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Route Planning To Take Advantage Of Thermals?  
User currently offlineFaro From Egypt, joined Aug 2007, 1545 posts, RR: 0
Posted (5 years 4 months 1 week 2 days 9 hours ago) and read 2910 times:

Like with areas with strong tailwinds, do airlines ever route trips over areas of uniform, mildly ascending airmasses, such as benefit sailplane activties? Theoretically, this could reduce fuel burn on overland legs (to the extent that undue turbulence is avoided).

Faro

[Edited 2009-05-13 03:22:41]


The chalice not my son
8 replies: All unread, jump to last
 
User currently offlineOly720man From United Kingdom, joined May 2004, 6734 posts, RR: 11
Reply 1, posted (5 years 4 months 1 week 2 days 9 hours ago) and read 2898 times:

I'd expect that the scale of such atmospheric effects would be too small to warrant the change in routing to use them. And most planes cruise above the weather.


wheat and dairy can screw up your brain
User currently offlineOffshoreAir From United States of America, joined May 2009, 177 posts, RR: 0
Reply 2, posted (5 years 4 months 1 week 2 days 9 hours ago) and read 2896 times:

When I lay out flight plans for the widebodies we schedule in the office I work in, we use different settings of seasonal winds - i.e. 85%, or 75%, depending on the mission. This is mostly just to get a ballpark figure on fuel burn and operating costs. I assume just like intra-US IFR routing, trans-atlantic and trans-pacific routing has preferred routing and travel lanes for crossing the oceans and polar routes that actually must be filed for on the flight plan.

But once you are in the air the game changes significantly. A lot of times pilots' can request deviations or new flight routing in order to hop in the jetstream or ask for different altitudes to avoid turbulence or lessen a headwind. This is especially true for east-bound trans-continental flights in the US. I've read and heard plenty of stories of planes getting in the 700MPH ground speed realm because of a serious tailwind.

Its like the flat escalators underground at ATL - you may have to walk in the wide lanes between the escalators if the faster escalator lanes are too crowded, but if there is room and clearance, you can hop on, exert the same amount of work, but reduce travel time and overall energy used.  Smile

Unless you are about to sit on the ATL-NRT flight for an endless amount of time, in which case I walk the mile



OffshoreAir
User currently offlineMetroliner From United Kingdom, joined Jan 2007, 1067 posts, RR: 1
Reply 3, posted (5 years 4 months 1 week 2 days 8 hours ago) and read 2887 times:

Well, thermals are only one of the types of rising air mass that are out there. It might be feasible to cruise in portions of 'mountain wave' in the lee of a large, relatively straight mountain range. Examples could be the Andes and Rockies, though I don't believe this is done in practice.

This mountain wave lift is associated also with strong turbulence and was responsible for breaking up a BOAC 707 over Mount Fuji back in the day. It shows as lenticular clouds running parallel to the mountains. Whereas I wouldn't wedge a large jet in it, something like a small business aircraft might get some benefits from it - if they didn't mind bouncing around a bit, of course  Smile



Set the controls for the heart of the Sun
User currently offlineRwessel From United States of America, joined Jan 2007, 2352 posts, RR: 2
Reply 4, posted (5 years 4 months 1 week 1 day 21 hours ago) and read 2824 times:
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Most smaller lift source, like thermals and ridge lift, are too small, or meaningful only too near the ground, to be of much use to an airliner. Mountain waves might be big enough, but are often very, very rough (actually pretty much any of the sources of lift can, and often are, pretty turbulent) - not something you really want to subject passengers to.

I can personally vouch for the (potential) roughness of mountain waves - having had one crack my skull against the canopy hard enough to make me see stars - and leave a very nice lump. But other than the lump, that was one *heck* of a soaring day! I topped out at over 22,000ft.  Smile


User currently offlineFaro From Egypt, joined Aug 2007, 1545 posts, RR: 0
Reply 5, posted (5 years 4 months 1 week 1 day 4 hours ago) and read 2746 times:



Quoting Rwessel (Reply 4):
Most smaller lift source, like thermals and ridge lift, are too small, or meaningful only too near the ground, to be of much use to an airliner.

What about depressions? From my climatology primer, they are areas of gently rising air with regional extent.

Faro



The chalice not my son
User currently offlineRwessel From United States of America, joined Jan 2007, 2352 posts, RR: 2
Reply 6, posted (5 years 4 months 1 week 23 hours ago) and read 2709 times:
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Quoting Faro (Reply 5):
What about depressions? From my climatology primer, they are areas of gently rising air with regional extent.

The key is that the air needs to be rising fast enough to be useful, AFAIK, the lifting of the low pressure air mass is pretty slow overall (although it can be locally more intense), although I can't seem to find any typical numbers on that at the moment.


User currently offlineBorism From Estonia, joined Oct 2006, 431 posts, RR: 0
Reply 7, posted (5 years 4 months 22 hours ago) and read 2494 times:

But aren't all those mentioned effects large contributing factors in the formation and location of the jet streams, so airlines are using them indirectly anyway?

User currently offlineYWG From Canada, joined Feb 2001, 1146 posts, RR: 2
Reply 8, posted (5 years 4 months 12 hours ago) and read 2458 times:

jet streams are the result of continental air masses.


Contact Winnipeg center now on 134.4, good day.
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