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Politics : The Environmentalist Thread -- Ignore unavailable to you. Want to Upgrade?

To: neolib who wrote (19930)	1/31/2008 12:55:22 AM
From: maceng2	Read Replies (2) \| Respond to of 36918

As a kid, due to compulsory metric conversion, my age group grew up converting from imperial to metric and back again. metric.org.uk First there was the currency conversion from £/s/d to £/p. That is 12 old pence to the shilling, and 20 shillings to the UK pound (money not weight -g-). The older folks at the time had many problems with conversion, and it was an opportunity for retailers to hike prices which was done across the board. There was an uproar, but thats just life I guess. The main problem with anything metric is getting the decimal point in the right place. Mistakes tend to be out by a factor of ten or more. I have always done rough calculations by several methods just for that reason. If my rough calculation comes up with a similar answer within an order of magnitude, I know it may be right. At sea, when the admiralty charts converted depths from fathoms (six feet) to meters, there were ships running aground all over the place for years. Many old imperial units were handy for a number of reasons and I always liked fathoms as I'm 5 feet 11 7/8" inches tall. -g- A fathom is a natural unit. Most people in the UK still price petrol (Gas) in UK pounds per UK gallon, (not to be confused with the USA gallon) not litres. We will always use miles instead of kilometers to measure distance on the roads I think. The big problem with metric conversion is when industry converted. The building trades became a nightmare for example. Take plaster board (sheet rock as the Americans call it), every business had to multiply all stock items by three. There were the old imperial sizes (in inches), imperial metric (cut to mm but very slightly different in size usually), then the final official metric size. Consider every blessed item used in the construction trade. Every pipe, cable, wire tie.... EVERYTHING in three slightly different sizes. The metric conversion caused havoc and cost billions in screw ups when the country could least afford it. Many of the imperial sizes, the standard house brick for example, were very useful sizes indeed. In physics though, not using SI units would be almost unthinkable now. Wouldn't even bother. Converting the final answer to any other units is easy, just look at the conversion table and do the multiplication. How can anybody can use anything but SI units for space flight calculations boggles my imagination. I guess you could get used to it, but I personally would not touch anything other then SI units for kinetic energy calculations. Chemical reactions in imperial units? I don't think so -g-.

To: neolib who wrote (19930)	1/31/2008 10:04:07 AM
From: Alastair McIntosh	Read Replies (1) \| Respond to of 36918

In 1983 an Air Canada Boeing 767 ran out of fuel and became a glider. en.wikipedia.org At the time of the incident, Canada was converting to the metric system. As part of this process, the new 767s being acquired by Air Canada were the first to be calibrated for the new system, using litres and kilograms instead of gallons and pounds. All other aircraft were still operating with English measurements. For the trip to Edmonton, the pilot calculated a fuel requirement of 22,300 kg. A dripstick check indicated that there were 7,682 litres already in the tanks. In order to calculate how much more fuel had to be uplifted the crew needed to convert the quantity in the tanks to a weight, subtract that figure from 22,300 and convert the result back into a quantity. (This task had previously been completed by the Flight Engineer, but the 767 was the first of a new generation of airliners operated by two flight crew and the Flight Engineer position had been made redundant.) A litre of jet fuel weighs 0.803 kg, so the correct calculation was: 7682 litres x 0.803 = 6169 kg 22300 kg – 6169 kg = 16131 kg 16131 kg ÷ 0.803 = 20163 litres Between the ground crew and flight crew, however, they arrived at an incorrect conversion factor of 1.77, the weight of a litre of fuel in pounds. This was the conversion factor provided on the refueller’s paperwork and which had always been used for the rest of the airline’s imperial calibrated fleet. Their calculation produced: 7682 litres x 1.77 = 13597 ‘kg’ 22300 kg – 13597 ‘kg’ = 8703 kg 8703 kg ÷ 1.77 = 4916 litres Instead of 22,300 kg of fuel, they had 22,300 pounds on board — only a little over 10,000 kg, or less than half the amount required to reach their destination. Knowing the problems with the FQIS, the Captain double-checked their calculations but was given the same incorrect conversion factor. All he did was check their arithmetic, inevitably coming up with the same figures.