Expert: Paul Soderman - 5/13/2009

Question
QUESTION: why does it take a shorter time to fly back from the East to west on airplane......

ANSWER: Salman
Your question is a little vague, so I am going to assume you mean... why do aircraft fly faster in the easterly direction.  The answer is that the jet stream blows from west to east at 10 km altitude.  So an aircraft flying from west to east gets a boost from the wind.  An airplane flying east to west has to fight a headwind.  Wind makes a big difference to aircraft, and though the jet stream wanders, it is very consistent as to direction.
Paul

---------- FOLLOW-UP ----------

QUESTION: Hi Paul,
I thank you for prompt reply. My actual was the time becomes shorter when the plane takes flight from the east to west Eg:the flying time from Bangkok(Thailand)  to Colombo (Sri Lanka- where I am writing to you from)is shorter than time taken fro Colombo to Bangkok. If you say it the Jet stream or the wind, does the wind blow in same direction everyday of the year?
thanks
Salman

Answer
Sorry Salman, my answer was incomplete as I was thinking of the winds at high altitude over North America which is my personal experience. Those winds wander, but are fairly consistent.  The winds over south Asia may be much different, and probably vary with altitude and season.  Perhaps the trade winds dominate in your area, which I believe blow east to west.  You can do a google search on jet stream or wind patterns to see the trends in your area. The bottom line is that aircraft flight time is a direct function of wind.
Paul