Sandyb123 From UK - Scotland, joined Oct 2007, 1256 posts, RR: 0 Posted (7 years 7 months 2 days 16 hours ago) and read 15152 times:
I recently took a Virgin Blue flight out of Melbourne for Sydney. It's relatively short hop (at least in Australian terms) at just over 1 hours flight time. However I was very surprised to note that we climbed very close to the service celling of our 737-800 of 12,300 meters (just shy of 40,400 foot). I was wondering why we went so high and can only come up with the following thoughts:
1) We where flying over bad weather, but it was a clear day so not sure?
2) There was a lot of traffic in the area?
3) THe hot air requires aircraft to fly higher to fly efficiently?
4) The air display was broken and we where'nt actually that high.
Any thoughts or ideas are more than welcome. Or is it just an operational thing with Virgin Blue?
FlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 14
Reply 2, posted (7 years 7 months 2 days 15 hours ago) and read 14996 times:
Quoting QantasA333 (Reply 1): Between Adelaide and Melbourne (shorter flight than MEL-SYD)
the plane flew at around 35,000ft. But 40,000ft is more an international flight height.
If I had to guess, I would say that it was traffic. Even if high altitude flying it more typical of longer flights, it's often traffic.
I was on a SFO-TPE on UA in May, we climbed up to 28,000, and got cleared up to 30,000 and could not get cleared any higher (I listened to channel 9 the entire flight) until we had passed Japan. Seemingly every half hour and whenever we changed ATC, the pilot asked for a higher altitude, but there was just too much traffic in the air way.
Must have been fun to climb and drop that fast though!
"Let the world change you, and you can change the world"
YXD172 From Canada, joined Feb 2008, 453 posts, RR: 0
Reply 4, posted (7 years 7 months 2 days 14 hours ago) and read 14900 times:
I think that I once heard a pilot mention that a fully parabolic flight (short cruise) is more efficient than only going up to, say, 25000' and cruising for longer, although it seems counter-intuitive to me.
I asked a WS pilot once after a short flight and he said that they always do that in Canada -- however it's rarer in the US because there's more traffic and it's harder to separate traffic that is going through many FLs.
Radial engines don't leak oil, they are just marking their territory!
NCB From , joined Dec 1969, posts, RR:
Reply 5, posted (7 years 7 months 2 days 14 hours ago) and read 14859 times:
A light B737-800 carrying little fuel will have a higher optimum cruise altitude than a fully loaded fully-fueled B738. With fuel prices where they are, it is of primary importance to lower fuel consumption as much as possible and in order to achieve that, fly as much as possible and as close as possible to the optimum cruise altitude that could be as high as 39000ft for B738 even if that would involve a longer climb.
If your flight had a light load factor, this would probably be the best explanation.
It is rare for traffic separation at high altitude to force a shorthaul aircraft to fly several thousands of feet above the altitude the pilots requested to fly at. In case of high traffic density you'd probably get stuck with a lower altitude since they wouldn't want you to be criss-crossing the layer of high density traffic twice within a one-hour timeframe.
Another reason that might explain is that there might have been a jetstream at that altitude in the same direction or in reverse direction a bit lower.
For that you would need to check out the met data of that day.
Sandyb123 From UK - Scotland, joined Oct 2007, 1256 posts, RR: 0
Reply 8, posted (7 years 7 months 2 days 7 hours ago) and read 14249 times:
Quoting WunalaYann (Reply 7): You mean it is an astoundingly short hop, regardless of the country?
LOL Yeah, I know what you mean! Although I fly EDI-LCY a bit and it's just on the hour, but the RJ100's don't get anywhere near that level. Having said that I believe their ceiling is quite low at 31,000 foot?
I'm flying on DJ up to Cairns in a couple of weeks so will be interesting to see what happens.
AF1624 From France, joined Jul 2006, 696 posts, RR: 0
Reply 9, posted (7 years 7 months 2 days 6 hours ago) and read 14046 times:
Traffic aside, airliners have a changing optimum cruise altitude. That optimum cruise altitude changes according to how loaded the aircraft is.
Example : 5000 nm flight.
The aircraft will take off quite heavy, because of the fuel load for the voyage, and also the passengers and bags and cargo. Therefore, the aircraft will only be able to go up to a certain altitude, which is its maximum altitude for a given load, and the pilot will choose to fly on an optimum altitude. Again, weather and traffic put aside.
The more heavy the aircraft, the lower the optimum altitude.
Therefore, as the fuel is burned away, and the aircraft gets lighter, it will perform step climbs.
It will fly at FL330 for 2000nm, then FL350 for another 2000nm, then FL370, etc... But that's just an example, of course. The size of the step climb can be different from one flight to the other.
In your situation, the aicraft is already very light, because it's a one hour flight, a short hop. The aicraft can therefore climb to higher altitudes.
Now why would he do that ?
Quite simply because going higher means less fuel burn (couldn't tell ya why though, not an expert).
All the above might not be explained very well, and is certainly not detailed enough, but you get the point...
Jbguller From Australia, joined Jun 2005, 164 posts, RR: 0
Reply 12, posted (7 years 7 months 2 days 4 hours ago) and read 13395 times:
I can't remember a flight between SYD-MEL either way that hasn't been below FL360. The last QF flight I went on, which was last Monday, travelled back to SYD at FL400.... not sure why though. Traffic might have something to do with it, but could it be more to do with jetstreams or turbulence? We encountered a fair bit of turbulence on the last flight?
Av8tor From United States of America, joined Dec 2007, 152 posts, RR: 1
Reply 14, posted (7 years 7 months 2 days 3 hours ago) and read 12419 times:
They also may have been avoiding turbulence. I'll often make the decision to climb to a much higher altitude to give our customers a smooth ride if lower altitudes are getting a lot of turbulence reports. Even a short period with no bumps, so folks can get up and use the lav makes a huge difference in my opinion.
Icna05e From France, joined Feb 2006, 317 posts, RR: 0
Reply 17, posted (7 years 7 months 2 days 1 hour ago) and read 11484 times:
Actually I would say it is the opposite. On such sectors, when you don't climb to FL380-400 it is because you've been told to stop by ATC. There are such things as level capping, when flow management takes a city pair on which they only allow airlines to plan a maximum FL, e.g. 260 on BOD-ORY. We are happy to give a higher clearance if traffic permits, but it won't be that high due to the way the airspace is designed: it implies a lot of coordinations to send the details to other sectors.
Firstly let me congratulate you on choosing the best carrier in Australia, secondly, we at VirginBlue like to provide the best experience possible, be it the highest altitude, the best looking cabin crew, the youngest fleet.... The list goes on and on.. Not to mention the New World Carrier status..
On a technical note though, the previous posts are correct on both points, fuel economy and traffic.
Yes I am biased but I have worked for the opposition and I know who I would rather work for.. It's a no brainer...
Thankyou for choosing DJ as your carrier,,,
No defect too big, no defect too small, nothing in the log --- No defect at all !!
Flycmh2009 From United States of America, joined Jul 2005, 16 posts, RR: 0
Reply 21, posted (7 years 7 months 1 day 23 hours ago) and read 9423 times:
I actually don't think it's that uncommon anymore. Granted private jets are different, but I've seen Gulfstreams and such go as high as FL490 for a flight from Ohio to Florida, about two hours flight time. I think it's all about efficiency.
RSBJ From United States of America, joined Jan 2006, 153 posts, RR: 0
Reply 23, posted (7 years 7 months 1 day 22 hours ago) and read 9163 times:
Just flew GEG-SEA yesterday. Climbed to FL400 for 9 miles (1min 15sec). and started back down. It's just the most fuel-efficient profile. It's fun to watch the oil temps go from 50c below yellow line to about 20 below in about 30 seconds. In case you don't know, the engine oil is cooled by the fuel going into the engine, so less power, less oil cooling.