Why does it take approximately two hours longer to travel from London
to the US, than the other way?  Is it anything to do with the rotation
of the earth?

Hi there,

I figured I could answer this question, because every time I fly
between Australia and NZ the same thing happens, and I have always
been told it is because of the wind. Next month my flight to NZ will
take 3.5 hours, and the return trip will take 2.5 hours. When you take
into consideration all the time taken up with takeoff and landing,
that indicates quite a strong wind!

For Heathrow to Chicago:

"I checked the departure and arrival times of a Boeing 777, which has
an advertised cruise speed of 560 mph (900 km/h). After figuring the
time elapsed of each trip, I found that the average speed of the trip
from Chicago to Heathrow is about 525 mph (845 km/h), while the
average speed of the return trip is only about 440 mph (710 km/h)!
Notice that not only are both trips considerably slower than the
published cruise speed, but the return trip average speed is over 80
mph slower than the original flight! "
http://www.aerospaceweb.org/question/dynamics/q0057.shtml

The article goes into much more detail, but declares the main reason
to be wind. It links to a similar question and answer, which dispels
the idea of the Earth's rotation making any difference:

"Now stop running. If you were to jump straight up in the air, would
the Earth rotate beneath you? (Those who do believe that the Earth
rotates around them may want to stop reading right now.) No, because
when you left the Earth's surface, you were traveling at the same
speed as the surface, so, in essence, the Earth matched your speed
through space while you were in the air! The same condition holds true
for an airplane as it travels from Los Angeles to Bombay. If we were
to ignore the winds, no matter which direction you flew from Los
Angeles, the speed of the aircraft relative to the Earth would be the
same. While the aircraft’s speed through space would change, the
effect of the Earth’s rotation remains constant, and in effect is
"cancelled out" no matter which direction you travel. In other words,
the speed of the rotation of the Earth is already imparted to the
aircraft, and the Earth matches that speed during the entire flight.
(Of course, in the case of spacecraft, these speeds become very
important.) "
http://www.aerospaceweb.org/question/dynamics/q0027.shtml


Search keywords: longer london "new york" fly tailwind


Best wishes,
robertskelton-ga

Fascinating stuff.

A slower speed obviously means less fuel consumption which may be
important for airlines that are feeling the pinch.

I wonder if the differential reported holds true for all airlines?

Also, arrival times may be a factor. Are there restrictions on flying
in some parts and at some times that affect one direction but not the
other?

Whilst the headwind/tailwind is the major factor here, I wonder if
slightly different routes each way might also contribute.  There may
be seasonal factors as well.

Also, not to be contrary, but if the the slower speeds are caused by a
headwind as opposed to a lower engine speed, I don't think the fuel
consumption will be better due to the aircraft travelling slower.

Just a couple of thoughts.

The rotation of the Earth has no effect on the time it takes for an
aircraft to fly from one point to another. The aircraft and the air
around it is part of the Earth. It's the same when you jump up in the
air from the ground - you land in the same place.

Airlines do try and make use of the jetstreams where possible. These
are fast moving winds that circle the Earth and move at approx.
300mph.

I disagree with darrenw-ga. No doubt if you jump up into the air, you
would land on the same place where you started. However, this is due
to the miniscule amount which you jumped (one meter)- the earth's
rotation has no visible effect whatsoever. However, for an airplane,
which travels several thousands of miles to reach London, the earth's
rotation would have an effect on the direction of the airplane. This
is called the Coriolis Force.

I'm travelling London -> Miami and vice versa later this month and the
times are 1 hour different. It's to go with the wind (the 'north
atlantic drift'). When you fly London -> USA you fly into the wind, so
the flight takes 9hrs 45mins. On the way back you fly with the wind,
so it takes 8hrs 45mins.

Imagine going to a local restaurant about 1/2 mile away on a windy
day. On the way their you walk against the wind. It's hard work and it
takes 15 minutes. On the way back the wind is behind you, pushing you
home and the same journey takes 10 minutes.

It's the same principal with the flights. It's all about wind
hindering you one way, and helping you the other way. It does make a
big difference (with a strong tail wind you can actually save as much
as 2 hrs USA -> London)

NickB