What is the highest altitude commercial aircraft fly?

Question

What is the highest altitude commercial aircraft generally fly? I know I have been in planes that flew between 25,000 and 35,000 ft. It seems that some international flights are on the higher end like 32,000 to 35,000 ft. Does anyone know if there are any regulations on what the highest altitudes allowed are? Are max altitudes any different for aircraft in Canada?

Answer 1

The max is 45,000 feet to remain under ATC. The maximum type varies but the 737-700 is 41,000 but normally cruises around 35,000 fore opitimal effeciency. We fly Gulfstreems all the time above 45,000. The main reason is you don't follow ATC and Vectors. Once you are cleared above 45 you can fly point to point anywhere you want. The G 5 is certified at 51,000. The absolute max regardless of type is 60,000 without special permission from the FAA (and proof you own an SR-71).

Answer 2

The combination of altitude and cruise speed that an aircraft is capable of attaining is a function of how heavy the aircraft is (how much fuel, cargo, and passengers) as well as the atmospheric conditions (temperature, pressure altitude, etc.).

The engines are no more susceptible to flame out at higher altitudes because the fuel scheduling is electronic and extremely reliable. It also doesn't put additional stress on the airplane to go higher, it's just that an airplane will eventually reach an absolute ceiling in which it simply can't fly any higher. To fly at a maximum altitude, the pilots will determine the highest altitude that they can currently fly (or the altitude in which a minimum rate of climb, such as 500'/minute, can be attained) based on their weight and the atmospheric conditions. Usually, they don't choose the absolute maximum altitude but rather, the maximum altitude that they can attain a specfic climb rate. They will then choose the next lowest altitude as required by ATC (in other words, ATC isn't going to let you fly at 38,418 feet, however, if going westbound, they will let you fly at 38,000 feet, so this is the next lowest altitude compatible with ATC). Pilots will analyze their current conditions before requesting a climb. Current conditions are constantly changing because the airplane loses weight as it flies along and burns fuel and the temperature can vary substantially over a defined geographic area. Aircraft pressurization systems are designed to provide a cabin differential pressure that reaches a maximum limit. Once the maximum differential pressure is reached then as the plane climbs higher and higher the air pressure inside the cabin will also continue to climb at the differential rate. But that doesn't hurt the airframe.

There have been times when I have been flying along at high altitude and suddenly the air will warm up a little. The throttles can be advanced up to a point, but if greater thrust is required than what the engines are capable of producing, the airplane will slow down. If the airplane slows down too much, a descent to a lower altitude may be necessary. If you stay in the same pocket of warm air for an extended period of time then you will continue burning down fuel and eventually, the airplane will speed back up to its original speed. Either that or again, you can decrease altitude, or find a colder air (which really isn't practical).

As a pilot, the highest I have flown is 43,000 feet.

Answer 3

Highest Flying Aircraft

Answer 4

Most commercial jetliners cruise somewhere between 30,000 and 45,000 feet above mean sea level. At higher speeds and altitudes, there isn't enough oxygen in the air to continuously burn the jet fuel required to stay up there. Engines designed to work very well that high, have serious limitations when they are operated closer to the surface.

The main exception was the Concorde which was designed to fly at a higher altitude (and hence lower wind resistance) at around 45,000ft. Although many jets could fly at higher altitudes, they are usually certified to an altitude giving a wide safety margin. For example the new generation Boeing 737 is certified to 41,000ft.

Aloha

Answer 5

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RE:
What is the highest altitude commercial aircraft fly?
What is the highest altitude commercial aircraft generally fly? I know I have been in planes that flew between 25,000 and 35,000 ft. It seems that some international flights are on the higher end like 32,000 to 35,000 ft. Does anyone know if there are any regulations on what the highest...

Answer 6

It's not so much regulations as it is physics...about 40,000 feet, there's just not enough air for the engines to work well, and the airframes aren't designed to the lower pressure at altitudes over 45,000 feet -- so those are hard limits, not regulations.
I've been on a LA-Tokyo flight where the jetstream was hitting us hard, so we went up to 40,000 feet and the pilot told us it was as high as he was allowed to go for safety reasons.

No different physics for Canada, same problems :)

Answer 7

You are correct on where they fly "generally".
The regulation in place (In the US) is operation in Class "A" airspace which has an upper limit of 60,000' MSL above that you need special permission from the FAA. There is talk about creating a new class of airspace to accomadate the likes of Burt Ratan's SpaceShipOne
built for Private "space travel"