Mdjtlj From United States of America, joined Jun 2000, 12 posts, RR: 0 Posted (13 years 5 months 2 weeks 2 days 3 hours ago) and read 2315 times:
Recently was on a flight from AMS-NRT (KLM 863) that was quite strange in terms of timing.
See the following excerpts from the timetables:
KLM 861 (All days except Tuesday) 14:40-8:45+1 Dur. 11:05 hours
KLM 863 (Tuesday) 12:55-09:00+1 Duration 13:05 hours
The only other difference between the two is the aircraft (KLM861 747 Passenger, KLM863 747 Combi).
There was no stop en-route (which would have been my first guess) and the flight did take a full 13:05 hours. The only thing I could come up with on the length is that the routing was very circuitous (i.e. over Turkey, Jordan, Iran, India, China) and was defintely not close to great circle.
Does anybody out there know if the routing for the other days is any different and if so why?
Mdjtlj From United States of America, joined Jun 2000, 12 posts, RR: 0 Reply 3, posted (13 years 5 months 2 weeks 2 days 1 hour ago) and read 2145 times:
Unfortunately, I don't think it had anything to do with the Combi versus Passenger derivative issue, as Boeing gives the "typical cruise speed" as 565 mph for both models.
Just for grins, if the route were the same (i.e. 5836 miles via great circle) the speed of the passenger would be 526mph and 446 for the combi. This, I believe would rule out differences in the weight/speed or engine suggestions previously given as the difference is just too much.
KLM also uses the combi on the IAH-AMS route and the average speed developed on this route is 536 mph (great circle = 5004 miles and duration is 9:20)
This therefore, leads us back to the routing. Does anybody have suggestions as to the large difference? Seems very incredulous that on one day, it takes two hours longer which could be equated to 1000+ extra miles on the flight path.
A330 From Belgium, joined May 1999, 649 posts, RR: 8 Reply 4, posted (13 years 5 months 2 weeks 1 day 19 hours ago) and read 2082 times:
It is the Jetstream, I presume.
This is a continuous wind blowing around the world at a height of approx. 30.000 ft., at the Tropopause.(-56°C) This wind blows from West to East, like the earth rotation.
So, going to Europe from North America, and going to the Far East from Europe takes less time, because you have the Jetstream in your tail.
SabenaA320 From Belgium, joined Nov 1999, 114 posts, RR: 0 Reply 5, posted (13 years 5 months 2 weeks 1 day 17 hours ago) and read 2067 times:
Perhaps this reason:
On all days excepts tuesday they fly via Siberia and Russia. And on Tuesday they fly via Turkey, Jordan,... I think that must be a little bit longer. Normally the flight would go via Siberia.
Mdjtlj From United States of America, joined Jun 2000, 12 posts, RR: 0 Reply 6, posted (13 years 5 months 2 weeks 1 day 16 hours ago) and read 2060 times:
A330 - All flights mentioned were from West to East and should have approximately the same effect from the jet stream.
SabenaA320 - I think your comment is probably the most viable and logical. But there still is the lingering question, why would the routing be consistently different on Tuesday only? Is there some aviation treaty that limits overflights of certain parts of the former Soviet Union only on this day, an ATC issue, etc....?
Mas777 From United Kingdom, joined Jul 1999, 2926 posts, RR: 6 Reply 8, posted (13 years 5 months 2 weeks 1 day 3 hours ago) and read 1993 times:
The reason behind the discrepency is the fact that not all Europe-Far Eastern flights can overfly Russian airspace. The preferable route for AMS-NRT is to head towards Moscow and then over Siberia before overflying South Korea and into Japan. Presumably KL861 uses this routing whilst KLM has not been approved by the Russian authorities to operate this service more than 6 times a week - so KL863 has to fly via a more Southerly route via Turkey - adding to its flying time.