The Paperless Groundhog

The Science of Secrets


Really High, Technology


On January 31st, 2001 A Japan Airlines Boeing 747 cruising at 36,000 feet, near Tokyo, swerved sharply to avoid hitting a JAL DC-10 by just about 30 feet, over the skies of Japan. There were a total of 648 people on the two aircraft. 42 people were hurt in the maneuver. This incident classified as a “near miss”, was indeed a very close call. Closer to home, in November 1996, a Saudi Arabian Jumbo minutes after taking off from New Delhi, collided with a Russian cargo jet, killing 349 people. Prior reported commercial airline collisions occurred in 1992 (Libya) and 1986 (California). While near misses are somewhat “common”, the collisions in involving commercial flights are very rare, even in the face of dramatically rising aircraft operations. Casualties, for any reason, on commercial air transport are at an all time low. The safety record of air travel is unchallenged by any other form of travel. In fact a casual evening stroll down a city street is much more dangerous than a trans-continental flight on a commercial airline. This impeccable record is one of the crowning success stories of technology.


Technology has touched almost every aspect of our existence, ever since the industrial revolution (around 1850) steamed its way into human life. Today, computers provide us with information and communication, telephones (both wired and wireless) connects us in a few seconds to answering machines. Medical Science has produced an array of drugs for millions of problems, and many more are on the horizon. Invasive surgery is being replaced with microsurgery at a rapid pace. Genetic engineering hold amazing yet frightening prospects. In the face of the dazzling variety of technological breakthroughs of the past decade, the grandeur of space exploration almost looks blasé.


The application of technology is not only widespread, its often “taken for granted”, that is we do not even stop to think about the impact. One area where technology has worked wonders to make life smoother has been in the area of transportation. Transportation, at a basic level comprises of air, surface (rail and roads) and water. Every facet of transportation has gone though significant innovations over the past decade. The most visible of these is passenger air transport.


As users of the air transport systems, our first interaction with aviation technology is with the airline reservation system. The airline reservation system is a vast array of computers that track every seat on every flight on practically every airline thought the intricate labyrinth of routes covering the globe. Instant availability of flight data, schedules, fares and reservations are the taken for granted features, of the airline reservation system. Before the advent of the Web, the airline reservation system was accessible only to travel agents. Today, Web interfaces to these systems enable anyone with a computer to peruse schedules, flights actual flight status (in real time) and fares for all airlines (For example, via or Bookings can be made, tickets can be purchased and even ordinary mortals can do seat selection. Once the booking process is over, and you head for the airport, you meet the real monster, the aircraft.


An aircraft is an absolute engineering marvel. From the alloys used to build the skin, to the passenger comfort systems, all the way to the electronics and avionics that interface to the hostile environment and provide a comfortable and safe ride. Jet airplanes fly at 39,000 feet, where the air is devoid of oxygen and temperatures are about –50C. They travel at about 600mph, and encounter remarkably strong forces due to turbulence and air pockets and yet never break apart. The engines produce unthinkable power, or thrust. The speed of an aircraft is not limited as much by technology, but by a natural phenomenon—the speed of sound, which is about 750 mph. The closer an object reaches this magic number, the higher is the force needed to propel it, and the increase is so dramatic, that the cost to fly higher faster than that, though the atmosphere is very prohibitive. Economical transportation that exceeds the speed of sound, is probably never going to be realizable.


The FAA (Federal Aviation Administration) is a US government organization that controls air transport in the US, but its dictates are followed around the world. One of its rules is called ETOPS (Extended Twin Operations). Initially ETOPS dictated that planes with two engines are not allowed to carry passengers on flights that takes them over 1 hour from a closest landing strip. As planes got safer ETOPS limit was extended to 2 hours allowing planes such as the Boeing 767 to ferry passengers across the Atlantic. In the year 2000 the FAA increased ETOPS to 207 minutes for the Boeing 777, making it the first commercial airliner with two engines available for really long-haul flights. Pilots often refer to this rule as “Engines Turn Or Passengers Swim”.


Today the Boeing 777 flies one of the longest commercial routes, particularly on flights from New York to Hong Kong, a distance of 8000 miles. A jet taking off from New York, goes north over Canada across the Hudson Bay, into the Arctic Circle and then southwards over huge tracts of Russia and the right over Beijing to land at Honk Kong, about 15 hours later.


Last month, I was on a flight from Tokyo to Los Angeles a distance of 5500 miles. After the interminable delays on the tarmac the captain announced clearance to takeoff and soon we thundered off at exactly 4:05pm Tokyo time. As usual, the plane went though screaming ascends and weird maneuvers to avoid whatever it could have hit. Eventually as we leveled off at about 20,000 feet the captain’s adrenaline subsided, and he announced that we are on a 9 hour 30 minute flight and he expect to touch ground in Los Angeles at 7:35 am local time. Just for larks, I set my watch to LA time and waited. Sure enough, as the aircraft hit the ground, I looked at the watch. It was 7:40 am.


How did the captain know the time of landing? This seemingly simple thing in actuality is quite complex. While the aircraft is on its way, it will encounter strong winds, other air traffic, unpredictable weather patterns and last but not the least a congested landing pattern at the destination. An oversimplified explanation is as follows. Every major air route is composed of virtual flying boxes, moving from source to destination in real time. Planes are slotted into these boxes even before they take off. Thus even before the place left the gate at Tokyo, it was assigned one of the boxes that would take it to Los Angeles. After it took off, the pilot was instructed to speed up, or slow down till the aircraft entered its box. From that point, its speed was controlled so that it remained in the slot, which eventually touched down in LAX exactly as planned plus or minus a few minutes. This system has almost eliminated the past phenomenon of the “holding pattern”, i.e. circling over airports trying to land. It saves a lot of fuel and some time.


A combination of technology (computers, radar, navigation systems, flight control systems, onboard avionics and communication) and humans (pilots, air traffic controllers) orchestrate the moving patterns in the sky. Similar and probably even more complex sets of methods are used to manage the madness on the ground. The top 16 busiest airports in the world are all located in the United States. Traffic controllers, ticket agents, baggage handlers, gate agents, security personnel, caterers and in-flight crew along with telephones, radios and a plethora of hi-tech gizmos handle the flood of humans and metallic flying objects at these end-points.


The US airlines operate a “hub-spoke” routing system. A large airline handles about 200 cities in the US. To enable people to go from anywhere to anywhere, they bring them to a central location, for example Delta Airlines uses Atlanta, in Georgia, as its hub. On a typical hour in Atlanta, a wave of aircraft hit the tarmac from many of these 200 cities. People swarm out of them scurrying to find the next flight. Suddenly in about an hour the airport is empty as all these planes head off to various destinations, after a major shuffle of passengers. Immediately thereafter the next incoming wave starts up. Frequent fliers of Delta have been heard to say that when you die, and are on route to heaven, you are forced to make a stop at Atlanta.


The number of routes and the number of aircraft flying them are just absolutely astounding. In terms of “aircraft movements” the busiest airport in the world is in Atlanta. An aircraft movement is a takeoff or landing. In 1999 Atlanta Hartsfield International airport reported 909,911 aircraft movements. That translates to 2493 movements a day. If these movements were evenly spread over the 24 hours a day (they are not), it would mean a takeoff or a landing every 34 seconds. That is an amazing amount of traffic to squeeze into the four runways at Atlanta.


Atlanta is not unique. Chicago is a close second (896,228) followed by Dallas (831,959). Following the top three, are Los Angeles, Phoenix, Detroit, Las Vegas, Oakland and Miami. For airports outside the US, the busiest is Paris (rank 17), followed by London (rank 21) and Toronto (rank 28) and Amsterdam at (rank 29). To put things in perspective, the busiest airport in India is Mumbai with 315 movements a day (rank 180) followed by Delhi with 243 movements (rank 221). The other two major cities boasts 111 movements at Chennai and 78 at Kolkata.


The downside of computer technology is that it has enabled the airlines to pursue an aggravating ticket pricing strategy, often called “Yield Management”. Seats on the same flight, between the same two cities are put into fare buckets, ranging from quite inexpensive to astronomical. Then, using computer tracking models the fares are changed, or the number of seats in each fare bucket is adjusted, often many times a day, to ensure profits are maximized. To aid in the profit maximization, an amazing array of restrictions and rules steer the prospective buyer to the higher priced buckets.  This hi-tech jugglery is very irritating to the traveling public and you never are sure what the ticket price would be, until you actually purchase the ticket. Currently, the round trip fare, in economy class, for a trip from Los Angeles to New York is listed as varying from $198 to $2,434. Yield management is an unfortunate marriage of computing and marketing.


Tickets prices, however has declined substantially in inflation adjusted terms ever since the US airline industry was deregulated in 1970. Deregulation fever is not spreading to other countries specially Europe. Under the “Open Skies” initiative many countries are toying with the idea of allowing any airline to operate any sector and charge whatever they feel like. If and when this happens, it will usher in a yet another major advance in international air transport.



Partha Dasgupta is on the faculty of the Computer Science and Engineering Department at Arizona State University in Tempe. His specializations are in the areas of Operating Systems, Cryptography and Networking.


 Partha Dasgupta