How come flying times vary in a round-trip?

Question

For example, I frequently fly between two fixed cities in California and Florida, respectively. Going from California and Florida, it always takes 5 hours and 10 minutes or so. Flying back, it always takes 6 hours and 30 minutes or so. What accounts for this difference?

Answer 1

Well, there's two basic answers... 1) equivalence of motion 2) physics.

1) Equivalence of motion: it doesn't matter whether you move or the earth moves. Either way you perceive the earth to move relative to you. But if you're BOTH moving it appears one or the other is going faster or slower. So, if you're moving at 5 mph toward something from a 3rd party vantage point, and it's moving toward you at 5mph relative to a 3rd party vantage point, it appears they're moving toward each other at 10 mph, and if they collide (like on a highway) 10mph worth of energy is involved in the exchange, but that's neither here nor there.

Likewise, if you're both moving in the same direction, say you're moving 5 MPH, and something else is moving 2 mph, you appear to be moving 3 mph relative to the object in question, or approaching it at 3 mph, since you're going 3 mph faster than it is.

So, assuming you're flying, this same principle applied. When you fly one direction, you're traveling in the opposite direction from the earth, thus you seem to be moving faster (you're adding your velocity to the velocity of the earth relative to you). But, when you're flying the other way, you're traveling the same direction, thus you're playing catch up (so you are subtracting the speed of the earth's roation from your speed thus making it appear to move slower relative to you).

2) Physics: rotating earth is smaller than the atmosphere that extends up toward space. Planes travel at a much higher level than the surface of the earth. Things tend to spin more slowly at higher altitudes. You have to cover more distance with the same velocity, so it takes longer. So, the earth is spinning faster than the atmosphere slightly. This creates wind systems (IE, the headwinds, tailwinds and jetstreams others are talking about). Headwinds add drag to the plan thus slowing it down further. Tailwinds add to the velocity of the plane, thus speeding it up. So, likely you're getting a tailwind going one way and a headwind the other...

Hopefully that covers the two camps... w00t! next?

Answer 2

As many people have already stated, there are a few reasons for your observed variance in travel times. Two of the most common answers: flying along with the jet stream and the rotation of the earth are both correct, but another thing to think about is what kind of plane you are on. Different types of planes can fly at different speeds safely. An Airbus A320 cruises at 504 MPH, while a Boeing 737 can fly at 593 MPH, which, over a long flight, can be quite significant.

Answer 3

The Jet Stream, a high altitude area of winds, is the reason.

When you fly from California to Florida, you're flying with the jet stream. The 100 (or more) mph winds blowing your airplane towards Florida really help to get it there faster. On the way back, you're flying against the jet stream, so it will slow your plane down a whole lot.

Answer 4

Two major reasons. Long range flights are at high altitude and are influenced by the jetstream, so there is a high speed tailwind west-to-east and high speed headwind when you're flying east-to-west.

Also, the earth is turning west-to-east under you as you fly, making the trip shorter flying westward.

Answer 5

Another variable besides the wind, would be the plane that is making the trip. You may be on a smaller or larger aircraft which may cruise at a different speed.

Answer 6

The jet stream generally blows from west to east, so the east bound flights usually have a tail wind and the westbound flights usually have to fight a headwind.

Answer 7

Tail winds, these winds can add or substract from your ground speed and they are always blowing in one direction at the height at which jets travel. Therefore in the direction of the jet stream you will go faster and opposing the jet stream you will go slower.

Answer 8

The head wind and tail wind. Usually the wind flows from west to east. So goin east is faster and return to west is slower.

Answer 9

the wind direction affects the speed of the plane

Answer 10

It's because of the head wind and tail wind. If it's behind you, you go faster