What's in a "foot"? (Surveying)

[turnkey4099]

Confusion between the metric system and English system nearly killed me and the 240 people seated behind me.

Very early, one dark and stormy morning, after flying our DC-10 (tired) across the Atlantic to Copenhagen, the flight engineer (second officer) handed us the ATIS (Automatic Terminal Information Service) information......... with the WRONG altimeter setting shown.
He had copied the setting in inches of mercury, when it should have been in millibars (now called - Hpa - Hectopascals).
We (co-pilot and I) set our altimeters to inches of mercury, as the info sheet showed.
Co-pilot was flying (his turn), and I was watching for the runway.
We broke out of the clouds when both our altimeters read about 1100 ft.
I saw the water come into view immediately, perhaps about 300 ft. below the A/C.
We were 800 ft. too low, and several miles out from the runway ( VOR/DME)
Had the clouds been even lower, and had we continued down to the legal approach minimum altitude, we would have obviously crashed.
I immediately initiated a go-around, and while wetting our pants on the go-around, we discovered the error.

The flight engineer (we called them second officers) had heard the correct numbers, but had written them out as being inches of mercury instead of millibars (we had been on duty 15 hours, and were all very tired).
This was just one of many incidents that have occurred over the years.
NASA tracks such incidents, and I made a report upon returning to the USA
Many similar incidents have resulted in deaths.

Can you guess which side of the metric/English measurement system issue I am on?
Metric of course!
THAT is how the majority of the aviation world lives!

The then co-pilot and I are both retired.
Before he retired, he was a victim (unhurt) in an India crew hotel terrorist attack.
Twice lucky!

For a real interesting case of confusion of systems, google "Gimli Glider". 747, I think it was, ran out of fuel in Canada because the refueling was done in wrong system. Glided to a dead sstick landing on an old WWII air field.

 

[fried1765]

For a real interesting case of confusion of systems, google "Gimli Glider". 747, I think it was, ran out of fuel in Canada because the refueling was done in wrong system. Glided to a dead sstick landing on an old WWII air field.

"Gimli glider" was a B-767 ,not a B-747.

 

[turnkey4099]

:thumbsup: I'm with you, but it would be so much easier if everyone was in. I also agree with those saying STOP converting! So much simpler to just call it as it is, rather than converting and juggling 2 systems.
Another thought... has anyone measured lumber sheet goods lately? Much of the plywood comes from outside the US, and it's not 3/4" or 1/2". It's either labeled in mm, or with some goofy fraction that can't be matched with any other lumber anyway.

One of the dumbest arguments that I heard was from a mechanic. "I wouldn't be able to tell what size wrench to grab". Why, when you need a 7/16", you grab the 7/16" without evey looking at the stamping. It wouild be the same in metric WITH THE ADDED BENEFIT of having fewer sizes.

 

[Jstpssng]

Maybe I'm wrong, but not joining the rest of the world and changing over to metric can't be good for the long term ability of industry to compete on the global level.

 

[pmsmechanic]

One of the dumbest arguments that I heard was from a mechanic. "I wouldn't be able to tell what size wrench to grab". Why, when you need a 7/16", you grab the 7/16" without evey looking at the stamping. It wouild be the same in metric WITH THE ADDED BENEFIT of having fewer sizes.

Actually metric has more sizes. Sae 3/8' - 3/4" is seven wrenches. Metric 10mm - 19mm is 10 wrenches.

 

[Industrial Toys]

I never have the right wrench anyway. Go back and forth to the drawer half a dozen or more times, searching between imperial and metric, only to find it's probaby a metric size, that my kit, didn't come with. This seems to get worst with larger wrenches over 1".

 

[aczlan]

Actually metric has more sizes. Sae 3/8' - 3/4" is seven wrenches. Metric 10mm - 19mm is 10 wrenches.

And if you want that even more fun, add in the British Wentworth bolts that were popular back in the mid-1900s.
The wrenches and sockets are by bolt diameter rather than by the head size.
As such, a 5/16 wrench is between 1/2" and 9/16" (about 13.3MM IIRC).

Aaron Z

 

[k0ua]

Maybe I'm wrong, but not joining the rest of the world and changing over to metric can't be good for the long term ability of industry to compete on the global level.[/

Whoops, I read your post wrong.

 

[k0ua]

And if you want that even more fun, add in the British Wentworth bolts that were popular back in the mid-1900s.
The wrenches and sockets are by bolt diameter rather than by the head size.
As such, a 5/16 wrench is between 1/2" and 9/16" (about 13.3MM IIRC).

Aaron Z

And we don't need BSP or British Straight Pipe fitting either. But we have them. I have some of the grease zerks on my metric Kioti using them... What ever the he77 for, I don't know.

 

[goeduck]

X/2, X/4, X/8, X/16, X/32 and full inch. Converting which is the next bigger or smaller than which is harder than metric. Maybe not if you pull wrenches every day. The think what saves me is I have holders for sockets and just go up or down one when I get to the drawer. But wrenches get a little more difficult. I lay them in the drawers in order but in a hurry I can put one in the wrong spot.