing the entered data. At the same time, the captain was dealing with the hydraulic failure issue with the mechanic in the cockpit.

When the new data was being entered into the BLT, the captain inadvertently called out the ZFW instead of the TOW. A weight of 242,300 kg was entered into the BLT instead of 341,300 kg. The captain entered the resultant BLT data into the FMS, replacing the values automatically calculated by the FMS. The first officer then verified that the BLT and FMS values were identical.

The captain entered the assumed take-off temperature into the FMS and queried the reduced thrust value with the first officer. The first officer justified these figures by the fact that the QNH was high and the temperature was low.

The crew performed a rolling takeoff and did not detect that the aircraft’s acceleration was lower than normal. At the V1 speed, the crew noted that there was a reasonable amount of runway length still available and they began to doubt the V speeds. The captain (the pilot not flying) elected to delay the aircraft’s rotation.

When the first officer began the rotation, he immediately noticed that aircraft appeared heavy. The aircraft’s pitch was increased slowly, but the stick-shaker activated. The first officer responded by reducing the aircraft’s nose-up attitude and applying full take-off power. Ground personnel noticed smoke during the aircraft’s rotation.

After the takeoff, the crew suspected a problem with the calculated V speeds and increased the retraction speeds for control surfaces by 20 kts.
Contributing factors

The following factors were identified throughout the subsequent investigation:

•The ZFW was inadvertently read aloud and subsequently entered into the BLT instead of the TOW, resulting in V speeds that were too low

Take-off performance data
Data BLT calculation FMS calculation
TOW 242,300 kg 341,300 kg
V1 120 kts 147 kts
VR 127 kts 159 kts
V2 140 kts 169 kts

• The BLT was not connected to the aircraft’s power source and it went into standby mode.
• The captain was dealing with a hydraulic failure at the time the take-off performance calculations were being calculated.
• After the data had been entered into the FMS, there was no requirement for a comparison to be made with the TOW and the flight limitations.
• There was no requirement to compare the data entered into the BLT with the data entered into the FMS.

[JammedStab]

This one was AF...

Airbus A340: July 2004

Location: Paris, France

History of the flight:

On 14 July 2004, an Airbus A340-300 aircraft, registered F-GLZR, was being prepared for a passenger service, departing from Charles de Gaulle Airport, France. In preparation for the flight, the crew received an expected TOW of 268,600 kg, which was close to the aircraft’s maximum take-off weight (MTOW) of 271,000 kg. The TOW, rounded up to 270,000 kg, was used to submit a take-off data calculation request via the ACARS. The resultant take-off performance parameters were verified by the crew.

Shortly after, the crew were advised that the TOW was 5,200 kg less than that previously provided, resulting in a TOW of 264,800 kg. As the change in weight was greater than 5,000 kg, the crew were required to submit a new ACARS request. When entering the revised TOW into the ACARS via the FMGS interface, a weight of 165,000 kg was inadvertently entered. This weight was close to the ZFW of 164,480 kg. The resultant V speeds and FLEX temperature were then entered into the FMGS. The captain confirmed the parameters; however, he did not detect the error as he read the MTOW from the ACARS printout instead of the TOW.

During the takeoff, the pilot flying reported the aircraft feeling heavy and noticed that the V2 speed was slower than the VLS speed (the lowest selectable speed, which provides an appropriate margin above the stall speed); take-off/go-around thrust was not applied. The aircraft sustained a tailstrike, with the fuselage remaining in contact with the runway for a distance of about 100 metres.

Contributing factors:
The following factors were identified throughout the subsequent investigation:
• A weight similar to the ZFW was inadvertently entered into the ACARS instead of the actual TOW, resulting in low V speeds.

Take-off performance data:

Data Required Used
TOW 265,000 kg 165,000 kg
V1 143 kts 129 kts
VR 153 kts 131 kts
V2 161 kts 137 kts

• The FMGS would accept unrealistic low V speeds without challenge.
• The FMGS did not compare the V2 and VLS speeds, despite the fact that both values were known before takeoff.

The following information is based on a translation of the Bureau d’Enquétes et d’Analyses pour la sécurité de l’aviation civile’s (BEA) investigation report. Some information may have been omitted or incorrectly interpreted through the translation process.

•The presentation of the parameter values on the ACARS printout may have led to some confusion in reading between the TOW and ZFW.
•The take-off briefing procedures did not require a comparison between the TOW and speed characteristics.

[Interested Passenger]

Stick one of these (http://gtechpro.com.au/) on the windscreen. completely standalone accelerometer, and just have a good idea of your plane's ideal 0-60. I'd guess you're usually around 10 seconds, so if it takes 14, either the handbrake is on, or you're down on power.
Should work on all types, the only real issue I can see is the lack of a cigarette lighter socket on the flightdeck:(

[Heathrow Harry]

or just use the stopwatch function on your watch a few times.............

start it at the start of the run and note it (not stop it) at say 60kt

[latetonite]

If you are not ready getting airborne after 40 seconds past TOGA, start worrying.

[exeng]

Try JNB on a hot evening in a 747-200 direct to LHR - 40 secs would not come close to cutting it.


Kind regards
Exeng

[latetonite]

But I would start getting vigilant anyway. Would you mind giving me a ballpark figure, in seconds, for your 747-200- on-a-hot-day-in-JNB?

[exeng]

Evening to you latetonite.

About 50 to 55 seconds if my memory is correct.

Of course a 4 engine aircraft is somewhat less sprightly on the take off roll than a modern twin due to the need to only meet a 25% power loss at V1.

So I agree with your comment about vigilance.


Kind regards
Exeng

[Dont Hang Up]

...and just have a good idea of your plane's ideal 0-60

The whole point about a balanced field takeoff is that there is no "ideal 0-60".

A lighter airplane has a lower Vrotate, but also a much reduced rejected-takeoff stopping distance due to both the lower Vrotate and the faster deceleration. In combination this all has a big effect on the required takeoff acceleration.

Consequently, even when weight planning is completely correct the aircraft may seem to have an extremely leisurely take-off acceleration. So realising that the acceleration is even less because the aircraft is too heavy is not necessarily something one can judge easily.

[N.B Speaking very much as a theoretician - not a commercial pilot.]

[aeo]

Just FYI the 747-8F has a Weight and Balance system. It gives real time GW, MAC CG, ZFW and ZFW CG. The WBS uses sensors mounted on the Landing Gear.

GW and MAC CG information goes to the FMC and IDS.

This info can also be read on the Remote dedicated display unit (RDDU) that lives on the Main Deck although ZFW and ZFWCG can only be read on the W & B Computer Display in the MEC.:D

[Heathrow Harry]

I can remember a 747SP out of SF on a hot afternoon loaded for non-stop to HK

We needed a calandar not a stop-watch to time the run - thank god we took off over teh Bay

[ShotOne]

Again, the debate has become fixated on weight. With a computer performance programme, typically fifteen or so items of data have to be entered, of which weight is just one. A single mistaken or transposed digit will make nonsense of the end result. The only fatal instance that I'm aware of was the Halifax 747 where their mistake was to make the calculation based on the previous departure airfield to which the laptop had defaulted. As with the Emirates tailscrape, fatigue played a major part; the fatal flight was the return sector for a second Atlantic crossing in the same duty period.

[framer]

I'm pretty sure from memory that they said fatigue played no part in the Emirates accident in the final report. I stand to be corrected though as my memory sometimes lets me down .