Isn't it important anymore?

[old man emu]

When I designed the Flight Plan form for The Event, I included a section for recording fuel usage and another for calculating the weight and balance moments of the aircraft to check that the Total Moment was within the aircraft's W&B envelope.

 

I don't know if it was ignorance or lack of data, but most of the entrants did not complete the record of calculations for W&B. Most did put in the weights, but not the related Moment. Only one entrant actually noted the fore and aft limits of the Moment based on the  weights. Has this important safety and performance item ceased to be stressed? Have manufacturers stopped putting those graphs on the POHs? Have we adopted the idea that if we can close the doors, the loading is OK?

[facthunter]

I don't recall anybody who flew in convoy with me doing weight calculations.  Not that I checked but some did comment on me doing it.    I don't like flying in convoy much anyhow. More you have to look  out for.  Nev

[rgmwa]

I suspect very few weekend pilots routinely do W&B checks unless the loading is different to normal, in which case you would hope they would. I certainly do when heading off on a long trip and loaded front and back with a lot of extra stuff plus full fuel, but I don't when flying solo locally. I visually monitor fuel usage and fuel flow on every flight, but don't record it for local flying.  I do on a longer trip.  Of course as with everything, unless you do the paperwork regularly you get rusty. In fact, it wouldn't do me any harm to get my BAK and PPL books out again and get back up to speed, and I'm probably not the only one.

 

[turboplanner]

16 minutes ago, old man emu said:

When I designed the Flight Plan form for The Event, I included a section for recording fuel usage and another for calculating the weight and balance moments of the aircraft to check that the Total Moment was within the aircraft's W&B envelope.

 

I don't know if it was ignorance or lack of data, but most of the entrants did not complete the record of calculations for W&B. Most did put in the weights, but not the related Moment. Only one entrant actually noted the fore and aft limits of the Moment based on the  weights. Has this important safety and performance item ceased to be stressed? Have manufacturers stopped putting those graphs on the POHs? Have we adopted the idea that if we can close the doors, the loading is OK?

In answer to your question, Yes it is important, and your experience indocates we will see a few unnecessary deaths or injuries down the track.

 

I Understand you had a ic of RA and GA.

 

In RA, every time I've mentioned P&O there's been a deafening silence, but no one has openly come out and said P&O is not being taught and assessed by RAA.

 

If you don't know what you don't know, it's a lurking danger, but given one of our members lost control of a Morgan after putting his 15 kg in the wrong place, and another spectacularly finished in a heap at a Flying show, and a lot of RA pilots have had fuel exhaustions, I'd suggest there's an urgent need to close the gap.

 

In GA, despite the external testing of pilots quite a few still get lost and have fuel exhuastions and the ATSB reports include fatalities where W&Bs weren't done and the aircraft went nose up and then straight down on take off, or stalled.

 

And then there are those colliding with the ground in the mountains, and on our higher plateaus on hot days because they didn't calculate for altitude and temperature, or the grass resistance.

 

And of course Navigation where there are lots of very odd flying reports indicating the pilot was lots at some point.

 

All for the sake of three or four weeks of night sessions and walking away a much safer person.

[Bosi72]

I would've expected the w&b would be done on paper once for several options and kept with other documents. E.g.:

1. solo + full tanks + max bags

2. dual + full tanks + max bags

3. family + full tanks + max bags

and a PIC would know what are the max limits for particular aircraft.

 

Good thing is the EFB's these days offer the option to create own aircraft with datums and envelopes, so calculating any combination is a matter of typing the weights.

 

Be careful if importing an existing aircraft type, confirm that the datums and limits are matching your aircraft, because no two aircrafts are the same (eg. instruments, long range tanks, etc..)

 

 

 

 

 

 

[sfGnome]

I created an equivalent (presumably) to the W&B calculators in the EFBs (they didn’t have them back then as far as we knew) for the Tecnam so that every flight was automatically checked (and printed complete with calculations in case we were ramp-checked). We also checked that all extremes of us 3 pilots, passenger, fuel and load stayed within the envelope, so it wasn’t a major concern. Then again, as we were only RA, we apparently weren’t taught well enough to know what we were doing… 🤨

[Carbon Canary]

Well, I was meant to fly a C172 with 4 adults yesterday, but the XW at the planned destination exceeded my personal mins so the flight was cancelled. The flight would have been at MTOW with fuel load being restricted. I have an excel spreadsheet that plots the initial and final arms based on the A/C loading and positions and a printout goes with the flight plan in case of ramp check. Yep, I still use paper charts too !!

Fortunately with a C172, if you stay below max weight and load from the front, you would have to try pretty hard to get outside of the envelope.

Anyhow, to answer the question, I sincerely hope W&B is both taught AND routinely practiced in both GA and RA.  I recall seeing a photo on this site from a few years ago of an aircraft loaded to the gunnels with camping gear and the owner apparently skiting  that everything is fine if the aircraft can actually still takeoff.  I don’t know if that owner is still with us.

As with fuel calcs and in flight monitoring, since CASA introduced the new Mayday fuel regs, fuel management and inflight logging is even more important than it ever was……..again a ramp check would reveal all.  The risk in flying C172s is that you never need to change tanks and fuel management can get sloppy. I wonder if that is how some people forget to change tanks in a Piper and then gravity comes into play.

[old man emu]

Goodness! I didn't realise that this  W&B topic was not being taught, or if it is, not being practised. 

 

Is it that when we are learning to fly, it's usually an hour's flight with just an instructor and yourself so that the loading would never make the balance go out of the envelope? That introduces a habit so that later on, we don't consider balance if we use the aircraft for holiday trips. 

 

I also wonder if people are taught to consider the need to always be flying at cruise power. Do people ever think to decide on a suitable ground speed and see how they can use the wind to adjust their power setting. Maybe with the wind at your back, you can throttle back atad to and still get a normal sort of round speed.

 

Or am I simply an old fuddy duddy who likes the DIY approach to calculation and disdains to use some electronic gizmo?

[rgmwa]

I can only speak from my experience but the practical and theoretical training I received not that long ago at RACWA (late starter) was pretty thorough. W&B and fuel calcs were normal procedure for any nav’s, as you would expect, and also covered in test papers when doing AFR’s. All nav work was pencil, paper, whizz wheel and charts. I don’t know if they use electronic aids in training these days, but I’d be surprised if they didn’t still have a heavy emphasis on the old way of doing things. 

[Area-51]

It depends what is considered thorough... My RA training covered it within the theory books; and the GA training went into it a lot deeper, but both i thought covered the subject enough. 
 

The responsibility is on the commanding pilot, and i'm amazed how many take off without really checking.

 

As someone mentioned above, many pilots are weekenders flying the same fuel and pax loads... I was one of them once; calculating in my head my AUW Fuel and CG; knowing the combined limits from using charts in the beginning...

 

Then one stinking hot humid day with a pax on board a go-around was elected and with full power the bird was not climbing, so instead of panicking and pulling back on the stick i let the training take over, kept it low and clear of obstructions until 90kt came up and we were away for another circuit; it wasn't a laughing moment.

 

After landing i checked the W&B and found the CG was right on the forward limit due to lower fuel loading; and the humidity didn't assist any either.

 

So as a result every flight now gets checked for W&B for T/O and Final before taxi; even if i know its well within the box, it's part of my preflight. And if i need to strap 10kg of dead weight somewhere to balance things out i do it; what ever it takes.

 

 

[old man emu]

7 hours ago, Area-51 said:

I was one of them once

You were one of the lucky ones. Experience is a tough teacher. 

 

Another thing that perhaps gets overlooked is Density Height and its affect on performance. We might not have the heights to get over that the northern hemisphere people do, but our typical surface air temperatures and higher air pressures do need to be conidered.

 

However, sometimes these make for strange results. At sunrise on Saturday the air temperature on the aerodrome was 0C, air pressure about 1030 and aerodrome is 1300 AMSL. Would that mean aircraft would make submarine approaches?

[Carbon Canary]

I was part of a 6 ship safari to White Cliffs a few years ago, with one of the aircraft being a C172B.  The safari was in October and temps were around the high 30's for most of the trip.

We planned a lunch stopover in Louth on our way from Bourke to White Cliffs. The bitumen strip at Louth is long enough, but it was recognised the climb performance of the fully loaded C172B on a hot day would be a critical risk in getting back out.  The command decision was taken by the PIC to forget the stopover, overfly Louth and continue on to White Cliffs.

[aro]

I don't recall doing much performance or weight and balance in my RAA training. It was covered fairly thoroughly in PPL.

 

One of the problems in RAA might be that the results of the weight calculations might be embarrassing, at least for the older lighter aircraft (and even 2 seat GA aircraft like the C150/C152). I suspect there has been a lot of training performed overweight over the years. In GA you probably start learning weight and balance when you start doing navs, when you probably also switch to 4 seat aircraft where the weight isn't a problem.

 

8 hours ago, Area-51 said:

i let the training take over, kept it low and clear of obstructions until 90kt came up and we were away for another circuit

 

90 knots seems like an unlikely number for best rate of climb??

[facthunter]

Best rate is a higher speed than best angle of climb.. Cruise climb is often appropriate where the plane can still have a better G/S and still have an acceptable climb rate but that's slightly not what we are talking of. KNOW your planes critical speeds.  Nev

[aro]

True... both are likely to be lower than 90 for common RA aircraft. 90 kts would be for higher performance aircraft e.g. Cirrus, Bonanza are probably somewhere around there. For our aircraft (<45kt stall speed) somewhere around 65-70 seems more likely.

[Old Koreelah]

I would have failed OME’s W&B bit miserably, being a mathematical cripple! Moment arms and all the other terminology are a good way to bamboozle people like me (luckily there aren’t many of us!)

 

I have always struggled with calculations; discovering computer spreadsheets was life-changing!

My plane is the only one I’m ever likely to fly (other than during my BFRs) so I’ve built it to suit my requirements and limitations.

 

Although I made extensive use of spreadsheets during design and construction, I learned the hard way how easily mistakes can be made. The only way I could be sure of W&B safety was to test my plane sitting on a rolling fulcrum, trying every conceivable combination of fuel, luggage and pilot weight. The results are marked permanently under my wing and are well within the original designer’s parameters.

 

Because I installed wing tanks just behind the spar, going from empty to full makes little difference to the CoG.

That means I can fuel up, load my regular camping gear and luggage and know I’m well within the safe range.

 

[rodgerc]

17 hours ago, sfGnome said:

I created an equivalent (presumably) to the W&B calculators in the EFBs (they didn’t have them back then as far as we knew) for the Tecnam so that every flight was automatically checked (and printed complete with calculations in case we were ramp-checked). We also checked that all extremes of us 3 pilots, passenger, fuel and load stayed within the envelope, so it wasn’t a major concern. Then again, as we were only RA, we apparently weren’t taught well enough to know what we were doing… 🤨

Maybe it’s unique to me, but of all the “RA-Aus” pilots I know (14 come to mind, including myself) all but two are current or former GA, ATP or airforce pilots. 

[turboplanner]

10 minutes ago, rodgerc said:

Maybe it’s unique to me, but of all the “RA-Aus” pilots I know (14 come to mind, including myself) all but two are current or former GA, ATP or airforce pilots. 

There are 10,000 RA members, so yes it is a group where you wouldn't expect issues.

[facthunter]

What I found most  when I got into RAAus Instructing was the variability of the participants as to knowledge, aptitude (dare I use that term?)and background attitudes etc Older people have firmed up a bit on basics  and (also some of) the established AUF who were instructing would put ex ATPLS through the mill trying to find a chink in their Armor. Quite funny actually.  I did my first U/L flight in a 2 seat  Thruster at a Mangalore Airshow with a bigger audience than you need.  I flew the 300' circuit with a faster climb and approach but it was safe and unassisted.  People forget WE started off in Tigers and all over grass fields.  You don't forget how to ride a pushbike. Nev

[spenaroo]

2 seat, side by side. with the fuel in the wings is probably the majority of RAA aircraft.
which brings the question of what weight moment can you change?
if its under MTOW then that's pretty much all you can do. (excluding the small overnight bag you may be able to sneak in if your not at MTOW with full fuel load)

I know the J160 couldn't take full fuel with two 90kg people. all the added load of fuel and people was under the wings (center of lift)
Vixxen was similar, but might have the ability to take some sandwiches and water bottles too.

The other aircraft I have flown in RAA is a tandem seat with the fuel in front of the firewall.
once again question is how heavy is the back seater. cant change where the weight is, and no room for more then an overnight bag.

 

I was taught it all as the theory course I did was mixed with RPC/RPL students.

but with the RAA aircraft it was a question of fuel load, possibly passenger and the density altitude.
MTOW was achieved well before needing to look at balance.

Edited May 23, 2023 by spenaroo

[turboplanner]

1 hour ago, Old Koreelah said:

I would have failed OME’s W&B bit miserably, being a mathematical cripple! Moment arms and all the other terminology are a good way to bamboozle people like me (luckily there aren’t many of us!)

I'd say there are thousands so you shouldn't feel bad; If the simple basics are taught and multiple exercises (where there the answer has been written so you know you're on the right track, then you'll know what they inputs are and what needs to be included.

 

Part of the confusion starts where the aircraft manufacturer either doesn't provide envelope figures and datums, or reinvents the wheel so you get the equivalent of learning French lanugage and being examined on Italian.

 

1 hour ago, Old Koreelah said:

 

I have always struggled with calculations; discovering computer spreadsheets was life-changing!

My plane is the only one I’m ever likely to fly (other than during my BFRs) so I’ve built it to suit my requirements and limitations.

That makes me a bit nervous because you have to know the figures you would calculate to load the key spreadsheet cells.

If, for example, someone else has built the spreadsheet for their aircraft, and you build one fitting the fuel tank in a different position, using more comfortable seats then the datums the spreadsheet is loaded with will give you an error for all calculations on your aircraft.

1 hour ago, Old Koreelah said:

Although I made extensive use of spreadsheets during design and construction, I learned the hard way how easily mistakes can be made. The only way I could be sure of W&B safety was to test my plane sitting on a rolling fulcrum, trying every conceivable combination of fuel, luggage and pilot weight. The results are marked permanently under my wing and are well within the original designer’s parameters.

This is a good way of countering the mistakes I mentioned above. 

If your equation inputs are accurate the end result on the aircraft will confirm that accuracy. If they vary you just check which way and re-measure, correct the spreadsheet and you're back with confidence.

I'm looking to get an error rate of zero kg.

1 hour ago, Old Koreelah said:

 

Because I installed wing tanks just behind the spar, going from empty to full makes little difference to the CoG.

That means I can fuel up, load my regular camping gear and luggage and know I’m well within the safe range.

 

Once you have done one W&B calculation, that can be filed and used for subsequent flights; you don't have to do the maths over and over again.

Similarly with school aircraft and students within a median weight and lessons being in the known Training Area, there's no point in doing a calculation every hour when they're all going to produce the same result.

However, there can be NO CHANGES for this to work.

There was a scare where I was flying at one point where two grossly obese men got out of an LSA55, and the school realised the aircraft was overweight.

 

Growth loads have figured in some crashes; where someone started going on camping flights and the gear started to include heavy swag, more food, tools, hunting gear etc to the tipping point.

 

One fatality involved a property owner who took his young son with him to borrow an implement part from a neighbour a fe kms away. By the time they got the part ready  (a)  they didn't weigh it and it was very heavy, and (b) the temperature had risen to more than 35 degrees. The Pilot couldn't get over the paddock fence so he bounced the aircraft and jumped over it and did that twice more, so three chances to put it down before he killed himself and his son.

[old man emu]

3 hours ago, Old Koreelah said:

I would have failed OME’s W&B bit miserably, being a mathematical cripple!

Honestly, with access to the several graphs present in a POH, there is no need to have even a modicum of arithmetic ability. Just follow the instructions in the POH.

 

 

Here is Page 6 of the POH from, admittedly, a factory manufactured aeroplane.  Start at the left hand axis (weight of object). Move from left to right until you hit the relevant line, then go vertically down to the bottom axis to get the necessary number.

 

 

Once you have all those numbers you add the wieghts to find the total load. Then you add the Moments to get the load Moments. You have to also obtain the aircraft's weight and moment from the handbook that is specific for the aircraft you are using, not generic. From this page, I would use the AOW which doesn't require you to accurately measure the amount of oil in the engine. Just check that it is to the "FULL" mark on the dipstick.

 

 

Once you have done those additions you go to the W&B envelope chart. Again, start at the left hand axis from the total weight and go across to the right. Go up from the bottom (index units) until you intersect the weight line. If the intersection is within the bordered area, you are OK. The area of the Normal Category on the graph includes the Utility Category, which is a restricted W&B combination that allows for more strenuous forcing of the airframe.  It is probably possible for the W&B  for a slim pilot doing a few circuits with, say, 1/4 tanks  to have the in the utility category area, but that's OK for the task of shooting a few circuits.

 

Here's something to think about. If your bladder can take it, and you decide to fly until you've only got your 45 minutes' reserve left in the tanks when you land, it might be possible that the W&B is outside the envelope. Who calculated W&B at the end of a flight?

 

[Old Koreelah]

All good points, Turbs.

To ovecome my mathematical ineptitude, I used speadsheets for every aspect of my build, carefully loading every component’s weight and its distance from datum point. Despite my careful efforts, the first design went way overweight, so I had to remove that engine and start again with a lighter one. Good experience, that resulted in a much better aeroplane.

A neighbour’s digital cattle scales were handy, but they can sometimes be misleading.

After the best measurements and calculations, it was still a good idea to put the whole plurry thing on a rolling flucrum, to be sure, to be sure.

 

A final point: about the value of having a partner in crime. Almost all my work is done solo, with nobody to bounce ideas off. When a sticky problem arises I tend to stop work and and move to a different project (I’ve got plenty on the go). This allows the subconscious to generate a solution.

It can takes a week or more to come up with an idea that a co-worker might have suggested after five minutes! 

[Area-51]

9 hours ago, aro said:

I don't recall doing much performance or weight and balance in my RAA training. It was covered fairly thoroughly in PPL.

 

One of the problems in RAA might be that the results of the weight calculations might be embarrassing, at least for the older lighter aircraft (and even 2 seat GA aircraft like the C150/C152). I suspect there has been a lot of training performed overweight over the years. In GA you probably start learning weight and balance when you start doing navs, when you probably also switch to 4 seat aircraft where the weight isn't a problem.

 

 

90 knots seems like an unlikely number for best rate of climb??

90kt in a 80hp europa mono will normally be looking at 1600fpm sustained climb out... Go-around on this particular day had us just under 300fpm off the deck; and it probably could of been more but with the CG on the forward limit wasn't going to pull the stick back to near stall position to find out or try for VX at 65; thing sinks like a brick once the flaps are retracted... so incremental staged  retraction was required and 90kt level ahead was the safest quickest way to reach a safe altitude on this occasion. Had i been one of those others that brushes aside W&B and the pax weighed 100kg instead of 75kg we would of been into the ground, on the news, or both.

 

And AUW is not always where things go wrong... if i'm lining up to fly solo with too low fuel reserves at the end of the flight then the CG is going past the forward limit; hence the 10-20kg pack strapped in at the luggage station during preflight depending on other factors. Having the battery up front with the engine doesn't help things any.

Edited May 23, 2023 by Area-51

[Thruster88]

1 hour ago, old man emu said:

Honestly, with access to the several graphs present in a POH, there is no need to have even a modicum of arithmetic ability. Just follow the instructions in the POH.

 

 

Here is Page 6 of the POH from, admittedly, a factory manufactured aeroplane.  Start at the left hand axis (weight of object). Move from left to right until you hit the relevant line, then go vertically down to the bottom axis to get the necessary number.

 

 

Once you have all those numbers you add the wieghts to find the total load. Then you add the Moments to get the load Moments. You have to also obtain the aircraft's weight and moment from the handbook that is specific for the aircraft you are using, not generic. From this page, I would use the AOW which doesn't require you to accurately measure the amount of oil in the engine. Just check that it is to the "FULL" mark on the dipstick.

 

 

Once you have done those additions you go to the W&B envelope chart. Again, start at the left hand axis from the total weight and go across to the right. Go up from the bottom (index units) until you intersect the weight line. If the intersection is within the bordered area, you are OK. The area of the Normal Category on the graph includes the Utility Category, which is a restricted W&B combination that allows for more strenuous forcing of the airframe.  It is probably possible for the W&B  for a slim pilot doing a few circuits with, say, 1/4 tanks  to have the in the utility category area, but that's OK for the task of shooting a few circuits.

 

Here's something to think about. If your bladder can take it, and you decide to fly until you've only got your 45 minutes' reserve left in the tanks when you land, it might be possible that the W&B is outside the envelope. Who calculated W&B at the end of a flight?

 

That POH looks like the Australianized (and more shit) version of what the manufacturer would have provided. When I bought my Beech23 in 1996 it came with the legal "Australian" POH and the beautiful manufacturer POH. Some time later.... we were able to APPLY to casa to use the manufacturer version of the POH. I kid you not.

 

Weight and balance. Upon acquiring my trusty Beech23 in '96 I did all the possible weight and balance scenarios as others above have mentioned.  Max 140lb in the baggage and just skinny me with full and low fuel, no problem. Load from the front and don't exceed to 400kg useful load no problem. I have not done a weight and balance since then. Know your aircraft.