Thursday, January 9, 2014

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?

Friday, January 3, 2014


Readers know that I am a big believer in habits.  When you're on fire your habits will take over; you're unlikely to invent a new technique.

No, this is not about New Year's Resolutions.

My first flight of 2014 was a paid maintenance flight.  Salt Lake City (KSLC) was really low IFR, pushing Category II minimums.  Good thing I wasn't going there.  Or was I?

As I departed home I saw a landing light coming down the airway from KSLC and sure enough pretty soon the Tower was talking to a SkyWest flight that had diverted after a long hold at KSLC.

Radar coverage is sparse in this area so Flight Following is generally unavailable; still I decided to at least listen to Center (the habit).  I heard a lot of non-standard phraseology:

"Climb and maintain Flight Level 290, I have to keep you below the holding stack."

"Are they missing [the approach] in Salt Lake?"

"What's the Salt Lake RVR?" [The answer was "I'll check" then "1,000 feet, but it looks like it's going down."

"Can we just circle visually?"

My destination, Twin Falls (KTWF) is one of the few non-radar approach control facilities in the USA.  I usually call Approach (that's the habit) and they usually don't care, but today the approach controller was juggling two unexpected jets in his head and it seemed wise to let him know that I was coming.  (My groundspeed was 65 knots, I would be coming for a loooong time.)  For the moment both jets were above me but I knew that that would inevitably change, so I stayed north of the runway 26 final approach.

"55J, say distance from Twin Falls please?"  He asked three times.

One jet was on final and the other was on right downwind, metal-to-metal with me.  I made sure my transponder was on so I'd show on the RJ's TCAS.

About 15 miles out I saw the RJ turn base and called "I've got the RJ turning right base in sight."

"Follow that RJ to the airport, contact Tower now on 118.2."

Now the use of the word "follow" might have been correct by the ATC handbook but I was indicating 95 knots with a 40 knot headwind, while the jet was indicating 200 knots with the same headwind.  The jet would be landed and the passengers deplaned before I landed, but I agreed and headed in.

The lesson here is that this was all no big deal, because of my habit.  It's my habit to contact Approach Control, even though 9 times out of 10 they don't care.  It's my habit to set up the radios for an instrument approach, so when the Tower asked for my distance all I had to do was look down at the DME display.