# Kind of similar to climate change



## Woodchuck (Nov 1, 2012)

Back in the day, I worked in a plant that built a 4 solenoid hydraulic valve....I came into work one day and saw dozens of people laying sheets of emery cloth on steel plates, and sanding the valve housing mounting surfaces on them....

I saw disaster in the making, and asked what the problem was...A supervisor told me the layout department had found the mounting surfaces to be .032" out on flatness.....I picked up a housing, and checked it using a 6" scale as a straight edge....It looked good to me....

I took a few housings to the metrology lab, and set them up on a granite surface plate.....Using a leveling fixture, I mounted an interapid dial indicator up on a height gage, leveled the housing, and swept it for flatness...It was flat within .003"....Well within spec. I hunted up a machining consultant we had on contract, took him to the lab, and had him repeat the same procedure I went through.... His results...flat within .003"....

We found the plant manager, explained our findings, and asked him if he was aware of the situation....He called in the quality engineer, and the manufacturing manager, and we again presented our case.....They looked at the computer printout of the original part they had called defective, put their heads together, and concluded.......*WE CHOOSE TO ACCEPT THE PRINTOUT, BECAUSE THE CD-ORDINATE MEASURING MACHINE IS DIGITAL!!!!!
*
I then took the printout to the CMM operator, and had him check another housing.....The new printout said flat within .003"....

Re checking his printout he said OOPS...The CMM had failed to register one of the initial 3 leveling points......Instead of flatness, they were only checking the runout on the holding fixture...

WE *CHOOSE* TO ACCEPT THE PRINTOUT, BECAUSE THE CD-ORDINATE MEASURING MACHINE IS *DIGITAL*

It was digital, but totally wrong...

And they are gambling civilization as we know it on a climate change computer model....rather than just crunching real numbers .....*BECAUSE IT'S DIGITAL.*


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## richardsharpe (Jul 8, 2014)

Good evening
IMHO it has nothing to do with digital or analog, and everything to do with whether the person using the equipment knows what they are doing. The more complex the equipment (like a CMM) the easier it is to make subtle mistakes.

(I'm remember finding a problem with a laser interferometer distance measurement system by using a steel tape measure).


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## Cletus (Apr 27, 2012)

richardsharpe said:


> Good evening
> IMHO it has nothing to do with digital or analog, and everything to do with whether the person using the equipment knows what they are doing. The more complex the equipment (like a CMM) the easier it is to make subtle mistakes.
> 
> (I'm remember finding a problem with a laser interferometer distance measurement system by using a steel tape measure).


Even when you do know how to use the equipment, there will still be some know-it-all jackass backseat driver in the room trying to tell you how to do your job.


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## Married but Happy (Aug 13, 2013)

Cletus said:


> Even when you do know how to use the equipment, there will still be some know-it-all jackass backseat driver in the room trying to tell you how to do your job.


... or some know-it-all jackass backseat driver trying to apply an inappropriate analogy to another situation of totally different character and magnitude. >


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## Thor (Oct 31, 2011)

I run into this frequently with young pilots. They never used the old analog navigation equipment because they learned on GPS and flat screen ****pits. Digital is great when it works, but it also insulates you from the real world. You can lose the ability to use your own eyes on the situation to detect when something is going bad or when you are getting bad data.

Korean Air 007 is a perfect example. They just followed the digital box into Russian airspace where they were shot down. Had they used the old fashioned analog systems to back it up, or run the radar in ground map mode (a form of analog navigation) they would have known they were getting off course.


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## Cletus (Apr 27, 2012)

Married but Happy said:


> ... or some know-it-all jackass backseat driver trying to apply an inappropriate analogy to another situation of totally different character and magnitude. >


Sure, if you're going to take a subtle implication and beat someone over the head with it.


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## richardsharpe (Jul 8, 2014)

Good evening
digital navigation and autopilots are on average safer - but modern pilots often don't really know how to fly. The Asiana crash at SFO in clear weather is a great example - or the horrifying AF 447....






Thor said:


> I run into this frequently with young pilots. They never used the old analog navigation equipment because they learned on GPS and flat screen ****pits. Digital is great when it works, but it also insulates you from the real world. You can lose the ability to use your own eyes on the situation to detect when something is going bad or when you are getting bad data.
> 
> Korean Air 007 is a perfect example. They just followed the digital box into Russian airspace where they were shot down. Had they used the old fashioned analog systems to back it up, or run the radar in ground map mode (a form of analog navigation) they would have known they were getting off course.


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## Thor (Oct 31, 2011)

richardsharpe said:


> Good evening
> digital navigation and autopilots are on average safer - but modern pilots often don't really know how to fly. The Asiana crash at SFO in clear weather is a great example - or the horrifying AF 447....


And then the military imposes a GPS outage for some kind of exercise or test. Now you're back to green needles and analog nav. Or the GPS doesn't have RAIM at your destination, so you can't use it for the non-precision approach. Now you're flying an approach on green needles. Or the FMS craps out and you spend the day flying green needles. Maybe even green needles with no autopilot, below RVSM airspace, with a CATII approach at the end. BTDT. Or a green needles LOC Backcourse approach into Reno, NV. Quick, do you dial in the front course or the back course into the display?

We used to fly into a few places with only an NDB approach, like Sun Valley and others. I'd get new pilots (I was a training captain) out on the line who had never ever in their life flown an NDB approach because they'd never flown an airplane with an ADF! And here we are flying an approach in the snow into a mountain airport.

I look at is as being akin to electronic calculators. They're handy and very helpful as long as the battery works. But if the battery fails, one is dead in the water if they don't know how to do math using pencil and paper.


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## Woodchuck (Nov 1, 2012)

In my case, we had a very good layout technician, and 3 people in upper management that did not have a clue....

*YOU DO NOT CHOOSE WHICH INSTRUMENT TO BELIEVE, YOU CHECK IT BOTH WAYS YOURSELF....

*I might add, at that point in time we also had a quality engineer with a masters in "total quality management" that I WATCHED measuring parts by laying them on the copy machine, running a copy, and measuring the copy....

And an engineer with a masters in metallurgy, that had to be told by line operators when fasteners had hydrogen embrittlement.

Digital measuring machines came on line in the mid 1970's, before that, dial indicators had produced precision measurements since the 1890's, and are still used on a daily basis....for dimensions accurate to 0.0001" they are quick and accurate....

For every wrong reading I have seen from an analog instrument, I have seen 10 from digital devices....Usually the operator forgets to zero the digital device....

I personally have used digital instruments in my tooling and test equipment since the 1980's...I have nothing against them, but if I had 1 shot to check something to .0001", I would grab an analog device...

If I looked out, and saw ocean, I would not land the plane, even if the GPS said I was on the approach to Denver international....


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## richardsharpe (Jul 8, 2014)

Good evening
nothing like getting a DME arc for real for the first time in years, shooting an approach to minimums to get your heart going....

I thought the military had agreed to not activate SA because of too many critical uses of GPS. Still, knowing how to use the needles is really valuable. 





Thor said:


> And then the military imposes a GPS outage for some kind of exercise or test. Now you're back to green needles and analog nav. Or the GPS doesn't have RAIM at your destination, so you can't use it for the non-precision approach. Now you're flying an approach on green needles. Or the FMS craps out and you spend the day flying green needles. Maybe even green needles with no autopilot, below RVSM airspace, with a CATII approach at the end. BTDT. Or a green needles LOC Backcourse approach into Reno, NV. Quick, do you dial in the front course or the back course into the display?
> 
> We used to fly into a few places with only an NDB approach, like Sun Valley and others. I'd get new pilots (I was a training captain) out on the line who had never ever in their life flown an NDB approach because they'd never flown an airplane with an ADF! And here we are flying an approach in the snow into a mountain airport.
> 
> I look at is as being akin to electronic calculators. They're handy and very helpful as long as the battery works. But if the battery fails, one is dead in the water if they don't know how to do math using pencil and paper.


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## Thor (Oct 31, 2011)

richardsharpe said:


> Good evening
> nothing like getting a DME arc for real for the first time in years, shooting an approach to minimums to get your heart going....
> 
> I thought the military had agreed to not activate SA because of too many critical uses of GPS. Still, knowing how to use the needles is really valuable.


Before GPS was allowed in our airliners (FAA was worried we would be less safe with GPS than raw data...) we flew a lot of DME arcs, NDB approaches, and all kinds of odd procedures. At the speeds we fly it is a whole different thing than in a piston powered airplane. There's no time for the usual cross checks and corrections. But it works.

We've had a few GPS outages in the west here. Dugway seems to be involved at times, as are some of the Nevada ranges. It's been maybe 18 months or so since the last time I had to deal with one.


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## richardsharpe (Jul 8, 2014)

Good evening
Do airliners have inav? Is the fall back with no GPS old VORs etc?
Do they have glonass receivers yet




Thor said:


> Before GPS was allowed in our airliners (FAA was worried we would be less safe with GPS than raw data...) we flew a lot of DME arcs, NDB approaches, and all kinds of odd procedures. At the speeds we fly it is a whole different thing than in a piston powered airplane. There's no time for the usual cross checks and corrections. But it works.
> 
> We've had a few GPS outages in the west here. Dugway seems to be involved at times, as are some of the Nevada ranges. It's been maybe 18 months or so since the last time I had to deal with one.


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## Thor (Oct 31, 2011)

richardsharpe said:


> Good evening
> Do airliners have inav? Is the fall back with no GPS old VORs etc?
> Do they have glonass receivers yet


Our FMS utilizes VOR, DME, and GPS. There are a few inertial nav airplanes in the fleet, which provide data to the FMS. Under normal operations we don't know what each input is saying because the FMS just generates the moving map display and drives the white needles for nav. The box auto-tunes the VORs and DMEs and constantly is checking position from every navaid it can find. If there is a discrepancy or failure we get notified, and can manually disable a nav input if the system doesn't do it for us.

GPS is considered primary by the FMS, so a wonky GPS will still be considered the most valid position and the other inputs will be flagged as incorrect until we disable GPS.

For green needles we can go to raw data VOR, DME, and NDB.

I doubt we'd ever get GLONASS for two reasons. One is it is controlled outside of the ability of the FAA to monitor or evaluate. So they won't be willing to let us use it. Second, being a Russian system I doubt the US government would want to endorse it.


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## tech-novelist (May 15, 2014)

Thor said:


> And then the military imposes a GPS outage for some kind of exercise or test. Now you're back to green needles and analog nav. Or the GPS doesn't have RAIM at your destination, so you can't use it for the non-precision approach. Now you're flying an approach on green needles. Or the FMS craps out and you spend the day flying green needles. Maybe even green needles with no autopilot, below RVSM airspace, with a CATII approach at the end. BTDT. Or a green needles LOC Backcourse approach into Reno, NV. Quick, do you dial in the front course or the back course into the display?
> 
> We used to fly into a few places with only an NDB approach, like Sun Valley and others. I'd get new pilots (I was a training captain) out on the line who had never ever in their life flown an NDB approach because they'd never flown an airplane with an ADF! And here we are flying an approach in the snow into a mountain airport.
> 
> I look at is as being akin to electronic calculators. They're handy and very helpful as long as the battery works. But if the battery fails, one is dead in the water if they don't know how to do math using pencil and paper.


I assume from this that you are (or were) an airline pilot. Is that right?


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## Thor (Oct 31, 2011)

technovelist said:


> I assume from this that you are (or were) an airline pilot. Is that right?


Yes, current airline captain.


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## tech-novelist (May 15, 2014)

Thor said:


> Yes, current airline captain.


I'm glad you have the experience to deal with the unexpected, since of course that job has one of the heaviest burdens of responsibility.

BTW, I have met Captain Haynes of the Sioux City crash and heard his story first-hand. That was a pretty intense situation, and it's amazing that anyone survived!


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## Thor (Oct 31, 2011)

I am still amazed that they got the airplane anywhere near an airport at all. Really a remarkable feat.


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## richardsharpe (Jul 8, 2014)

Good evening
How on earth do long haul airline pilots deal with jet lag. I have to wait a week after an international trip until I'm safe to fly again. Add mild hypoxia from the cabin altitude and I'm amazed planes aren't dropping out of the sky.


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## Thor (Oct 31, 2011)

I don't do long haul, just USA, Canada, and Mexico. Our schedules get all jacked around, working early mornings some days, late nights others.

The best way I've found to deal with jet lag is to mentally accept the new local time as being "real". I try to not mentally convert the local time back to home time, especially when I go east and then have to get up early east coast time.

Caffeine is actually an enemy if you drink it regularly. If you don't drink caffeine you can use a small cup of coffee in the morning to reset your body clock. This is effective when going east.

The alternate method is to stay on your home time schedule. This wouldn't work if you have work to the new local time zone, but if your schedule allows it, just don't try to switch to the new time zone at all.


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