Geronimo4497

Nice to know you're still around, 'bug.

JohnBurke

Previously reported, no changes.

captjns

Been there during my B727 cargo days, done that, and a few T-shirts. Some 19 years ago, there was an isolated case where it was determined a supervisor at a foreign out station accepted bribes, to put extra cargo on the jet massaging weights on the manifests for customs purposes. Fortunately the departure was from a sea level airport with lots of runway. I pulled out the P&PM once level at altitude, I determined estimated actual gross weight based target power settings. Adjusted Ref speeds accordingly. I had all cargo removed and weighed. Voila. Would have been more exiting if departing MMTO.

TiredSoul

According to the article the software generated weights different from actual by 20-30,000lbs.
Thats a 12-15% error in calculated TOW and quite a bit more if it was ZFW.
Isn’t there supposed to be a double-check in the system somewhere?

captjns

The old fashioned way flying pax… Number of Pax times average weights… Bags based on Pax count. Compare the numbers to the load manifest.

TiredSoul

Yeah like a gross error check…something at least.

JohnBurke

Well, garbage-in, garbage-out, but there are several layers of reasonableness checks. Does the weight reported match what's expected? How does it compare to the flight release? Any discrepancies of significance in the basic operating weight, takeoff weight, zero fuel weight? On takeoff, how does the airplane feel? Acceleration? How far down the runway? It's not just about numbers; we get paid for judgement (we pay for bad judgement). If the stop margin is so minimal that we feel we have to pull the airplane off the ground and pass through the tailstrike deck angle to do it, perhaps we need to be requesting a longer runway, if available. A quick check on a cell phone calculator against the numbers with a bow, fuel, and passengers/cargo should give us a value that won't be far off from the finished product. Not required, but it takes seconds and it's a bit of peace of mind. How often do we see big errors? Not often. How many times does it need to happen to bite us in the butt? Once.

I spent a lot of years carrying retardant off runways in airplanes with no performance programs, and minimal numbers, many of them 50+ years old. Very much a tribal knowledge and feel show there. Not that we load and go an airplane full of people (or cargo) based on a how-does-it-feel game, but we shouldn't discount that element of our own skillset either. There are more ways to detect an error than one. It behooves us to use them all, because it takes a really long time to pay off a tailstrike at sixty-nine dollars a paycheck.

I showed for a freight flight, with the airplane having just arrived from an oceanic leg. It was a long leg, and nobody wrote up or reported a problem on the prior leg. Our numbers worked, after a couple of hiccups; and all necessary work done, we departed. It was only once airborne that a mechanic remarked that the last crew complained they'd landed on the nosewheel, hard, and that the airplane had been using a lot of nose-up trim, and felt very nose-heavy. We had no obvious issues at that moment and continued the flight, but we pulled the trip envelope and looked at the last flight numbers. It didn't take long to find that they'd been in error by over 60,000 lbs and when I examined their weight and balance, what was in the trip envelope showed numerous pallets missing (7,000 lbs here and there adds up).

Our numbers added up. We'd had a discrepancy in the takeoff trim values and some takeoff numbers, but resolved them prior to departure, all with valid, verifiable explanations and data, and the airplane flew as it should. The only changes to the airplane from when the other crew got out and we got in was the crew, and the fuel load. Same cargo, and I could clearly see the pallet positions full, through the 9g net. The prior crew did their calculations based on numerous pallets not being in place, and nobody actually looked at the main cargo deck and said, "that doesn't look right." In the end, after a little bit of putting two and two together, the problem stemmed from a loadmaster training a new loadmaster, and using the wrong paperwork, which is what ended up in the trip envelope. A review of the prior flights notations and fuel burns over various waypoints showed nothing amiss, and they landed with the fuel they should have, and their RVSM checks showed them using the same altitudes as planned, but their numbers that were calculated for takeoff, and their CG as they thought it to be, were far off from where it should have been...nobody said a word about that, or their landing, and no explanation was given (subsequent at our destination inspection revealed no damage, airplane flew fine).

Anyone that's ever done mothers day flower flights out of Colombia knows that what's on the weight paperwork, and what's on board, have a very different feel; an entire airplane full of flowers that are weighed dry, then watered before being loaded, has a weight that's a LOT heavier than reported. Back in the day, cargo out of Hong Kong was often much heavier than reported. I've removed the entire load there and had it weighed, and found significant discrepancies. Anyone that's done much cargo in heavy airplanes has an intimate relationship with the red lights at the far end. Anyone that's flown tankers knows that climb is sometimes measured in values less than 100 fpm, and has used hillsides and ridge lift to climb on the way to a fire. That's heavy, no matter how big the airplane. Again, nature of the beast.

What one cannot do is horse the airplane off the ground at all costs. If it's not accelerating properly, take note. If it's not coming off the ground beyond minimum unstick, and rotation has been accomplished per the planning, then something may be wrong. Don't make it worse. Two wrongs, and all that.

I do the same thing with fuel when it comes to personal checks. Our calculations crunch all the numbers, but I also look at the fuel remaining on the last flight, and fuel received, calculate what we should have, compared to what the airplane says we have and what the flight plan says we have. It takes just a few seconds, but they're important seconds. Double check. I have seen fuel that I ordered, put into another airplane, with the fuel receipt delivered to me showing it on my airplane. I've had too much fuel put on my airplane, when someone else ordered fuel and I got it. It does happen, and though not often, quick reasonableness checks or number crunches to ensure that the official data is reasonable, is worth the extra moments.

Likewise, if the performance data shows speeds that don't seem reasonable for what we expect to see at a given weight, then question it. If something doesn't look right, even if the reason isn't immediately clear, then there' s a high probability that it's not right.

rickair7777

My understanding is that with the software glitch (third party vendor) all the data that needed to match procedurally in the cockpit, matched up.

There might have been an opportunity to notice an inconsistency between total pax and the ballpark range of GTOW, but even that can vary 20-30klbs depending on length of flight and therefore fuel load so it wouldn't necessarily jump out at you.