Flaps30 From United States of America, joined May 2009, 267 posts, RR: 0 Posted (13 years 6 months 2 days ago) and read 4047 times:
I hope some airline pilots who fly frequently within California could answer some questions I have. While on a stopover at SJC, I listened to some clearance deliveries and noticed that some flights going to S. California (Ontario, Burbank, Orange County) had been assigned a cruising altitude of FL410.
With a cruising altitude that high, how long does it take to reach that altitude, and at what point along the flight do you begin the initial descent for, say,
Ontario airport? I suppose Avenal VOR is a little too soon to begin the descent, but it can't be too far past that, otherwise you'd fly right over Ontario airport.
I get the feeling that if the aircraft is relatively heavy, a 1-hour flight with FL410 as the cruising altitude is like driving a car over a mountain- half the trip is spent just climbing to the summit, then the other half is spent descending to the airport.
Cedarjet From United Kingdom, joined May 1999, 7804 posts, RR: 54 Reply 1, posted (13 years 6 months 1 day 22 hours ago) and read 3718 times:
You're right about the trajectory (up and down), in fact when I did a jumpseat ride from Heathrow to Paris CDG we were at cruising altitude (I think about 25,000 ft) for precisely 120 seconds! Then we started down again.
Those FL410 flights you mention are almost certainly bizjets, which have much better performance than big airliners, and commonly cruise at at least 41,000 ft on most flights. I have never heard of any short haul airliner getting that high even on a long flight - maybe 747SPs, 767ERs, 744s et al but no way would a 737-200 get within a mile (literally, almost) of FL410+.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
Mcomess From United States of America, joined Jun 2000, 66 posts, RR: 0 Reply 4, posted (13 years 6 months 1 day 14 hours ago) and read 3613 times:
You're certainly right in that it doesn't make sense, practically or economically for an airline to operate short haul at FL410, even if the aircraft is certified to do so. I've only made it up that high once, and it was on a 767 or 757 (can't remember) due to weather. Although the fuel burn rate is cut drastically, pilots avoid doing this, as often the winds can often get quite high up there- high enough to justify staying at a lower altitude and sacraficing the fuel burn. I have an MD-83 flight manual laying around here where there is actually a guide to determine the benefits/costs of swiching to higher altitudes while inflight. Was there significant weather in your area when you heard this? Nonetheless, I have found that airlines prefer to reroute or request vectors around weather, instead of climbing above it.
Gnomon From , joined Dec 1969, posts, RR: Reply 7, posted (13 years 6 months 1 day 12 hours ago) and read 3599 times:
The 737NG is certified to a service ceiling of FL410, not FL370. In fact, I hear that Southwest routinely operates its 737-700s at FL410 when winds permit to minimize fuel consumption on medium- to long-haul eastbound flights. There's a trip report on the general aviation forum involving a SW -700 cruising from MDW to somewhere on the East Coast at FL410...check it out. It's a well-written post, although I can't remember the author. But, yes, 737NGs are certified to FL410 - and not an inch higher.
Panman From Trinidad and Tobago, joined Aug 1999, 790 posts, RR: 0 Reply 8, posted (13 years 6 months 1 day 7 hours ago) and read 3584 times:
------------------------------- But, yes, 737NGs are certified to FL410 - and not an inch higher.
I don't know where you got that 'not an inch higher' info from.
The main reason why commercial airliners have a service ceiling is mainly to do with cabin pressurisation. Up to the service ceiling the pressure controller is able to maintain a cabin altitude of 8000ft. Above that the altitude of the cabin will climb at the same rate as the aircraft. If the aircraft does go over it's service ceiling then the PSUs will activate (i.e. the oxygen masks will drop for the passengers) and the pilots will have to turn their oxygen supply system to 100% oxygen. [I remember reading somewhere that over 40,000 ft (I think) one of the flight crew must have his oxygen mask on and set to 100% oxygen (in case of cabin depressurisation and incapacitation of the other pilot).]
So though the 737NG may have been certified to a service ceiling of 41,000 ft, it can fly as high as it's engines will enable it to.
Mcomess From United States of America, joined Jun 2000, 66 posts, RR: 0 Reply 11, posted (13 years 6 months 21 hours ago) and read 3530 times:
Service Ceiling and Max Structural Ceiling are two different things.
Service Ceiling is a published figure that the manufacturer recommends to airlines to be used for maximum performance and reliability over several years of service. Max Structural Ceiling, on the other hand, is the maximum altitude you can get the airplane up to before parts of the wings begin to come apart. This is usually not published, as the manufacturers get this data by testing models, making predictions, etc., not by testing an actual aircraft as they do with the Service Ceiling data.
BigGiraffe From United States of America, joined Jan 2000, 257 posts, RR: 0 Reply 12, posted (13 years 6 months 19 hours ago) and read 3514 times:
Max Structural Ceiling? The wings begin to come apart?
Not. There is no such thing as max structural ceiling, and wings do not come apart at high altitude. The airplane ceases to climb when the engines can't put out enough thrust, but that is not a structural issue.
Prebennorholm From Denmark, joined Mar 2000, 6128 posts, RR: 55 Reply 13, posted (13 years 6 months 19 hours ago) and read 3514 times:
Max structural ceiling, where wings fall apart...!
No no, that's wrong, it is Min Strutural Ceiling where everything comes apart. And that's the same altitude for all planes, just about zero feet above ground level - and not one inch lower
Always keep your number of landings equal to your number of take-offs, Preben Norholm
VC-10 From United Kingdom, joined Oct 1999, 3691 posts, RR: 35 Reply 14, posted (13 years 6 months 18 hours ago) and read 3519 times:
Max Structural ceiling, if there is such a term, will be based on the max differential pressure that the fuselage can take. The differential pressure being the difference between the pressurised cabin and the ambient pressure. As a general rule the fuselage will be designed for a max diff of about 9.5 psi. In normal ops max diff is about 8 psi
Pressuristion Controllers will be able to control cabin rate of climb above FL410, the outflow valves will just close more. The limiting factors will be how quickly the engines can pump air into the cabin and the max diff limit.
The 'rubber jungle' will only drop out if the cabin alt exceeds 14 000 ft or if manually selected.
One or two posts have mentioned the fuel saving benefits of flying at high altitude, this has to be balanced against the fuel burnt to get to that altitude
Timz From United States of America, joined Sep 1999, 6632 posts, RR: 7 Reply 15, posted (13 years 6 months 17 hours ago) and read 3511 times:
According to Jane's the 737-200's maximum pressure differential was (and is, we suspect) 7.5 pounds per square inch. Since this is the difference between the standard-day pressures at 8000 ft and FL350, the latter figure becomes the certified ceiling for that model. Although Jane's gives the same figure for the 737-300, I've heard them climbing to FL 370, so apparently Jane's isn't perfect.
Incidentally, the 727 is allowed to climb to FL410 (or maybe 420?), but I've never heard one actually get up there.
Gnomon From , joined Dec 1969, posts, RR: Reply 16, posted (13 years 6 months 11 hours ago) and read 3483 times:
Regarding your post a couple days ago:
I'm perfectly aware that the aircraft can fly far in excess of FL410, structurally. I said it is "certified" to fly to FL410. "Certified" means that, on the various legal documents issued by the manufacturer, FAA, etc., the aircraft is permitted to fly to FL410 in normal passenger-carrying activities. I'm sure that, on occasion, it does actually reach maybe 41,000 feet and 3 inches...
But there are structural components that figure into that altitude, including the maximum pressurization differential, which can exert stresses on the airframe that must be within certain structural limits during normal pax-carrying flights. I'm sure that FL410 would stress the airframe, and I'm sure that FL430 wouldn't, either, but there's a margin of safety built into that number.
AAR90 From United States of America, joined Jan 2000, 3434 posts, RR: 49 Reply 17, posted (13 years 6 months 11 hours ago) and read 3500 times:
Back to the original questions:
>With a cruising altitude that high, how long does it take to reach
Without restrictions (traffic or lack of ATC clearance, etc.) AA's 757s can reach FL410 in about 17-20 minutes for normal N/S Calif. flights. Quickest I've done was 16 minutes from brake release at SNA and that was with derated climb power up to FL310!
>...and at what point along the flight do you begin the initial
>descent for, say, Ontario airport? I suppose Avenal VOR is a
>little too soon to begin the descent, but it can't be too far
>past that, otherwise you'd fly right over Ontario airport.
Prior to Avenal as there are some altitude restrictions on the ONT arrivals.
>I get the feeling that if the aircraft is relatively heavy,
Light, not heavy. This is very short flight for a 757.
Someone else writes:
>Those FL410 flights you mention are almost certainly bizjets,
>which have much better performance than big airliners, and
>commonly cruise at at least 41,000 ft on most flights.
I am constantly restricted in both climb and speed by slow climbing and slow flying business jets. Guess it depends upon what type of bizjet and how it is loaded. OTOH, I've never knowingly been holding up a bizjet.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
Bruce From United States of America, joined May 1999, 5034 posts, RR: 17 Reply 18, posted (13 years 5 months 3 weeks 5 days 19 hours ago) and read 3451 times:
When you talk about altitudes, why do you differentiate between east-west flights and other flights? Is there different altitude restrictions between north-south and east west flights?
and what if your flight is actually a southeast to northwest direction flight - then which rule do you follow?
Bruce Leibowitz - Jackson, MS (KJAN) - Canon 50D/100-400L IS lens
Pacific From Hong Kong, joined Mar 2000, 1044 posts, RR: 0 Reply 19, posted (13 years 5 months 3 weeks 5 days 7 hours ago) and read 3437 times:
I'm under the assumption that cruising speeds are under Mach speeds and not a fixed speed. As the speed of sound is slower at FL410 compared with FL350, if you have to fly longer, would the plane burn more fuel at the end due to the longer flight time?
Embarracing Question- How do you convert knots into Kph or Mph?
Timz From United States of America, joined Sep 1999, 6632 posts, RR: 7 Reply 20, posted (13 years 5 months 3 weeks 4 days 21 hours ago) and read 3431 times:
Since the nautical mile is based on the size of the earth (which is not spherical) there have been various "nautical mile"s in the past, but I think it's now defined as 1852 meters exactly. Since the statute mile is exactly 1609.344 meters that makes the conversion factor knots-to-mph 1.1508.
Yes, most airliners do have a slightly lower airspeed at FL410 than at 350, but the fuel burn per mile is almost always lower, wind etc being equal.
Kaplano1 From , joined Dec 1969, posts, RR: Reply 21, posted (13 years 5 months 3 weeks 2 days 7 hours ago) and read 3414 times:
I always hear A320-200 cruising at FL390 here in Australia (Above the ceiling altitude someone mentioned above). I also have experience FL370 myself in a B737-300 which proves that the service ceiling altitudes are only a guide for an airline. Obviously the more modern an aircraft is the best performance or cruise altitude it would have!
Timz From United States of America, joined Sep 1999, 6632 posts, RR: 7 Reply 22, posted (13 years 5 months 3 weeks 1 day 15 hours ago) and read 3385 times:
Yes, the A320 is allowed FL390, and the 737-300 can go to 370, but I doubt that those ceilings are "only a guide". If some airline did decide to start flying an airliner higher than its certificated ceiling, somebody is supposed to object-- don't ask me who.
I think the Comet was allowed to climb higher than the A320, but most people would consider the A320 the more modern aircraft. Ditto the 727 and 707.
Citation From Sweden, joined Nov 2005, 0 posts, RR: 0 Reply 23, posted (13 years 5 months 2 weeks 6 days 17 hours ago) and read 3377 times:
The FAA Type Certificate Data Sheets list the following Maximum Operating Altitudes in their operating limitations sections:
707 42,000 ft.
727 42,000 ft.
737-100, 200 35,000 ft, unless 37,000 ft is authorized by Flight Manual
737-300, -400, -500 37,000 ft.
737-600, -700, -800 41,000 ft.
747-100 -200, -300, SR, SP, -400 45,100 ft
757-200, -300 42,000 ft
767-200, -300 43,100 ft
777-200, -300 43,100 ft.
Cessna Citations are certified to either 45,000 ft or 51,000 ft depending on the model.
Citation From Sweden, joined Nov 2005, 0 posts, RR: 0 Reply 24, posted (13 years 5 months 2 weeks 6 days 17 hours ago) and read 3373 times:
All of the Boeing aircraft EXCEPT the 737-100 thru -500 have max operating altitudes HIGHER than 41,000 ft. This includes the 707, 727, 737-600 thru-800, all 747s, all 757s, all 767s, and all 777s.
The 757 max operational altitude is 42,000 ft.
25 Kaplano1: What is the highest altitude anyone has seen or heard on their scanner that a Boeing 747-400 has cruised at?
26 B727-200: All B767 operations between MEL-SYD (and v'v) are conducted at FL410 (both AN and QF). This is only a 65 min sector. I have been in the jumpseat thou
27 Skystar: Okay, The Operating Ceilings for aircraft that I am familiar with. B733/4/5 - FL370 B762/3 - FL430 A320/319/321 - FL391 A330/340 - FL410 B744 - FL450
28 Richie: It actually makes a lot of sense taking airplanes higher on short routes than on the long ones (at least in the beginning). Flight Ops manuals show yo
29 Nikonman: I've never heard of planes going to Burbank and Ontario going to 41000. They normally cruise at 29000 up to 33000. I have flown on Alaska's NGs to and
30 Doug_999: Per a friend of mine who was a 737-300/500 pilot, the 300/500 (and I assume 400) is rated at 37,000 feet simply because of how long the emergency oxyg