spiritair97
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US A321 Altitudes Question.

Sat Aug 04, 2012 11:04 pm

My friend was on a US flight from JFK-PHX the other day on an a321 and her flight only got upto 28,000 feet. I noticed that a lot of US Airways' a321s only get upto about FL280 at their cruising altitudes. Why is this? Is there something about the a321s that makes US not want them flying very high?
 
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kc135topboom
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RE: US A321 Altitudes Question.

Sat Aug 04, 2012 11:14 pm

There shouldn't be. The A-321 has enough performance to cruise at more normal altitudes, like FL-350/-370. Staying down at FL-280/-290 may be less crowded than at higher altitudes, but you burn more fuel too. But it may be a weight issue with US loading it up as much as possible.
 
HPRamper
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RE: US A321 Altitudes Question.

Sat Aug 04, 2012 11:20 pm

The flight from JFK-PHX would have headwinds as the prevailing wind pattern is roughly to the northeast. Maybe they were trying to stay under the jet stream?
 
gigneil
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RE: US A321 Altitudes Question.

Sat Aug 04, 2012 11:32 pm

Quoting spiritair97 (Thread starter):
My friend was on a US flight from JFK-PHX the other day on an a321 and her flight only got upto 28,000 feet.

I'm looking at US Airways A321 flights from PHX in general - JFK does seem to be filed at between FL280 and 320 just about every day. That being said, PHX to other East Coast destinations seem to be filed at higher FLs and achieve them almost always.

I am not a pilot - does it have to do with the airways between the two and avoiding other heavily traveled altitudes?

NS
 
spiritair97
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RE: US A321 Altitudes Question.

Sat Aug 04, 2012 11:40 pm

It could have been headwind avoiding. My girlfriend said that it only took about 4 hours.
 
747fan
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 12:07 am

A321's aren't exactly known for having sprightly climb performance. FL280-300 seems rather low, but those airplanes seem to struggle getting into the mid 30's initially when loaded for a transcon flight. ~30 minutes to top of climb is common.
 
cedarjet
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 12:10 am

Must be winds. No reason why the A321 can't get to 35,000. JFK-PHX isn't the furthest the type flies, British Midland / BA fly LHR to Tehran IKA for instance.

Btw the very first 747-100s with the old engines with intake doors around the leading edge of the cowling, were hideously underpowered. Stories abound of United 747-100s on transcend JFK-LAX only getting to an initial cruise altitude of 25,000 feet until they were past Chicago. Wonder how Pan Am ever got them across the Pacific (SFO-HND was nonstop).

Anyway modern jetliners are totally capable and the A321 would have very little trouble making 35,000 ft, especially after an hour or so at (say) 31,000.
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Art at ISP
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 1:56 am

The A-321's used by US Airways have a history of being underpowered. I have been on CLT-LAX flights which started out as low as FL260 due to weight and inability to climb. They have also been notorious for having to make fuel stops on supposed non-stop transcons.

This was using CFM engines on East based aircraft. I am not sure if the newer IAE powered West operated 321s are any better, but I'd imagine they have similar issues. I'd think the current 321's are not well suited for over 2200 mile legs.

That said, they are primarily used for short-mid range high density flights. JFK-PHX used to be 320s and 319's...
 
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 3:05 am

I thought it was a matter of having underpowered engines as well as too much airplane and not enough wing to create the lift to get it above 30,000 feet?

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spiritair97
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 3:39 am

Quoting art at isp (Reply 7):
JFK-PHX used to be 320s and 319's...

Didn't AW also run 757s on the route?

Quoting mattya9 (Reply 8):
I thought it was a matter of having underpowered engines as well as too much airplane and not enough wing to create the lift to get it above 30,000 feet?

When I was tracking her flight, I checked aruond the skies to see other Us a321s flying as high as 38000 feet. (The one I saw was going ORD-CLT, I believe, so it was probably able to fly high on a short flight.) But as for the longer routes, like CLT-LAS, and CLT-PHX, were all around FL280 or 290.
 
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 4:09 am

Quoting spiritair97 (Thread starter):
I noticed that a lot of US Airways' a321s only get upto about FL280 at their cruising altitudes.

On such 4.5hr missions for the A321-200, at departure weights near the MTOW 205,000lbs, the normal cruise profile would be FL300/320/340 as weight is burned off and optimum altitude is bracketed.
The A321NEO with similar thrust (33k) but a slightly better wing, will be a bit more capable, e.g. FL320/340.
 
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zeke
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 4:24 am

Quoting art at isp (Reply 7):
The A-321's used by US Airways have a history of being underpowered. I have been on CLT-LAX flights which started out as low as FL260 due to weight and inability to climb. They have also been notorious for having to make fuel stops on supposed non-stop transcons.

The A321 QRH shows the aircraft is capable of around FL330 at max weight ISA+15.

Many reason for flying lower levels, they include winds, turbulence/ride, technical issues (RVSM), higher levels unavailable without delay due to crossing airways etc. The extra fuel needed to fly something like an A321 at FL280 compared to FL330 is only a matter of around 5% increase in fuel flow, whilst at the same time the lower level gives high TAS getting you there quicker.
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gigneil
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 5:13 am

Quoting 747fan (Reply 5):
A321's aren't exactly known for having sprightly climb performance. FL280-300 seems rather low, but those airplanes seem to struggle getting into the mid 30's initially when loaded for a transcon flight. ~30 minutes to top of climb is common.
Quoting art at isp (Reply 7):
The A-321's used by US Airways have a history of being underpowered. I have been on CLT-LAX flights which started out as low as FL260 due to weight and inability to climb. They have also been notorious for having to make fuel stops on supposed non-stop transcons.
Quoting mattya9 (Reply 8):
I thought it was a matter of having underpowered engines as well as too much airplane and not enough wing to create the lift to get it above 30,000 feet?

Yes. That's already been eliminated as an choice.

US *files* FL280 for a good fraction of their JFK-PHX flights as a final. I don't see a single one filed above FL320. Practically none of their other A321 flights are filed - or fly - that low, even SFO-PHL/CLT, which is much further.

NS
 
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clickhappy
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 5:27 am

Quoting zeke (Reply 11):
Many reason for flying lower levels, they include winds, turbulence/ride, technical issues (RVSM), higher levels unavailable without delay due to crossing airways etc. The extra fuel needed to fly something like an A321 at FL280 compared to FL330 is only a matter of around 5% increase in fuel flow, whilst at the same time the lower level gives high TAS getting you there quicker.

Only 5%? Given the price of fuel, that seems like a huge margin. Quite a hole for the A321 to dig out of, relative to a 739ER.
 
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 6:00 am

Quoting clickhappy (Reply 13):

Airliners fly at non optimum levels all the time for their weight, 2000' below would be something like 2.5%, 4000' below around 5%, and 2000' above around 1.5% more. That is the fuel flow side, if winds and TAS are taken into account, 4000' below might produce the best specific ground range, as it dos today.

Cruising level alone indicates very little, I just plugged in a quick plan over the pair with the route   RBV J230 SAAME J6 HVQ ABB ENL LBL CIM ZUN.EAGUL5 and it shows FL340 would take About 20 minutes longer, lower gives a better SGR.
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AmericanAirFan
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 4:56 pm

Check out this blog. This pilot is a US Airways Airbus A320 series captain. Lots of great stories to read.

http://flightlevel390.blogspot.com/

I recall in some of his blogs they flew at a lower altitude to burn off excess fuel because they can't arrive overweight. The airplanes have a narrow band between being overweight, and not having enough fuel in case they need to divert to an alternate without dipping into their reserve fuel. That is what I gathered from reading the blogs. This was especially crucial on the longer flights such as the JFK-PHX route.



Here is a blog post the Captain did about a flight from ATL-LAS.

http://flightlevel390.blogspot.com/2010/10/excess-fuel.html

This describes perfectly what I said above.

[Edited 2012-08-05 10:00:23]

[Edited 2012-08-05 10:02:07]
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71Zulu
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 6:35 pm

Quoting art at isp (Reply 7):
The A-321's used by US Airways have a history of being underpowered.

The earlier engines were lower powered,

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LoserCruiser
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 6:41 pm

I fly it. The 321's optimum altitudes in the FMS are based on the cost index that the company is using for that particular flight. In many cases, based on whether or not there is turbulence, the optimum altitude doesn't provide an adequate airspeed spread between the high and low buffet margins, therefore we tend to stay lower when being heavy. Needless to say, the performance on the 321 isn't stellar. The maximum takeoff weight is almost 30,000 lbs heavier than the 320 with the same wing.
 
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 6:43 pm

Quoting gigneil (Reply 3):
I am not a pilot - does it have to do with the airways between the two and avoiding other heavily traveled altitudes?

Nah, it's pretty much winds. The A321 can cruise just as fast as any other narrow body jetliner in the sky, so traffic isn't an issue. In considering what route/altitude to file, a pilot's primary concerns beyond his a/c's capabilities are wind and weather. Distance and pref routes come second, and traffic doesn't really enter into it at all. You're just not going to run into "traffic jams" on airways (though vectors are never out of the realm of possibility on well-traveled routes). The slow ups will be caused by the airport itself, and thus be unavoidable no matter what your route/altitude.

[Edited 2012-08-05 11:44:49]
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RE: US A321 Altitudes Question.

Sun Aug 05, 2012 7:03 pm

Quoting clickhappy (Reply 13):
Quoting zeke (Reply 11):
Many reason for flying lower levels, they include winds, turbulence/ride, technical issues (RVSM), higher levels unavailable without delay due to crossing airways etc. The extra fuel needed to fly something like an A321 at FL280 compared to FL330 is only a matter of around 5% increase in fuel flow, whilst at the same time the lower level gives high TAS getting you there quicker.

Only 5%? Given the price of fuel, that seems like a huge margin. Quite a hole for the A321 to dig out of, relative to a 739ER.

It's also a matter of the cost index. If the fuel to get you to your destination is 5% more, but due to the faster speed and the possibility of cramping in another rotation for the day, you've made your 5% increase in fuel worth quite a bit. Also, the factor of crew salary is very big these days. If you fly slower and burn less that might make your fuelcounters happy, but your staff might go over time & duty, making it a requirement to carry another crew or get the one in a hotel overnight etc etc.
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