Hi Dan, good to hear from you!

 

Perhaps that was what I experienced recently going into YSSY from VHHH. On descent I was surprised at the sudden strong turbulence (ASN) and had difficulties controlling the aircraft for an approach to 34L.

 

Of course the jet stream would only have accounted for the high altitude turbulence, but I was proud of my abilities to cope with all that was thrown at me.

 

Regards, Richard

Hi Richard, I will occasionally use SkyVector with satellite wx and wind barbs enabled (see Layers options) to see significant weather while oceanic. It takes a few minutes to enter the flight plan but when doing so there's not much need to enter every waypoint as long as you can select a point within several hundred miles of your enroute location. My flight was a very fictional KIAH-YSSY, which in the -200LR is well within range (assuming ETOPS330) but stretching the limit of the -300ER that I tested on this trip. ASN enroute winds were not as close to actual simulated as was SkyVector thus the surprise.

Still waiting for Kyle or Rob or someone other to give us some info about LRC here... :-)

I appreciate the vote of confidence.

 

Remember that aviation is constantly evolving, and we occasionally carry old methods into new realms of technology for familiarity's sake.

 

Case-in-point: VOR and NDB approaches.  Even though most fleets and even GA aircraft have some form of IFR-approved GPS, we keep these things around.  They aren't usually used, but they're still there.

 

Same thing goes for LRC (and MRC for that matter).  CI came as an evolution of those concepts, because it takes into account wind among other factors.  If the air were completely still, LRC and MRC would give you max range values, but the air isn't still, and there are other factors into flight costs.

 

Note the bolded and italicized text over the graph in this article:

http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/article_05_2.html

 

(It's also worth reading the article.)

Thanks for clarification Kyle. So summed up: you'll never use LRC but instead enter CI 0 if you have massive fuel problems.

Thanks for clarification Kyle. So summed up: you'll never use LRC but instead enter CI 0 if you have massive fuel problems.

 

That's the guidance I've seen from Boeing, and they're the ones with the data to back up the claims, so I'll gladly listen to them...haha

 

 

if you have massive fuel problems.

Could you indicate an example of "massive fuel problems"?

Could you indicate an example of "massive fuel problems"?

 

My understanding was that he was referring to having a shortage of fuel at the destination, given the current CI.

Could you indicate an example of "massive fuel problems"?

 

I do not know if this is realistic but let's assume you've calculated much too optimistic (low cost carrier) and get some stronger headwinds and also a forecast of some holding's because of bad weather. I can imagine you'll try to set CI to 0 if it is possible to not do an extra fuel stop.

I can imagine you'll try to set CI to 0 if it is possible

 

 

When I do the planning with PFPX I use a CI of 20 for the LR and 40 for the freighter. PFPX wind forecasts seem reasonable so I never have encountered a fuel issue. I will try switching to CI 0 midflight sometime and see how much that increases the reserve fuel. Thanks.

EDDP-KLAX 1.5 hrs into 11.5 hrs flight. Changed CI from 40 to 0. Speed decreased from .826 to .822. ETA went from 1450Z to 1456Z. Remaining fuel at KLAX increased from 27.7 to 28.6. Hardly worth the effort.

Michael,

I agree unless you were dangerously short of fuel. At around $1000 per tonne, that is still a good saving, and shows how airlines have to balance speed with fuel costs..

Even so, interesting numbers.

Cheers, Richard

 

 

Hardly worth the effort.

 

Tell that to the bean counters...

EDDP-KLAX 1.5 hrs into 11.5 hrs flight. Changed CI from 40 to 0. Speed decreased from .826 to .822. ETA went from 1450Z to 1456Z. Remaining fuel at KLAX increased from 27.7 to 28.6. Hardly worth the effort.

Hi Michael,

 

I this this is a fairly big difference considering you were using a cost index of 40, you could use a higher cost index of 85 like I do.  I bet then you would see a substantial difference.  The changes in Z time only being 6 min i think the airlines would take $1000 for 6 min.

 

Marc 

Do this 40 times a day and you save 40000, which makes half a million in 12 days big peanuts