katanapilot
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A340-313x Long Haul Question

Thu Jun 13, 2013 3:37 am

Please don't burn me at the stake! I'm not incredibly knowledgeable about such things.

In September 2004 I flew from JFK-ANC-TPE on a CI A340-313x. It was a lovely couple of flights and all was well. On the way home I got on the plane expecting a TPE-ANC-JFK flight but was amazed when I looked at the flight map and saw I was in for a 16.5 hour non-stop to JFK! I've been thinking about this for a long time and finally looked up some stats.

According to the Great Circle Mapper the flight is 12,566kms direct. As far as I know flights are never exactly direct. According to Wikipedia the range of the A340-300 is 13,700kms fully loaded, and my flight was pretty much loaded. I don't know how much tailwinds increase the range but it still seems really close.

Do airlines often push their range that close to the limit? Assuming there was some variance in the flight path, we must have been running on fumes by the time we landed!

I hope someone with some technical knowledge can put my mind at ease and tell me I wasn't as close to dying as I felt I was :p
 
CXfirst
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 3:51 am

Don't think you needed to worry.

Currently, EVA flies their 777-300ER non-stop in both directions. And using the same source (wiki) the range of the 77W is less than 1000km more. That advantage in difference is almost (if not completely) lost in flying the west-bound direction (against jet stream mainly). So, the fact that you flew non-stop Eastbound would have been fine, especially as you were under the prescribed non-stop distance for a fully loaded flight going Eastward.

-CXfirst
 
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zeke
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 3:55 am

Quoting katanapilot (Thread starter):

I have done a few HKG-YYZ flights (just a few miles more) direct on the A343, it can do it, however it is payload limited. We ended up doing it via ANC on a regular basis in the end in both directions to uplift more cargo. Then replaced it with the A346 and 77W which could do it direct with less payload restrictions.

It is not unusual on the way over to YYZ to route further south (closer to the YVR track) than the great circle track to take advantage of tailwinds, this increases the ground miles by at times 600 nm, however with the tailwinds, the air nm is less than the great circle tracks plus its wind component.
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DexSwart
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 4:52 am

QF push their 744s from SYD to JNB.
I fly that route more than any other, and I've seen everything from 10 hours on JNB - SYD to 16.40 hours on SYD - JNB.
There's no where to divert to, other than to take a pretty sizeable detour north to PER or MRU mid flight.
Never had a problem, an airline wouldn't send an aircraft on a route without being sure it can cover the flight.
Sometimes, factors do force diversions, but other than a few uncomfortable passengers, airlines usually push their a/c.
Durban. Melbourne. Denver. Hong Kong.
 
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Starlionblue
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 10:27 am

Quoting katanapilot (Thread starter):
According to the Great Circle Mapper the flight is 12,566kms direct. As far as I know flights are never exactly direct. According to Wikipedia the range of the A340-300 is 13,700kms fully loaded, and my flight was pretty much loaded. I don't know how much tailwinds increase the range but it still seems really close.

Several factors at work here:
- Wikipedia only states the "nominal" range from what I presume are the marketing materials. It also only states one range, which might well be the one for the -300, not the -300x.
- While the plane might have seemed fully loaded, it might not have had a full load of cargo.
- Range decisions are impacted by things like Decision Point Procedure, in which case alternate fuel to be carried goes way down.
- Only Nautical Air Miles count for range. As an example, a 50 knot average tailwind over a 6785 nautical ground mile route in 14 hours means 700 more nautical air miles than nautical ground miles. That's about 1300km.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
vikkyvik
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 3:35 pm

Quoting Starlionblue (Reply 4):
As an example, a 50 knot average tailwind over a 6785 nautical ground mile route in 14 hours means 700 more nautical air miles than nautical ground miles.

700 less nautical air miles?
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Starlionblue
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 7:49 pm

Quoting vikkyvik (Reply 5):
Quoting Starlionblue (Reply 4):
As an example, a 50 knot average tailwind over a 6785 nautical ground mile route in 14 hours means 700 more nautical air miles than nautical ground miles.

700 less nautical air miles?

Yes, of course you are correct. Oops! 
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roseflyer
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RE: A340-313x Long Haul Question

Thu Jun 13, 2013 8:28 pm

Quoting katanapilot (Thread starter):

Do airlines often push their range that close to the limit? Assuming there was some variance in the flight path, we must have been running on fumes by the time we landed!

Airplanes don’t have a specific range. There is a payload – range curve. More payload = less range. Usually the numbers quoted by Airbus and Boeing are full tank range, which is a significant payload penalty. Also, wind factors in to as it affects the air miles flown. You might have been on a plane lightly loaded with cargo that helped it go nonstop.

Also, don’t worry about landing on fumes. You probably landed with more or the same fuel on board than you would have if you had stopped in ANC. Usually international flights are dispatched with the same amount in reserves that account for emergency reserves, anticipated holding time and weather diversion fuel if applicable. Rarely do airlines ever dispatch to a destination and then change in flight due to fuel burn restrictions. Occasionally it happens, but unless there is unanticipated weather or flow control upon arrival, fuel diversions due to range limitations are rare.
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Qantas744er
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RE: A340-313x Long Haul Question

Mon Jun 17, 2013 4:13 pm

Quoting DexSwart (Reply 3):
I fly that route more than any other, and I've seen everything from 10 hours on JNB - SYD to 16.40 hours on SYD - JNB.

I can guarantee you that you have never been on a 16h40m SYD-JNB.

The westbound sector ranges from ~13h30m to ~14h45m depending on the weather/winds aloft etc.

The current southern hemisphere winter average is about 14 hours, with the summer being ~13h15m.
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