jerryc41 wrote:
Last night I watched a movie about a 767 that almost crashed because it ran out of fuel. I had also seen the FAA investigation film about the same incident. Nearly one hundred people came close to dying because of errors made in Imperial/metric conversions when fueling the plane. We have been referred to as part of the Axis of Medieval because only Burma and Nigeria join us in shunning the use of the metric system.
We already know about liters and millimeters for cameras and lenses, so why not take the plunge and join the rest of the civilized world? You may recall that the Hubble Space Telescope had a problem because of the metric conversion. We wasted a lot of time and money fixing that problem.
I put the blame squarely on the shoulders of the politicians. They are the ones who would pass the necessary law to switch. Taking a wild guess, I suspect money is behind their decision to keep us isolated from the rest of the world. Mechanics must buy tools in both metric and SAE measurements, for one thing. I once had to replace the bumper on a Buick. Exactly half the bolts were SAE, and half were metric. Does that make sense? These are the same politicians who can't find a way to provide us with health insurance, like all the other developed countries.
Okay, that's my rant for the day.
Last night I watched a movie about a 767 that almo... (
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This is an interesting thread. It was previously mentioned about using English when communication with air traffic control. English is the universal language of aviation. Some other interesting items are that in much of the world, altitudes are referred to in feet and assigned in thousand foot increments to ensure adequate aircraft separation. Then there is knots (nautical miles per hour) versus statute miles per hour. A nautical mile is 1.1508 statute ("ground") miles and is equal to one minute of latitude. Knots are commonly used to indicate airspeeds, as this is useful for navigation. Aircraft indicated airspeed indicators commonly indicated statute miles per hour up until somewhere around the middle of the last century, and now commonly indicate knots. Since most aircraft are "about speed," it took longer for most general aviation ("small") aircraft to switch to knots. When Mooney decided to release a new model many years ago, they called it to 201, because it could go 201 miles per hour (on only 200 HP). Good marketing, as 201 MPH seems faster than 170 knots and the Mooney 170 doesn't sound as good as the Mooney 170.
Another aviation related item is aircraft ceiling, or how high an aircraft can fly. The commonly used reference is service ceiling, which is generally accepted as the altitude at which the climb rate is down to 100 feet/minute. At that rate, it would take 10 minutes to climb another 1,000 feet (to get to a different assigned altitude - see above), so that is the practical limit. In the parts of the world that use SI units, service ceiling is generally defined as when the climb rate reaches 0.5 meters/second, which works out to about 98.5 feet/second. BTW, the absolute ceiling of an aircraft is not a practical measure, as an aircraft will continue to climb as it gets lighter by burning fuel, so the absolute ceiling is reached when the aircraft runs out of fuel.
I tell my aircraft design students that they have to be "mentally ambidextrous" and able use both systems of measurement, though we work most of our problems using English units.
I'm comfortable using both systems. When I got my engineering degree in 1974, the physics and chemistry classes were using mostly SI units, while the aircraft classes used mostly English units. I think mostly in the English system, but that is "situational." Back when I got my first car, a 1960 Mini, it was a real mixture: 850 cc engine (actually 848), 10 inch diameter wheels......... Then I got a new 1967 Barracuda with a 273 cubic inch V-8 that I considered as a 4.5 liter (actually 4,474 cc), because when I went rallying in it I was in the 3.0-4.5 liter class, mostly competing against Jaguar E-Types of 3.8 or 4.2 liters. I build model airplanes and do some woodworking, and most of the wood is in inches and feet, though I fly 2 meter span radio controlled sailplanes made out of wood that comes in either 36" or 48" lengths. There is a mixture used in the hardware.
BTW Jerry, I use the Gimli Glider incident as an example in one of my classes.