Many might remember the Blockbuster movie last year, "Sully", which recreated the "Miracle on the Hudson", on January 15th, 2009. A US Airways Airbus was performing flight US-Air 1549 from New York La Guardia, NY to Charlotte, NC with 150 passengers and 5 crew, performed a controlled emergency landing into the Hudson River after losing both engine power shortly after takeoff from New York's La Guardia Airport. The airplane had reached an altitude of about 2200 feet when both engines were destroyed by a flock of birds and reached a maximum altitude of 3400 feet a few seconds later, before it began to fall to earth.

Flight 1549 was flown by Captain Chesley B. Sullenberger III (58)(Sully) with a total of 19,663 flight hours and First Officer Jeffrey B. Skiles (49) with a total of 15,643 flight hours. All people on board got out of the airplane. 78 people received injuries and were treated by paramedics, most of them minor injuries. One man suffered broken legs, a number of people had to be treated for hypothermia. Several ships and ferries helped to collect the people which got out to the wings and slides, which served life rafts. The media deemed this incident, "The Miracle on the Hudson" and was heard around the world.

    On Saturday, July 23rd, 1983 Air Canada Flight 143 from Montreal to Edmonton was flying at 41,000 feet in a very new Boeing 767 (with only a total of 150 hours in service) began having warning lights and buzzers from the left engine fuel pumps. With over 700 miles left to Edmonton but only 120 miles from Winnipeg, Captain Robert Pearson,(48 with over 15,000 hours flying time) contacted Winnipeg for an emergency landing. As he was descending from 41,000 feet the left engine flamed out. At 26,000 feet, a catastrophic failure occurred, as the right engine also flamed out. The plane was out of fuel and was still 75 miles to Winnipeg.

    First officer, Maurice Quintal , radioed Winnipeg control tower: "Air Canada 143 just lost both engines."

In retrospect, Ground Controller Jessie Widner, thought at the time         "Holy Cow, I'm talking to a dead Man!"

For the next 19 minutes the plane was falling to earth at 2500 feet per minute with 69 soles on board, 63 passengers and 6 flight crew. The story is recreated by a popular television series called: "Mayday, Mayday: Air Disaster"      This recreation of the actual events with comments by the actual crew telling their story was Season 1 of 15, Episode 2: The Gimli Glider in 2002. Recently this series has been seen in the United States over the Smithsonian Channel.

    This presentation will show many video clips from Episode 2 and explain why the plane ran out of fuel.

    This presentation will close describing the miscommunication and transferred into a "story" measurement problem for students to solve via "Unit Conversion", Dimensional Analysis, or "Factor Label" method of problem solving, usually taught in physical science courses, such as chemistry.

    Several handouts will be available for the audience
   The Complete Abstract           True Story Word Problem - No Solution             Link to Dimensional Analysis Web Site (Prob#10)
   Damn Interesting Story            True Story - The Word Problem with Solution
                                                  Link to Setup & Solution to Word Problems
   Sideslip Maneuver                   Dimensional Analysis Problem on Web Site with Step by Step Solution
   Boeing 767 Measuring Sticks
   1997 Soaring Magazine Article: The Gimli Glider
   Questions & Answers About the Boeing 767 Plus Fuel Tank Specifications

    Link to Wikipedia: The Gimli Glider

    Link to Code770: Air Canada 143 - Accident Case Study

   Link to Sylvia Wrigley's "Fear of Flying-The Art of Not Hitting the Ground Too Hard" - The Gimli Glider

   Pilot Recall Heroic Landing: Article Canadian National Post

The Boeing 767 Fuel Tanks

The Boeing 767 Known as the Gimli Glider "

The True Story-The Gimli Glider

      What Happened?     Why did the plane run out of fuel?     How could this happen?

At the time of the incident, Canada was converting to the metric system. As part of this process, the new 767 being acquired by Air Canada were the first to be calibrated for metric units (liters and kilograms) instead of Imperial units (gallons and pounds). All other aircraft were still operating with Imperial units

Like all Boeing 767s, the new plane had a sophisticated computerized fuel gauges, but they were not working properly. However, the plane was still allowed to fly, because there is an alternate method for determining fuel. The Mechanics use dip sticks (float-sticks) located under each of the fuel tanks. The third tank located in the belly of the plan is never used, except for extremely long distance, such as transcontinental flights. The dip sticks are calibrated in centimeters and translated into volume in liters. The Mechanics calculated the three tanks had a total of 7682 Liters of fuel at Montreal. The ground crew convert the depth of fuel shown on the three sticks measured in centimeters and converted to liters using a chart located on the truck.

The fuel truck dispense fuel in volume, usually gallons. Pilots always calculate fuel quantities in mass, because they need to know the total mass of the plane before takeoff. Air Canada pilots had always calculated the mass in pounds, but the new 767 fuel consumption was given in kilograms. This involved using the fuel's density to convert 7682 L to a mass in kilograms, so that the pilot could calculate the mass of fuel that had to be added.

The First Officer of the plane asked the Mechanic for the conversion factor to calculate volume-to-mass conversion, and the Mechanic replied "1.77". But the mechanic just said 1.77. Using that number, the officer and the Mechanic calculated that 4917 L of fuel should be added. The required amount for the trip was 22,300 kg of fuel. The mechanic never gave the First Officer the conversion units which was for pounds per liter, not kg/liter as the First Officer assumed. On examination of the fuel records at Montreal, the group used the density of fuel 1.77 lbs/liter and also used the density of fuel (which varies with temperature) 0.803 kg per liter.

In Science NEVER state a number without stating the unit(s) !

Everyone in Canada at the time was not familiar with the metric system. If they had used Dimensional Analysis, by cancelling units to change one unit to another, this mistake should not have happened. When doing math with unfamiliar units, Dimensional Analysis results in no miscalculation.

For Dimensional Analysis or Unit Conversion or Factor Label method of Problem solving go to:
http://www.lsua.info/chem1001/dimanalysis/unitanalysisIntro.htm
On this web site is Problem #10 about the miscalculation of the Gimli Glider.

The calculation that they actually performed was:
7,682 liters X 1.77 = 13,597 'kg' (error-should have been pounds)
22,300 kg - 13,597 'kg' = 8,703 kg
8,703 kg divided by 1.77 = 4,917 liters

 Another Major Metric/Imperial System Error - Cost $125 million in 1999

The Mars Climate Orbiter 1999

The Mars Orbiter Crash

Launch and trajectory
   The Mars Climate Orbiter probe was launched on December 11, 1998 at 18:45:51 UTC by the National Aeronautics and Space Administration from Space Launch Complex 17A at the Cape Canaveral Air Force Station in Florida, aboard a Delta II 7425 launch vehicle.
   The complete burn sequence lasted 42 minutes bringing the spacecraft into a Hohmann transfer orbit, sending the probe into a 9.5 months, 669 million kilometer trajectory.
   At launch, Mars Climate Orbiter weighed 638 kilograms (1,418 pounds) including propellant.

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    The primary cause of this discrepancy was that one piece of ground software supplied by Lockheed Martin produced results in a United States customary (Imperial) unit (pound-force seconds), contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units (Newton seconds), in accordance with the SIS. Specifically, software that calculated the total impulse produced by thruster firings produced results in pound-force seconds. The trajectory calculation software then used these results - expected to be in newton seconds - to update the predicted position of the spacecraft.