One Million Dollars
In the Austin Powers movies Dr. Evil, hopelessly behind the times, wants to hold the world at ransom for [pause] One Million Dollars. The joke is that that's not much, but for me and probably you that is a very large amount of money. Even for an airline, that is a very large amount of money.
A recent story in Aviation Week and Space Technology caught my eye and reinforces my tendency toward acquiring lots of data and acting rationally.
An unnamed airline was operating a flight from the West Coast of the USA to Europe. (I was once a passenger on a Boeing 747SP from London Heathrow to KLAX; this is a long flight! For me, with clear skies and daylight all the way, it was a spectacular flight, allowing me to see Iceland, Greenland, and Hudson's Bay.) This crew got a "Low Tire Pressure" warning somewhere over the USA.
These days every automobile service center is familiar with these warnings. When the weather gets cold lots of cars get these warnings, by simple physics: a 25 degree Celsius temperature drop from close to standard is, directly, a 10% drop in pressure. So when the temperature drops from summer's 30C to winter's 5C the colder tires really have lower pressure.
Presumably the engineers who design these sensors for aircraft compensate for the expected pressure change of 30% when an airplane leaves 30C KLAX and climbs to the -50C stratosphere. This tire was genuinely leaking.
The airline's maintenance department took several pressure readings at 20 minute intervals to determine the leak rate, and calculated (that's the word I like!) that the tire would be flat on arrival in Europe. This didn't worry them operationally, but someone remembered that every time an airplane landed in Europe with a flat tire it cost the airline $1,000,000.
With this information the dispatchers suggested that the airplane land while still in the USA, while the tire still had air. The crew did so, the tire got fixed, and the passengers were on their way after a small delay. This was probably another complex calculation: find a maintenance base with a tire available that was far enough along so that the airplane was below its maximum landing weight.
The airline saved $1,000,000.
Now one of my mottoes (see the sidebar to the right) is that a pilot should never think about money while in the air, but with an outcome like this I conclude that it was a good decision. So I suppose I need to update my motto?