headwinds and tailwinds

When we fly west over the Pacific Ocean (e.g. California to Bombay) it takes about 22 hours to reach the destination, but it only takes 17 hours back. Is this because when flying from California to India the direction of flight is the same as the direction of the Earth's rotation around its axis, so it takes longer because the destination is moving further away from the plane and the plane is trying to catch the destination? And when flying back the flight direction is opposite of the Earth's rotation and both the airplane and the destination are coming towards each other? Of course the head winds and the tail winds do play quite some role, but I'm guessing that the major factor is the Earth's rotation with respect to the flight direction. Is that correct?
- question from Raj

....

So, the end result of that long discussion is that the rotation of the Earth has no effect on the travel time of an aircraft. Actually, as you suggested, it is the headwinds and tailwinds that cause the change in travel times. Sometimes it is hard to believe that the winds can have that much effect, so let us consider the problem a bit more in depth. In the example given, the flight from Bombay to California (east) is 23% shorter than the trip from California to Bombay (west). This means that the speed of the trip east must be 23% faster. The prevailing winds pretty much anywhere that we are talking about blow from west to east, so when we are traveling east, we get a speed gain, and when we travel west, we get a speed penalty. Now, if we are to assume that the winds are identical on both days we fly, then the wind speed only needs to be equal to 11.5% of the aircraft's speed! This would cause a difference between the speed to the west and speed to the east of 23%! The cruise speed of the extended range Boeing 777 is about 550 mph (885 km/h) at 35,000 ft (10,675 m). This means that the winds only need a speed of about 65 mph (105 km/h) (good kite weather). Believe it or not, 65 mph is a very typical wind speed at such a high altitude. Speeds of over 100 mph (160 km/h) are not uncommon. If we wanted to make things more complicated, we could consider a region of high speed flow called the jet stream that flows eastward, and if an aircraft can take advantage of these winds, then the travel time can be reduced further. (We could get even more complicated and talk about El Nino and La Nina, but I think we have blamed them for enough already!)

So what is the bottom line? The rotation of the Earth does not effect the travel time of an aircraft, and, more importantly, a mere 65 mph wind is more than enough to cause a difference in travel time of five hours when you are traveling long distances!
- answer by Doug Jackson, 20 May 2001
http://aerospaceweb.org/question/dynamics/q0027.shtml