Friday, September 30, 2011

Oops in the skies

Each one of us can remember a moment when we pressed the wrong button but how about when this person is a pilot and caused a mid air scare. On September 6 a Japanese co-pilot flying ANA airlines en route from Naha to Tokyo carrying 117 passengers pressed the wrong button while trying to let captain back in from the restroom. Instead of pressing the unlock button for the cockpit door he mistakenly pushed the rudder trim knob. This caused the plane to roll 131.7 degrees to the left leaving it almost belly up. The plane also plunged about 1900 meters from a height of about 12500 meters in a mere 30 seconds as its nose pointed down 35 degrees. Luckily no one was seriously injured as the plane later landed in Tokyo safely. You can read about it more here.

Mid air scare by pilots is nothing new. In 2009 an Air India flight en route from Sharjah to New Delhi had the cockpit unmanned as the captain and co-pilot had a fist fight with two members of the cabin crew. The mid air scuffle happened in clear view of the passengers as the plane flew over Pakistan air. The crew settled after a while as if nothing happened and the plane landed safely with 117 passengers. You can read the whole story here.

Then there was the 2009 case of the two Northwest pilots who overshot the intended destination by more than 150 miles. The plane was flying from San Diego to Minneapolis carrying 144 passengers. The pilots told the investigators later that they were busy with their personal laptops in addition to distractions in the form of bathroom break and chat with flight attendant, all this while the air traffic controllers were frantically trying to reach them for more than an hour and the plane flying on autopilot at 37000 feet. You can read more about it here.

Don't worry as these incidents happen rarely. Remember there are also the brave pilots like Captain Chesley “Sully” Sullenberger, who successfully landed US Airways plane carrying 155 people in the Hudson River after its engines failed.

Monday, September 26, 2011

Bay Area Traffic

Commuting for work in bay area is tough during peak office hours, freeways like 101, 880 can test anybody's patience. I commute to work everyday driving for about 25 miles each way, drive times can range anywhere from 30 minutes to 1 hour depending on the time of day.

I know by personal experience that it did feel a little easy driving in 2008 and 2009 during the peak of subprime mortgage crisis. This would suggest unemployment rate inversely affects the traffic congestion, higher unemployment and less people have a workplace to commute to.

To validate this lets look at the traffic congestion trend for the last 20 years (1990-2009) and the unemployment trend during the same period.

Using the traffic congestion data available at the Urban Mobility Information at Texas Transportation Institute, I plotted two measures - Travel Time Index and Annual Delay per Auto Commuter. Travel Time Index is the ratio of travel time in the peak period to travel time in free-flow. A value of 1.30 indicates a 20-minute free-flow trip takes 26 minutes in the peak. Annual Delay per Auto Commuter is the yearly sum of all the per-trip delays for those persons who travel in the peak period (6 to 10 a.m. and 3 to 7 p.m.). See charts below:

Below is a chart that shows the unemployment rate in the counties of Santa Clara and San Francisco using the data available at California Employee Development Department:

The traffic congestion trend almost inversely followed the unemployment trend. This raises curiosity as to what economic events caused these sharp surges and drops. Saving and loan crisis and the housing bust led to recession of 1990-1991. Coupled with high gas prices due to gulf war the unemployment rose sharply. From 1995 to 2000 we see a drop in unemployment during the dot com bubble. March 2000 marked the dot com bubble burst with a sharp decline in the stock market and high unemployment particularly in technology sector thus impacting bay area. By 2004 economy started to turn around until we saw the subprime mortgage crisis of 2008.