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EFB and W&B

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Old 2nd Jan 2019, 10:03
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EFB and W&B

Apologies if this has been asked before but my search wasn't productive.

CASA says on their FAQ:

"Operators that intend to use software applications for weight and balance will need to have it validated by a weight control authority (CAO100.7). Performance applications will need to be validated by a qualified person and evidence of the validation retained for CASA review if requested."

So does this mean its ok to f*ck my calculation using pen and paper but it's unacceptable to use my EFB instead? Is this correct? Why would CASA be concerned about how I do my calculations?

Thanks, FT.
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Old 2nd Jan 2019, 10:15
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Your pen would be messed up on a piece of paper that otherwise provides the correct data.

The piece of paper has been approved.

Go to the EFB world now- the program (think paper) needs to be approved. You can still mess up on the data input (think pen).
if the software wasn't approved, you could be putting correct info into incorrect parameters, or wrong data into incorrect parameters.
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Old 2nd Jan 2019, 10:50
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Originally Posted by Car RAMROD View Post
Your pen would be messed up on a piece of paper that otherwise provides the correct data.

The piece of paper has been approved.

Go to the EFB world now- the program (think paper) needs to be approved. You can still mess up on the data input (think pen).
if the software wasn't approved, you could be putting correct info into incorrect parameters, or wrong data into incorrect parameters.
Well put Car Ramrod!
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Old 2nd Jan 2019, 11:48
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Yes, the paper is approved as well. The electronic entry or pen entry is irrelevant.
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Old 2nd Jan 2019, 11:51
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One of the concerns from the WCO's viewpoint is that testing and verifying the acceptability of electronic weight and balance programs is very involved if one is to be able to say, definitively, that the program will not give an incorrect answer. From a practical point of view, the testing would be commercially prohibitive for most operators to achieve a WCO's signature. Many years ago, I dabbled in software development for industry operators and, I have to say, I was horrified at just how innovative the end user could be when it came to finding flaws in program logic.

So how can we get around the problem ?

My view is that I will approve a suitable paper based system and am quite happy to include a rider that the operator may implement the approved paper system in a suitable electronic program providing that adequate software testing is performed by the operator to ensure accurate output. The approved paper system, though, remains the definitive approved Loading System. I note that a colleague adopted a slightly different approach for the operator of a 100-seat class jet .. there was a very extensive in-service test period using both systems. I guess that has some merit but remains an expensive exercise.

FWIW, I am amongst the most experienced handful of WCOs in Australia, and hold the first WCA issued back in mid 1976.

Why would CASA be concerned about how I do my calculations?

So long as you can demonstrate that your computer-generated outcome is functionally identical to the approved paper system, I doubt that CASA would have any real concerns. The secret, here, is to make sure that your electronic system replicates the approved paper system without trying to do too much in the way of additional fancy stuff. After all, the aim is to ensure that the aircraft remains within the approved envelope at all stages of flight .. no more, no less. If you want to do fancy stuff, do that separately and then link back to a basic mirroring program to tick the box for weight and balance as being OK.

This is particularly the case if your aircraft/operation doesn't require a load sheet per CAO 20.16.1.

If your question relates to having the WCO approve someone else's compiled electronic system other than one which mirrors his .. along with a whole bunch of bells and whistles, then all bets are off.
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Old 2nd Jan 2019, 21:14
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Originally Posted by john_tullamarine View Post
So long as you can demonstrate that your computer-generated outcome is functionally identical to the approved paper system, I doubt that CASA would have any real concerns.
That's the key to it. I generally use my own spreadsheet where I can see all the numbers and I can see that the numbers are the same as the AFM so I am using the spreadsheet to do the calculation as I would with a biro on the back of an envelope. I am taking responsibility for all the numbers and I can see/check all the data each time.

On the other hand I picked up my favourite EFB and clicked on the W&B for the type that I often fly and found many significant errors. The AFM, loading system and TCDS are in different units than in the EFB so it is not an easy task to check that the EFB data is correct. And up to date - there is a recent Service Letter amending a moment arm in the AFM.

If I operate through an organisation and have to use their spreadsheets or EFB they won't be expecting me to waste time checking the data or algorithms so if I am not taking responsibility who is? For W&B the only authority that I would accept is a WCO per the pic attached from the CAAP on EFBs.


PS: to clarify - I only comment wrt FAR 23 airplanes of not more than 6,000 lb maximum weight.
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Old 2nd Jan 2019, 22:46
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Originally Posted by Flying Ted View Post

Performance applications will need to be validated by a qualified person and evidence of the validation retained for CASA review if requested."
Curious, what is the definition of a "Qualified person"? Aeronautical Engineer? Pilot? The people in ops who prepare documents prior to dispatch (despatch if you like in the British English context)?

Originally Posted by john_tullamarine
From a practical point of view, the testing would be commercially prohibitive for most operators to achieve a WCO's signature
Having come from a software engineering background and having written software which had airworthiness implications for defence, I'm wondering how this was prohibitive? Given the WCO would be using a a tried and tested set of formulas for each graph, so it wouldn't take much to produce a test dataset of every permutation and combination of values which could be verified against the base formula.
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Old 2nd Jan 2019, 23:38
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Irrelevant questions I know, but...

How many accidents or incidents would have been avoided if W&B calculations had been done on an approved piece of paper rather than an unapproved electronic system?

If a pilot is willing to take the risk that W&B calculations done by an electronic system are not accurate, why would that same pilot bother to do accurate calculations using the approved paper system?

My experience is that it's pretty simple to confirm that calculations done by an EFB W&B system 'match' those done using the approved paper system, at the various extremes of the envelope. And on the paper system a pencil thickness can 'weigh' kilograms and accumulate to an inch of difference anyway...
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Old 3rd Jan 2019, 00:23
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I am taking responsibility for all the numbers and I can see/check all the data each time.

And that is the crux of the matter. djpil, apart from being a fine fellow, is both a very experienced and competent engineer and WCO and, without stating it in as many words, is taking steps to ensure that he can defend his actions before CASA or, far more importantly, in court, were a point to go that far for whatever reason.

Curious, what is the definition of a "Qualified person"?

I suggest, one who would be held to be an expert witness by a competent court of law (or hold the appropriate regulatory delegations or appointment as an authorised person by CASA) .. and that would include both djpil and me (although I think both of our CASA engineering appointments are now well lapsed).

Having come from a software engineering background and having written software which had airworthiness implications for defence, I'm wondering how this was prohibitive?

Likewise, I have had an extensive background playing with military stuff, albeit not in software design. The point of the discussion is who carries the PI for the activity ? The typical WCO is a one-man band and he/she needs to be darn sure that what is signed off will stand up to serious scrutiny in court. Been there, done that and very glad that I approach these things with a conservative philosophy. Those WCOs who might just sign off some unknown EFB software are, in my considered opinion, somewhere between very silly and very game.

Given the WCO would be using a a tried and tested set of formulas for each graph, so it wouldn't take much to produce a test dataset of every permutation and combination of values which could be verified against the base formula.

I don't have a problem with that comment for software developed by the WCO. However, if the WCO is going to develop the software, the problem, time and cost (as you would well know) lies in idiot proofing the software rather than the simple tech work. Again, although dated, I have been there and spent inordinate amounts of time so protecting software coding. Someone has to pay for that time and it isn't me. It might be fine for commercial software developers to hide behind the spurious claim "it's not a bug, it's a feature", but the PE and WCO can be hauled into court to defend his/her actions and work and is at risk of serious legal penalty .. think many dollars and, even, jail time. Hence my comment above - those WCO who might just sign off some unknown compiled EFB software are, in my considered opinion, somewhere between very silly and very game.

so it wouldn't take much to produce


Have you done so for a complex loading system on a larger aircraft ? No ? I didn't think so. Think mucho time and effort, keeping in mind the aim is nil defects, not just commercially acceptable output.

Dave, on the other hand, observes I picked up my favourite EFB and clicked on the W&B for the type that I often fly and found many significant errors. Surprise, surprise. Now I know from anecdotal information, that there are WCOs who sign off on EFB or similar software without more than a cursory check. Brave folk in my view. It is so easy to cover all bases and put the responsibility back where it belongs .. on either the owner or operator. This can be done quite easily for EFB style programs. Simply get the WCO to review the program, develop a paper based image of the box output and go down the same path as for home grown software. Alternatively, pay for the time in thorough checking and we can do that as well. It remains the owner's or operator's choice.

How many accidents or incidents would have been avoided if W&B calculations had been done on an approved piece of paper rather than an unapproved electronic system?

Moot point in the absence of investigatory data.

If a pilot is willing to take the risk that W&B calculations done by an electronic system are not accurate, why would that same pilot bother to do accurate calculations using the approved paper system?

Touché and very pertinent to the discussion, I suggest. But, then again, such pilots fall into the class of under-performing pilots.

My experience is that it's pretty simple to confirm that calculations done by an EFB W&B system 'match' those done using the approved paper system, at the various extremes of the envelope.

I'm afraid your experience doesn't quite cut the mustard in respect of what is required to be done.

And on the paper system a pencil thickness can 'weigh' kilograms and accumulate to an inch of difference anyway...


Unfortunately, many loading systems of a graphical nature are poorly designed and your comment is valid. However, design the system well and the problem fades into background calculation noise




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Old 3rd Jan 2019, 02:37
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There wouldn't be an Airliner on the planet that takes off to the exact figures calculated anyway! W&B in detail is mostly to satisfy the regs!
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Old 3rd Jan 2019, 05:00
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There wouldn't be an Airliner on the planet that takes off to the exact figures calculated anyway!

That applies to any and every aircraft - there are errors inherent is many aspects of weight control. That doesn't mean that we don't do our best to keep them under control. What is fair to say, though, is that the certification process gives you an aircraft which, if operated in accordance with design expectations (ie the AFM for the pilot) will provide you with a reasonably effective and safe piece of machinery. Diverge from the approved figures and you start to erode the fat. Diverge too far and you WILL end up dead. Now, do you know how far you can fiddle the figures ? Probably not ? Moreover, the discussion revolves around protocol, not departure accuracy.

W&B in detail is mostly to satisfy the regs!

Three things, I suggest, are of concern -

(a) design and operational safety and risk

(b) legal consequences if you get your bit wrong

(c) satisfying the Regs runs a distant third place.
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Old 3rd Jan 2019, 06:41
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I'm so glad you guys have posted this thread, you have inadvertently stumbled upon something I have known about for years, despite my best efforts nothing has changed. I will over simplify what I mean. So some performance software which was developed decades ago and properly certificated at the time has since been modified by programmers who may or may not know anything about aircraft performance, The training in its use becomes less thorough, simply because the person teaching you how to use it doesn't really understand it themselves. Then one day runway performance data is presented to a captain who knows his shit and knows exactly how his aircraft will perform both on one and two engines. he asks himself the question how is it this runway has no takeoff weight limit and no special procedure when I can see the obstacles and terrain sitting right there in front of me, off the end of this very runway. Be aware people, not everything is what is seems, despite the fact that the data was generated by an approved person using authorised software. This issue is in every australian airline today.. Beware.
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Old 3rd Jan 2019, 06:58
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Having been involved in scheduled performance since the early 70s I have to say you've hit the nail on the head .. at least for some cases.

In days gone by we cut our teeth on the slide rule and AFM performance charts - all done mandraulically. As a consequence the average performance engineer got to a point where he/she had a pretty good feel for an aircraft's capabilities.

More recently, the manual things have gone the way of the dodo and, while the engineers are no less potentially competent or capable, they haven't had the opportunity to have the exposure to the nitty gritty work.

Much the same can be said for old pharte pilots versus the current crop coming up. The former had a feel for things, having had to do stuff from paperwork. The latter have been treated unfairly by only getting to push buttons and, as we all know (I hope) GIGO often rules the day.
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Old 4th Jan 2019, 00:01
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My experience is that it's pretty simple to confirm that calculations done by an EFB W&B system 'match' those done using the approved paper system, at the various extremes of the envelope.

I'm afraid your experience doesn't quite cut the mustard in respect of what is required to be done.

And on the paper system a pencil thickness can 'weigh' kilograms and accumulate to an inch of difference anyway...
Unfortunately, many loading systems of a graphical nature are poorly designed and your comment is valid. However, design the system well and the problem fades into background calculation noise.
Yaabbut...

What more can I possibly do than use the “poorly designed” graphical system? And if the electronic system is confirmed as producing the same results as the “poorly designed” graphical system, in what possible ways can I gain experience sufficient to “cut the mustard”? Why else did I pay someone a lot of money to put a current and approved graphical W&B system in the flight manual?
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Old 4th Jan 2019, 00:57
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What more can I possibly do than use the “poorly designed” graphical system?

If you are a line pilot (which I don't believe you are from what I understand) then, not much. If you know a bit more than the average line pilot, maybe you can raise your hand to management and ask for a more appropriate loading system .. a good one is not much different in preparation workload than a bad one .. just takes a bit of interest and understanding.

And if the electronic system is confirmed as producing the same results as the “poorly designed” graphical system, in what possible ways can I gain experience sufficient to “cut the mustard”

It's a case of who purports to determine the adequacy of the electronic system. As djpil observed, sometimes the ostensibly you beaut, whizz bang , with all the bells and whistles app is a crock. Like the previous observation, the poor old line pilot is left a bit out in the cold and can't do much more than follow what the company puts in front of him/her. Certainly, the average line pilot will not be able to establish whether the app is good, bad, or indifferent.

Looking at some of the trimsheets out there, some are so dreadful as to be culpable. Some examples can be found in a thread on an Oz theory training site (https://www.bobtait.com.au/forum/rpl...g?limitstart=0).

If you (or anyone else) would like to up the personal ante to the point where you can review and assess loading systems, then you need to do some homework and study. Nothing terribly difficult but it needs to be done to acquire the competence. Judging by numerous comments over the years, I think I can say that some pilots have a very basic understanding of weight and balance .. and that, only, on a good day.

Why else did I pay someone a lot of money to put a current and approved graphical W&B system in the flight manual?

Ah .. now there's a problem identified. The WCO system, since inception, has been a bit average when it comes to loading systems. The rulebook (CAO 100.28) addresses light aircraft weighing and the simplest of loading systems. Unfortunately, many WCOs have had too much delegation when it comes to loading systems and are, frankly, way out of their technical depth. Indeed, CASA has a project on the go to address, inter alia, this problem. See https://www.casa.gov.au/rules-and-re...cer-and-weight.
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Old 4th Jan 2019, 01:06
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I have been dealing with this issue for years, the problem goes right back to the manufacturer. Open any product made in china and read the operating instructions and you begin to get the idea. The engineer who originally produced the document can’t check his own work because English isn’t his first language, he relies on interpreters who don’t necessarily know anything about the subject material. He may be able to speak English but not read and write English.

On top of that add another tier where different terminology is used, for example a prepared surface verses and unprepared surface (Europe) and a sealed surface verses an unsealed surface (Australia) A prepared surface is not necessarily a sealed surface and you begin to see the magnitude of the problem.
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Old 4th Jan 2019, 01:37
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for example a prepared surface verses and unprepared surface

In essence, the difference will relate to a different (presumed) friction coefficient which, of course, rarely is quoted in the final documentation.

If you get to the point of very soggy surfaces, it gets a bit more complex .. I recall an OEM report on some takeoff tests for the 748 for soft, deep, mud ... interesting. Would bring tears to the eyes of the 4WD muddies brigade. Still have it tucked away in the archives somewhere.
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Old 10th Jan 2019, 11:07
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Thanks everyone for the response. It seems most of the posts relate to commercial ops. Does CAO100.7 apply to private ops? Is it really this complicated to use a EFB to do a W&B for C172?
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Old 11th Jan 2019, 02:56
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Are you mad? Don’t you know how many accidents and incidents have been caused by C172 pilots using EFBs to do W&B calculations?
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Old 11th Jan 2019, 08:45
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Does CAO100.7 apply to private ops?

Yes, see CAO 100.7.1 in this link https://www.legislation.gov.au/Details/F2018C00475. Also CAO 20.16.1 comes into the act. See CAO 20.16.1.1 in this link https://www.legislation.gov.au/Details/F2018C00462 and CAO 20.16.1.3 in the same link. Likewise have a look at CAO 20.16.2 and 3.

Is it really this complicated to use a EFB to do a W&B for C172?

Not at all. However, a problem may arise with establishing whether the program proposed for use is valid .. or not. Refer to CAO 100.7.5.2.(2) in the link to see whence the procedural problem arises.

Unless you wish to expose yourself to censure, one needs to address these considerations. Providing you observe the loading system, you are reasonably well covered. I don't see a problem with developing a WCO workaround with a simple loading system which permits the use of an EFB to do the number crunching. Just make sure that the EFB is legit from a technical viewpoint.
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