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Headwinds Question  
User currently offlineFCA787 From United Kingdom, joined Sep 2006, 19 posts, RR: 0
Posted (7 years 10 months 2 weeks 2 days 4 hours ago) and read 5999 times:

Hi

I have a question about headwinds.

I have been a flight from JFK-LHR a few months ago and it took approx 8hr30mins as their as alot of headwinds the captain said, but I also have done this flight about 2 yrs ago and it took just over 6hrs?.

Has anyone ever been on a flight that has had to put down and refuel because of headwinds?

How long could headwinds potentially prolong a flight by?

Is their a specific flight that is operated regular that you know has to put down regular because of hadwinds?

Do headwinds vary from times or the year? Is their a particular bad time for them?

Cheers

19 replies: All unread, jump to last
 
User currently offlineFlyboy2001 From Canada, joined May 2005, 186 posts, RR: 0
Reply 1, posted (7 years 10 months 2 weeks 2 days 3 hours ago) and read 5980 times:

Well, as a private pilot, I don't deal with those kinds of extremes but my understanding is this... certain routes will nearly always encounter strong headwinds in one direction and a tailwind in the other. Crossing the Atlantic means dealing with the Jetstream but, depending where the Jetstream is flowing that week, one may encounter more or less of it. Flightplans will be made to take advantage of a strong tailwind or avoid a vicious headwind. However, at some point during the year, it is conceiveable that you could find a flight which can't avoid a trans-oceanic track with bad headwinds because of distance/fuel considerations or ETOPS rectrictions.

I've never heard of a flight that had to put down and refuel due to enroute headwinds, most likely because the winds aloft are pretty well predicted and airlines will route their planes around the winds or fuel them for a longer time in the air.

If the flight is long enough, a 100kt headwind can add quite a bit of time to your flight. A simplified example: If your 500kt jet hits a 100kt headwind, the effective forward progress is at 400 kts. Carry that forward, say... 10 hours and you've gone 4000 nm, when you wanted to have done 5000. That's an extra 2.5 hours still to go.

That said, I have never been on any flight that varied as much as your 6 hour vs. 8.5 hour journey!

Hope this helps!  Smile



And you... Revolution, or just resistance?
User currently onlineGoldenshield From United States of America, joined Jan 2001, 6039 posts, RR: 14
Reply 2, posted (7 years 10 months 2 weeks 2 days 3 hours ago) and read 5971 times:

Quoting Flyboy2001 (Reply 1):
I've never heard of a flight that had to put down and refuel due to enroute headwinds, most likely because the winds aloft are pretty well predicted and airlines will route their planes around the winds or fuel them for a longer time in the air.

There are times when an enroute diversion is needed when, in the opinion of the PIC or dispatcher, the flight cannot be completed with the fuel remaining. The chance of this happening is pretty rare, but it does happen, and he may, or may not, be correct.

Also, here in the U.S., winds aloft are published twice a day, so when a flight is planned and departs when another chart is due out, planned and actual can very well vary signifigantly.

Quoting Flyboy2001 (Reply 1):
However, at some point during the year, it is conceiveable that you could find a flight which can't avoid a trans-oceanic track with bad headwinds because of distance/fuel considerations or ETOPS rectrictions.

There are times when you just have to suck it up and fight the wind. Case in point, last month, the jet stream pretty much spread itself out over the eastern half of the U.S. There was no avoiding from Atlanta to Maine.

Quoting FCA787 (Thread starter):
Do headwinds vary from times or the year? Is their a particular bad time for them?

In the summer, the jet stream tends to hang out closer to the poles, rarely venturing south (or north, in the Southern hemisphere.) In the winter, the cooler air brings the jetstream out to play for the winter causing all kinds of problems, like bad winds, and CAT, among other things.

Quoting FCA787 (Thread starter):
Is their a specific flight that is operated regular that you know has to put down regular because of hadwinds?

While no airline wants to have a fuel stop, there are times when one may be called for. If the winds are bad enough on a certain route, and the fuel required to depart is greater than the tanks can hold, there is most definately going to be a fuel stop.

[Edited 2006-11-12 11:51:19]


Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineFlyboy2001 From Canada, joined May 2005, 186 posts, RR: 0
Reply 3, posted (7 years 10 months 2 weeks 2 days 2 hours ago) and read 5938 times:

Quoting Goldenshield (Reply 2):
There are times when an enroute diversion is needed when, in the opinion of the PIC or dispatcher, the flight cannot be completed with the fuel remaining.

Well how 'bout that... Nice to get a Dispatch POV. How frequent (or infrequent) are these instances?



And you... Revolution, or just resistance?
User currently onlineGoldenshield From United States of America, joined Jan 2001, 6039 posts, RR: 14
Reply 4, posted (7 years 10 months 2 weeks 2 days 2 hours ago) and read 5923 times:

Quoting Flyboy2001 (Reply 3):
How frequent (or infrequent) are these instances?

There are too many variables to give an accurate number, but you are looking in the range of 1:500,000+ for unplanned fuel diversions in a commercial operation.



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 10 months 2 weeks 1 day 21 hours ago) and read 5837 times:

Quoting FCA787 (Thread starter):
Do headwinds vary from times or the year? Is their a particular bad time for them?

To illustrate what Goldenshield mentioned, here's a prog chart for later today.

As you can see, the heavy green lines indicate the location and orientation of the jetstream winds, and for this specific chart time of 00Z, and where they're anticipated to be at that time. The jetstream is constantly in motion, and the location and orientations change. Two days from now, the jetstream could be blowing on a straight line from LAX-JFK, or oriented some other way.

The green triangle barbs are 50 knots of speed, and the green lines are 10 knots, so if you had 2 triangles and 2 lines, that speed would be 120 knots. The yellow dashed lines indicate areas of turbulence, which we dispatchers seek to avoid, or plan the the flights to stay under.

http://i34.photobucket.com/albums/d143/OPNLguy/HISIGPROG.jpg


User currently offlineFuturecaptain From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 10 months 2 weeks 1 day 20 hours ago) and read 5817 times:

So, it looks like a flight from JFK-LHR today could have anywhere from 120-150 knots of tailwind today.
The flights going in the opposite direction will be fighting this same wind. Ouch.

[Edited 2006-11-12 18:16:47]

User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 10 months 2 weeks 1 day 20 hours ago) and read 5794 times:

Quoting Futurecaptain (Reply 6):
The flights going in the opposite direction will be fighting this same wind. Ouch.

Not necessarily. If they flew that exact opposite direction, sure, but westbound flights are normally planned on routes that take them out of the jetstream as much as possible so they'll save time/fuel...


User currently offlineNcfc99 From United Kingdom, joined May 2005, 740 posts, RR: 0
Reply 8, posted (7 years 10 months 2 weeks 1 day 18 hours ago) and read 5749 times:

A couple of years ago I flew LGW-SFB. Outbound was 9.5 hours due to weather, northerly routing over southern greenland and down the east coast. Inbound the arriving flight was late, bad weather over the Atlantic again but the captain needed to make up time so we went straight through the weather and encountered bad turbulance. 7 hours to get home. Not nessissarily due to headwinds but a 2.5 hour flight difference due to weather.

User currently offlineTristarSteve From Sweden, joined Nov 2005, 4009 posts, RR: 33
Reply 9, posted (7 years 10 months 2 weeks 1 day 18 hours ago) and read 5737 times:

Quoting OPNLguy (Reply 7):
Not necessarily. If they flew that exact opposite direction, sure, but westbound flights are normally planned on routes that take them out of the jetstream as much as possible so they'll save time/fuel...

Briefly the North Atlantic tracks are set twice a day. Early morning for Westbound and late afternoon for Eastbound. Specific airlines' flight planning offices calculate the best track for the day, and the Atlantic controllers work out a mean, and then publish the five tracks for the day. Eastbound flights look for the best tailwinds, and Westbound flights look for the smallest headwinds. The Eastbound and Westbound tracks will be hundreds of miles apart.
I am not invloved because the transatlantic track from ARN is North of the tracks and joins them usually over Canada.


User currently offlinePPVRA From Brazil, joined Nov 2004, 8964 posts, RR: 39
Reply 10, posted (7 years 10 months 2 weeks 1 day 18 hours ago) and read 5731 times:

I've heard that sometimes AR aircraft flying MAD-EZE have to stop at GRU for refuelling due to headwinds. I don't think it hapens very often, however.


"If goods do not cross borders, soldiers will" - Frederic Bastiat
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 11, posted (7 years 10 months 2 weeks 1 day 16 hours ago) and read 5658 times:

Quoting Goldenshield (Reply 2):
Also, here in the U.S., winds aloft are published twice a day, so when a flight is planned and departs when another chart is due out, planned and actual can very well vary signifigantly.

The winds aloft forecasts are usually way off. They get the general direction right, but the speed varies widely.



09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 12, posted (7 years 10 months 2 weeks 1 day 16 hours ago) and read 5641 times:

Quoting OPNLguy (Reply 5):
o illustrate what Goldenshield mentioned, here's a prog chart for later today.

Would such a map be available online?
I'd like to plan my "virtual" flights better but have not been able to find jetstream info anywhere.



The conveyor belt plane will fly
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 13, posted (7 years 10 months 2 weeks 1 day 12 hours ago) and read 5600 times:

http://adds.aviationweather.gov


09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 14, posted (7 years 10 months 2 weeks 1 day 10 hours ago) and read 5580 times:

Quoting Ralgha (Reply 13):
http://adds.aviationweather.gov

...and click the tab for "Prog Charts"

...and on the right side, click on "Hi Level"

...and go down to "Mercator" and mouse-over the area you want to cover...


User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 15, posted (7 years 10 months 2 weeks 1 day 6 hours ago) and read 5540 times:

Thanks!  Smile
That was the page I had missed. Didn't think global data was available there.

A followup question: The jetstreams are labeled with a FL, the question I have is how close to that FL do I have to fly to use the jetstream? If I fly higher, at what level will I leave the jetstream?

In short, how "thick/deep" are the jetstreams?



The conveyor belt plane will fly
User currently onlineGoldenshield From United States of America, joined Jan 2001, 6039 posts, RR: 14
Reply 16, posted (7 years 10 months 2 weeks 9 hours ago) and read 5453 times:

Quoting Ralgha (Reply 11):
The winds aloft forecasts are usually way off. They get the general direction right, but the speed varies widely.

And yet, you'd be surprised at just how accurate flight plans made from them can be.

Quoting Chksix (Reply 15):
A followup question: The jetstreams are labeled with a FL, the question I have is how close to that FL do I have to fly to use the jetstream? If I fly higher, at what level will I leave the jetstream?

The green lines on the charts just show the centerline of a projected path of the jetstream. They can in fact be hundreds of miles wide and thousands of feet deep.



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineOPNLguy From , joined Dec 1969, posts, RR:
Reply 17, posted (7 years 10 months 2 weeks 1 hour ago) and read 5408 times:

Quoting Chksix (Reply 15):
In short, how "thick/deep" are the jetstreams?

In my experience, flight planning at FL220, FL240, or FL260 usually gets you under the core of the strongest winds....


User currently offlineBond007 From United States of America, joined Mar 2005, 5417 posts, RR: 8
Reply 18, posted (7 years 10 months 2 weeks ago) and read 5392 times:

Quoting Goldenshield (Reply 2):
There are times when an enroute diversion is needed when, in the opinion of the PIC or dispatcher, the flight cannot be completed with the fuel remaining. The chance of this happening is pretty rare, but it does happen, and he may, or may not, be correct.

Although a month or two ago, there was a whole bunch of East Coast - West Coast flights over a period of a few days, that had to stop for fuel somewhere on the way. The winds were extremely strong. I seem to remember a few airports getting some unusual visitors!


Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineChksix From Sweden, joined Sep 2005, 345 posts, RR: 4
Reply 19, posted (7 years 10 months 1 week 6 days 21 hours ago) and read 5373 times:

Thanks Goldenshield and OPNLguy  Smile

It'll make the virtual flights a bit more realistic...



The conveyor belt plane will fly
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