Headwinds and Tailwinds

The line before security clearance at Philadelphia International Airport was quite long on Monday morning and growing by the minute.  As it was the first working day after a long weekend and New Years day celebrations, all morning flights were fully booked and everyone was in a hurry to get cleared through the security gates.  It appeared that my flight may be missed due to delay in clearance as there were dozens of others ahead of me.  A good samaritan helped clearance of passengers for flights taking off in the next few minutes on urgent basis and I was the last passenger to board our flight.  As I squeezed into my seat between two other passengers, take-off was announced.  "Even the darkest cloud has a silver lining", they say.  That was true here as I was spared the usual long wait at the boarding gate.

The pilot announced that the flight to Seattle on the Pacific coast would take five hours and four minutes.  As the aircraft took-off and started gaining altitude, the person sitting on my side asked me what the time was.  When I replied that it was 7.50 AM,  he said "See, the flight is already 20 minutes late.  Time table says the flight takes six hours.  Pilot says it takes five hours and four minutes.  How it is possible?  I do not understand".  He appeared frustrated and I felt it was better to leave the issue at that instead of explaining the situation to him.  I was actually happy that the flight was 20 minutes late or else I may have missed it.

What my fellow passenger did not realise was that we were the luckier lot as our flight was not cancelled, unlike thousands of flights from cities like Chicago and St. Louis.  North America is reeling under the effect of a phenomena called by meteorologists as "Polar Vortex" and described as "Polar Pig" by the media.  Polar Vortex has brought down the temperatures to as low as minus 50 degrees celsius in some areas.  Airport operations are hit as aviation fuel froze in the sources and the crew were unable to fill aircraft tanks.  Many inches of snow has rendered venturing outdoors a high risk idea. Schools are closed and people have been advised to stay indoors.  In many cities driving has been banned except in emergency situations. Icy roads and sidewalks have made journey on the roads treacherous.  We were at least airborne and on our way though the pilot warned us of a bumpy ride, in his own very polite language.  Despite this, journey by air was far more safer than on the icy and windy roads in life threatening temperatures.

How does the actual flight time happen to be much lower than the time displayed on time tables?   Timetables refer to terminal-to-terminal time while pilots refer to actual flight time between take-off and landing.  Transport operators, whether by road, rail or air, usually provide a cushion for the unexpected delays that may take place during the actual travel.  On time arrival at destinations is one key performance parameter for transport and airline companies.  A slightly extended journey time provides buffer to absorb unexpected delays in starting time and delays on the way.  Hence the arrival of the destination would be as per schedule despite slight delays at the starting point.  The on time performance figures are thus protected and make for good reading and publicity.  In the case of airlines, there are also likely delays due to clogging of runways and weather related issues.  If the take-off is on schedule and everything else also goes fine, arrival at the destination may even be before scheduled time.  Besides this, scheduling flights this way make further utilization of the aircraft more scientific and practical.

In the case of air travel, wind factor is a key influence in the actual journey time.  "Head wind" and "Tail wind" are two components that affect the duration of the flight.  A headwind is a wind blowing against the direction of the travel and a tail wind is a wind blowing in the direction of the travel.  In the case of aircrafts, headwind has the effect of decreasing the speed of the plane whereas the tailwind adds to its speed.  Journey in the air with tail wind is, therefore, faster than journey with a headwind.  For this reason, actual time of journey between two places in the same direction may vary on different days and even at different times on the same day.  Proverbs in different languages to take advantage of the direction of the wind blowing have been in use for a long long time.  Of course, our politicians have mastered this art perfectly.

Air traffic controls and pilots use the concept of headwind, tailwind as well as cross-wind to advantage in their operations.  Take-offs and landings of aircrafts are scheduled on different runways (in airports with multiple runways) providing headwinds as a headwind is favorable for both take-off and landing.  Tailwinds are favorable when the aircraft is in flight.  When we are engrossed in our own world while traveling, experts at ATC and pilots are busy with all these details.  Thanks to their continuous efforts, air travel is far more safer than travel on the land.  Many may not agree with this but that is what the truth is.  An aircraft tragedy attracts all the more attention and the fear associated with air travel is more in minds than in reality.  Modern aircrafts take every contingency into account and safety standards are upgraded from time to time.  Any accident that happens is like any other mechanical failure and despite all these safety efforts.

While I was contemplating all these issues, the pilot announced landing at Seattle-Tacoma airport five minutes before the expected arrival time.  Despite warnings of the bumpy ride made by him at the time of take-off, the flight was very smooth except for the initial half hour.  The aircraft had left all the cold weather behind and moved to the much warmer western coast.  My co-passenger who expressed his annoyance on the twenty minute delay in take-off was unaware of all these and lost in his wonderful sleep along the entire flight.  He did not get any sweet dreams, I am sure of that for he did not smile even once in his sleep.  I had to nudge him to wake him up as I had to pass him before getting off the plane.

Many thanks to the weathermen who are now able to predict changes in the weather so accurately and the ATC staff and airline crew.  They make air travel a lot safer though it often goes unnoticed.