'Zactly. The key word in @Richard_Pearse’s fine explanation being “significantly”. The same “significantly” qualifier applies when the other pilot is hand-flying. Which is something any CFI is familiar with. The mere fact the other pilot (or the computer) isn’t doing exactly what you’d do (or more realistically think you’d do) at this exact moment doesn’t mean they’re screwing up.
There are tolerances to all this stuff. And except very close to the ground, the tolerances are also in the time dimension. e.g drifting a bit off glideslope is not a crisis at 1000 feet and can be fixed at our (relative) leisure over the next 20 seconds. The same offset at 50 feet is a “Do something right F***ing now this very millisecond!” situation.
All this is a symptom of another old adage of aviation:
Measure it with a micrometer, mark it with a lumber crayon, and cut it with an ax.
Meaning a lot of precision is utterly misplaced in the heat of battle.
We do all these highfalutin calculations about weight, flaps, and wind to establish a target speed. Given approach speeds around 150 knots (737 flies fast), that’s to a precision of ~2/3rds of 1 percent.
Then we make the approach and the wind at any moment is 10% (or 50%) different than ATIS, our actual weight is 2% different, and the most accurately we can hand fly is another couple percent. And the book tolerances on its/our performance is minus 8% / plus 15%.
WASHINGTON, Oct 29 (Reuters) - Boeing (BA.N) overcharged the U.S. Air Force for spare parts for C-17 transport planes, including marking up the price on soap dispensers by 7,943%, according to a report by a Pentagon watchdog.
The Department of Defense Office of Inspector General said on Tuesday the Air Force overpaid nearly $1 million for a dozen spare parts, including $149,072 for an undisclosed number of lavatory soap dispensers from the U.S. planemaker and defense contractor.
The article mentions that only a dozen spare parts were in play. Even assuming the soap dispensers were 11 out of the 12, that means the comparison price was about $170 and the inflated price was over $13k. That seems a little high even for something that meets “military specifications” as claimed by Boeing.
Could be. But $149k/80 =~ $1900. So even if it’s more than a dozen, it’s probably still less than a hundred. Either way, it’s the 80x markup that’s the problem.
Maybe Boeing will claim that it cost $145k just to develop the certification program that the military requested, and that the per-item cost isn’t really that high. It’s just that they didn’t order very many.
I wonder if it requires special $10,000/liter soap that’s liquid at that temperature. The regulation only mentions exposure, not that the device must work at that temperature.
The guidance is actually surprisingly vague on what the “aircraft as a total system” does and does not include. Obviously you do want all your flight controls and computers and fuel pumps and whatnot to start up and operate properly after cold soak. You want seats and seatbelts to function and not freeze/seize. You want oxygen masks to deploy, fire extinguishers to discharge if needed, etc. The idea is that the cold won’t break it. It’s acceptable that you may need particular start up procedures.
It’s debatable - and, literally, it’s an ongoing debate - as to what to do with the water system.
It’s, I suppose, debatable whether the soap is part of that system, but to apply the implications of the standard to a soap dispenser, there are decisions to be made if it needs to be purged before cold soak (if the soap breaks the dispenser lines when it freezes or thaws, where does that leak go?). Or demonstrate the container/lines can tolerate the temperature and perhaps an overpressure or something. I’ve never actually thought it through in depth. But, the dispenser is, in most cases, a tested a certified part and you do pay extra for the paperwork that comes with it.
I have no idea what a reasonable cost is for an aviation soap dispenser, but it’s definitely more than what you can get at Walmart.
I should add that on some planes, like business jets, the problem is solved by treating soap dispensers as carry-on “loose” equipment. It’s like a throw pillow; just get your Walmart dispenser on the counter, shove it in a drawer or whatever, and replace as necessary. Then you just really design galleys and lavatories and floors to handle spills and you’re fine.
In my hypothetical I’m imagining a built-in device with a reservoir that’s intended to be refilled rarely but used often.
Could be! I haven’t flown much recently and offhand, I don’t actually know what the soap dispensers look like in any given commercial plane. I’ve used them but have no recollection of them.
I probably could waste time looking for information at work but I probably won’t. One day I’ll come across data and go a-ha!
The typical modern airplane soap dispenser is a disposable plastic pump bottle with a few floz of thick liquid soap. Just like you might buy at the grocery store.
But designed with a weird base so passengers are disinclined to steal it, since it won’t stand up on its own and is only usable when screwed into the built-in non-stealable base attached to the sink area.
I do not know if the bottles are refilled by cleaning staff from an e.g. gallon jug of soap or are just pitched & replaced when empty. The former is possible, but the latter sounds far more likely, especially on rush-rush mid-day turnarounds. Overnight deep cleans get done weekly-ish and they may do the slower but more cost-effective refills then.
I found this funny – I can imagine there is at lease SOME temptation to do this, though of course professional ethics not to mention getting fired/in trouble with FAA stops pilots from doing so
Makes a lot more sense than a built-in certified device! I just got amused at the hypothetical and then ran with it.
I enjoy musing about how/if absurd stuff could be certified. Recent silly discussions have involved disco balls and mounted antlers. A hot tub would be… impractical…but it probably could be accomplished. Easier to do on a bigger plane. Purge before cold soak!
Emirates has actual showers in First Class on their A380s (and it wouldn’t surprise me if some private jets had them too). Now I have to wonder how exactly they got them certified.
Running water is running water. A shower is just a larger sink with a higher flow rate faucet & a larger drain. If you can certificate the small version, you also know how you can certificate the larger version.
Makes sense. Although the shower also includes a seat with a seatbelt so the occupant can strap in during turbulence. But I’m sure aerospace companies already know how to certify seats as well.
The existing rules don’t really take such things into account, but there are ways to negotiate these novel designs with the regulatory agencies and get them certified. These things are generally public information but involve defining injury protection means and allowed loads on crash test dummies. Can take a couple years to do from idea to cert.
Some business jets do indeed have showers, particularly the long range stuff. Not much need on short flights.
