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Very High Flight - Why?  
User currently offlineSandyb123 From UK - Scotland, joined Oct 2007, 1039 posts, RR: 0
Posted (5 years 6 months 2 weeks 1 day 12 hours ago) and read 14491 times:
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Hi guys,

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?

Sandyb123


DC3, 727, 737, 744, 753, 777, A32X, A345, A388, ERJ145, E190, BaE146, D328, ATR72, Q400
36 replies: All unread, showing first 25:
 
User currently onlineQantasA333 From Australia, joined Jan 2007, 537 posts, RR: 4
Reply 1, posted (5 years 6 months 2 weeks 1 day 12 hours ago) and read 14465 times:

It happens a lot over here. 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.

There is a flight between MEL and SYD every half hour on both airlines, so could have been a traffic problem, which caused you to go up that high.


User currently offlineFlyDreamliner From United States of America, joined Jan 2006, 2759 posts, RR: 15
Reply 2, posted (5 years 6 months 2 weeks 1 day 11 hours ago) and read 14335 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"
User currently offlinePnwtraveler From Canada, joined Jun 2007, 2199 posts, RR: 12
Reply 3, posted (5 years 6 months 2 weeks 1 day 10 hours ago) and read 14271 times:

Could also be winds. They tend to go in different directions at different altitudes. The winds that high may have been more tail winds so would save a lot f fuel even on a short hop.

User currently offlineYXD172 From Canada, joined Feb 2008, 449 posts, RR: 0
Reply 4, posted (5 years 6 months 2 weeks 1 day 10 hours ago) and read 14239 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.

Jon



Radial engines don't leak oil, they are just marking their territory!
User currently offlineNCB From , joined Dec 1969, posts, RR:
Reply 5, posted (5 years 6 months 2 weeks 1 day 10 hours ago) and read 14198 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.


User currently offlineGigneil From United States of America, joined Nov 2002, 16345 posts, RR: 86
Reply 6, posted (5 years 6 months 2 weeks 1 day 9 hours ago) and read 14053 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.

In my experience, international flights are almost always much lower.

At any rate, WN flies their 737-700s at 41,000 all the time. If you're light, there's all sorts of benefits to flying up there - weather, avoid less capable traffic, etc.

NS


User currently offlineWunalaYann From Australia, joined Mar 2005, 2839 posts, RR: 26
Reply 7, posted (5 years 6 months 2 weeks 1 day 8 hours ago) and read 13918 times:



Quoting Sandyb123 (Thread starter):
It's relatively short hop (at least in Australian terms)

You mean it is an astoundingly short hop, regardless of the country?  Smile

Mind you, there are tons of SYD-CBR flights so I guess these take the cake as far as mindless transport system design goes...  Wink


User currently offlineSandyb123 From UK - Scotland, joined Oct 2007, 1039 posts, RR: 0
Reply 8, posted (5 years 6 months 2 weeks 1 day 3 hours ago) and read 13588 times:
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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.

Thanks for all your replies!

Sandyb123



DC3, 727, 737, 744, 753, 777, A32X, A345, A388, ERJ145, E190, BaE146, D328, ATR72, Q400
User currently offlineAF1624 From France, joined Jul 2006, 644 posts, RR: 0
Reply 9, posted (5 years 6 months 2 weeks 1 day 2 hours ago) and read 13385 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...



Cheers
User currently offlineAntonovA330 From Switzerland, joined Jul 2007, 327 posts, RR: 0
Reply 10, posted (5 years 6 months 2 weeks 1 day 2 hours ago) and read 13347 times:

I was once on a SR A319 from ZRH to ARN. We were cruising on FL390. Quite high I thought as well.


Good day to you sir! Please turn left, your seat is in the first row.
User currently offlineDynamicsguy From Australia, joined Jul 2008, 851 posts, RR: 9
Reply 11, posted (5 years 6 months 2 weeks 1 day ago) and read 12735 times:



Quoting WunalaYann (Reply 7):
You mean it is an astoundingly short hop, regardless of the country?

Astoundingly short if the population density justified the cost of high speed rail as in much of Europe. Certainly preferable to the 10 hours or more on the road or on rail.

I agree on SYD-CBR though. Door-door there's no advantage in flying to Canberra over driving yourself or getting on a bus or train.


User currently offlineJbguller From Australia, joined Jun 2005, 164 posts, RR: 0
Reply 12, posted (5 years 6 months 2 weeks 1 day ago) and read 12734 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?

User currently onlineTristarSteve From Sweden, joined Nov 2005, 3930 posts, RR: 34
Reply 13, posted (5 years 6 months 2 weeks 23 hours ago) and read 12109 times:

If ATC allows the most fuel efficient way to fly a short sector is to climb to TOD and then descend at idle. Any level cruise period costs more fuel.
But on most short hops ATC stops this.


User currently offlineAv8tor From United States of America, joined Dec 2007, 141 posts, RR: 0
Reply 14, posted (5 years 6 months 2 weeks 23 hours ago) and read 11758 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.

User currently offlineSASDC8 From Norway, joined Mar 2006, 699 posts, RR: 1
Reply 15, posted (5 years 6 months 2 weeks 22 hours ago) and read 11263 times:
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Just did OSL - BOO, a 1 hour 15 min flight, on Thursday and we crused at 37000 feet. I seems like the norm these days, at least on SK, to cruice at 37-38 or even 39000 feet.

Cheers
Stein



2-3-2 is NOT a premium configuration
User currently offlineDALCE From Netherlands, joined Feb 2007, 1661 posts, RR: 7
Reply 16, posted (5 years 6 months 2 weeks 22 hours ago) and read 11121 times:



Quoting SASDC8 (Reply 15):
Just did OSL - BOO, a 1 hour 15 min flight, on Thursday and we crused at 37000 feet. I seems like the norm these days, at least on SK, to cruice at 37-38 or even 39000 feet.

Had the same on a SK 737-600 last year flying from OSL to AMS on FL400.
I know it for sure since I was Jumpseating in the frontoffice  Smile
This flight is also around 1.15hr - 1.30hrs.



flown on : F50,F70,CR1,CR2,CR9,E75,143,AR8,AR1,733,735,736,73G,738,753,744,319,320,321,333,AB6.
User currently offlineIcna05e From France, joined Feb 2006, 296 posts, RR: 0
Reply 17, posted (5 years 6 months 2 weeks 21 hours ago) and read 10823 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.

User currently offlineCRJ900 From Norway, joined Jun 2004, 2152 posts, RR: 1
Reply 18, posted (5 years 6 months 2 weeks 20 hours ago) and read 9910 times:
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I flew OSL-MUC with LH CRJ900 recently, and most of the flight was at 39,000 feet, according to the pilot. The flight was 1h 55min. Pretty impressive for such a small aircraft.


Come, fly the prevailing winds with me
User currently offlineCumulus From United Kingdom, joined Aug 2006, 1402 posts, RR: 1
Reply 19, posted (5 years 6 months 2 weeks 20 hours ago) and read 9910 times:

Maybe to give a better view?!!!


What Goes Up Must Come Down, Hopefully In One Piece!
User currently offlineOzTech From Australia, joined Feb 2007, 161 posts, RR: 0
Reply 20, posted (5 years 6 months 2 weeks 20 hours ago) and read 9662 times:



Quoting Sandyb123 (Thread starter):
I recently took a Virgin Blue flight out of Melbourne for Sydney

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 !!
User currently offlineFlycmh2009 From United States of America, joined Jul 2005, 16 posts, RR: 0
Reply 21, posted (5 years 6 months 2 weeks 19 hours ago) and read 8762 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.

User currently offlineTimz From United States of America, joined Sep 1999, 6707 posts, RR: 7
Reply 22, posted (5 years 6 months 2 weeks 18 hours ago) and read 8524 times:

If you look for OAK-LAX or SFO-LAX flightplans at http://flightaware.com/statistics/ifr-route/ you'll see some 737s climb to 41000 ft on those trips, which are rather shorter than MEL-SYD.

User currently offlineRSBJ From United States of America, joined Jan 2006, 152 posts, RR: 0
Reply 23, posted (5 years 6 months 2 weeks 18 hours ago) and read 8502 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.


I fly really fast and take a lot of chances.
User currently offlineBurnsie28 From United States of America, joined Aug 2004, 7503 posts, RR: 8
Reply 24, posted (5 years 6 months 2 weeks 18 hours ago) and read 8194 times:

It might not always be traffic, often times flying GFK-MSP where there is little traffic (if any but us) we have flown at 35-40K for a 285 mile journey.


"Some People Just Know How To Fly"- Best slogan ever, RIP NW 1926-2009
25 WestJetYQQ : Whenever I fly on WestJet between Comox and Calgary (usually 70-80 minutes, so a pretty quick flight) on their 737NGs they often cruise at 41,000' on
26 Post contains links Hawkercamm : The aerodynamic efficiency of transonic commercial airliners is directly proportional to the aircraft "angle of attack" to the oncoming air. At some
27 HawkerCamm : 40,400ft is not a normal level cruise Flight Level which are usually every whole 1000ft's. Therefore you may have been climbing or desending to an as
28 Boeingluvr : Very often traffic in Canada fly at FL410 which is the top service altitude for 73G's.
29 Post contains links Acey559 : Even the RJs can get pretty high. We have a couple CR7s running MLI-ATL and they usually get pretty high. This flight from yesterday went up to FL370,
30 Spacecadet : They usually start out that way, but most will do a staggered climb. It all depends on how much fuel they're carrying. A fully loaded 747 is not goin
31 NZaholic : Back in the days of 757's on BA shuttles LHR to Scotland (EDI and GLA, both easily less than 1 hr blocktime with good routeing and no holding) it was
32 Myt332 : Funny, I did SYD-BNE once in a DJ B738 and we went straight up to FL410. It was rather interesting. I did the MAN-LHR route as a passenger countless
33 Jetterrosie : In any case it's beautiful flying at that altitude where the sky turns a nice deep blue due to the thinner atmosphere (the reason it is also more fuel
34 Spacecadet : The thinner atmosphere reduces drag but also reduces lift. So it's not always the case that just flying higher is more fuel efficient. That's why air
35 Speedbird128 : Domestic or international flight is totally irrelevant... It's all about winds and aircraft weight... Perhaps traffic at a push if for instance F380
36 Hmmmm... : This is the answer in a nutshell. For any particular flying weight, the airplane will have an optimum altitude. With a lightly loaded airplane, it pa
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