trijetsonly
Posts: 285
Joined: Tue Jul 21, 2009 10:38 pm

Headwind Advantage

Wed Nov 06, 2013 12:26 pm

Hello everyone,
after flying now between a local city pair with ~350km distance inbetween for several years, I made following consideration:


Assuming that you have two airports with the similar runway direction and the direction from one airport to the other is similar to their runway direction:

Until which wind speed and distance between the airports, the flight is more economic with headwind because you don't have to circle or fly traffic patterns on departure and arrival? (no holdings in this case)
So the point is, that the total flying distance is longer with tailwind, because takeoff and landing are in the wrong direction with headwind. How strong has the wind to be, to compensate the total distance flown.... OR how long has the direct distance to be that even a slight tailwind compensates the additional circling/pattern distance?

So I guess one can draw a graph with head-/tailwind speed on one axis and the distance between those two airports on the other axis.
As a result we get a line which shows the breakeven-point.

What do you think about that thought?
Happy Landings
 
oly720man
Posts: 5743
Joined: Fri May 21, 2004 7:13 am

RE: Headwind Advantage

Wed Nov 06, 2013 5:53 pm

There are far too many variables to make a meaningful determination and the likelihood is that any optimum condition will occur so rarely it will be little more than an academic exercise.

The flying distance isn't the issue it's the flying time, fuel's measured in volume per hour. You can fly a longer distance but with a suitable headwind/tailwind a higher ground speed will mean you're not in the air as long as on another day with less wind.

edit

Though having said that there can be ATC procedures in place to improve flight performance by optimising routes and approaches to airports.

[Edited 2013-11-06 10:04:57]
wheat and dairy can screw up your brain
 
rendezvous
Posts: 531
Joined: Sun May 20, 2001 9:14 pm

RE: Headwind Advantage

Thu Nov 07, 2013 2:22 am

It's even better when you takeoff towards your destination, then it changes to a tailwind during the climb. Best of both worlds!
 
bond007
Posts: 4423
Joined: Mon Mar 14, 2005 2:07 am

RE: Headwind Advantage

Thu Nov 07, 2013 7:08 pm

Quoting rendezvous (Reply 2):
It's even better when you takeoff towards your destination, then it changes to a tailwind during the climb.

It's even better if you takeoff and a land on a conveyor belt!

Jimbo
I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: Headwind Advantage

Thu Nov 07, 2013 10:55 pm

if you are saying the wind is constant then a 10 kt tail is max for takeoff so then 10kt headwind for the trip and landing is it.
 
atct
Posts: 2472
Joined: Fri Mar 16, 2001 6:42 am

RE: Headwind Advantage

Fri Nov 08, 2013 2:30 am

All depends on the type of aircraft, runway available . weather, etc.

Taking the KingAir into a 12,000ft dry runway, I'd take a 20kt tailwind component on takeoff or landing to save 5 minutes. When we went into 3000ft runways, always take the headwind and a nice long stable approach. Flying my J3, anything more than 5kts on the tail and I was chirping for into the wind operations. I've landed with a 15kt tailwind in the J3 and its not fun. Many many variables.
Trikes are for kids!
 
skyhawkmatthew
Posts: 322
Joined: Wed Oct 26, 2005 4:42 pm

RE: Headwind Advantage

Sat Nov 09, 2013 9:11 am

Over a 350 km stage length...

Let's assume the time taken to fly a circuit instead of a straight in approach adds 3 minutes to the flight time (ignoring changes in taxi time).

If the sector usually takes 40 minutes to the commencement of the approach, that's an average speed of 284 knots. Taking 43 minutes instead, and making a straight-in approach, such that the overall time spent is the same, requires an average speed of only 264 knots, that is, anything less than a 20 knot average headwind means the straight in approach will save time.

Of course, wind speeds vary dramatically with altitude, so this is a very vague generalisation!
Qantas - The Spirit of Australia.

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