Cedarjet From United Kingdom, joined May 1999, 8395 posts, RR: 54
Reply 1, posted (9 years 8 months 1 week 6 days 21 hours ago) and read 6420 times:
Even on the longest of flights, they don't tend to go any higher than 39,000 feet. If the aircraft is right on it's max takeoff weight, they might spend more of the flight lower, ie 28,000 feet initial cruise, then a step climb as fuel burns off. I remember early 747-100s used to start the cruise at 25,000 feet (and people say the A340 is underpowered! haha!). The highest I've ever flown on a conventional airliner is 41,000 feet, but not necessarily on the longest flights. I remember hitting FL410 flying from London to Charlotte NC on a 767-200. I don't remember going above FL390 on any of the proper-longhaul flights I regularly do (eg LAX-SYD, NRT-LHR et al).
The exception is the 747SP. I spoke to the cockpit crew of the Iranair SP that took many of us a.netters around Cologne last year, and the captain said the 747SP is the most capable aircraft ever built - range, endurance, max altitude, speed etc. They were ferrying the SP empty back to Teheran, and had filed a cruise altitude of 43,000 feet. No other airliner can do that, no way.
fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
Julesmusician From , joined Dec 1969, posts, RR:
Reply 6, posted (9 years 8 months 1 week 6 days 17 hours ago) and read 6219 times:
I remember a flight I did on the flight deck of a 757. I specifically requested whether in the flight from London Heathrow to Edinburgh all of 1hr or so we could top 40,000. The captain said he would give it a go but it would be close. As we tagged the autopilot up to 40,000 we touched it for about two minutes before starting the descent. Probably cost BA considerable more fuel, but oil was cheaper then
Mr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 21
Reply 7, posted (9 years 8 months 1 week 6 days 10 hours ago) and read 6175 times:
It's possible for airliners to cruise at very altittudes if theya re relatively light, usually close to the end of the trip nearing the destination. I've also seen on flight trackers SQ B747s crossing the atlantic at FL 390 climibng to FL 430 when closing in on the eastern US coast.
Star_world From Ireland, joined Jun 2001, 1234 posts, RR: 0
Reply 8, posted (9 years 8 months 1 week 6 days 10 hours ago) and read 6172 times:
Quoting Julesmusician (Reply 6): I remember a flight I did on the flight deck of a 757. I specifically requested whether in the flight from London Heathrow to Edinburgh all of 1hr or so we could top 40,000. The captain said he would give it a go but it would be close. As we tagged the autopilot up to 40,000 we touched it for about two minutes before starting the descent. Probably cost BA considerable more fuel, but oil was cheaper then Smile
Hmmm I presume this was in a BA simulator rather than a real aircraft. BA captains don't just "give it a go" to reach altitudes that someone in the jumpseat requests....!
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66
Reply 10, posted (9 years 8 months 1 week 4 days 17 hours ago) and read 6025 times:
Quoting Doug_Or (Reply 9): why would local baro settings matter above transition alt?
Well, as I indicated I consider it a little far-fetched but a possible problem. Because local baro settings are considered to affect the pressures at heights above the surface* On the other hand the type certificate limitation of 43,100 feet is expressed in altitude, not flight level.
So, presumablly when flying at FL430 if the air mass pressure in the region was very high, you might be higher than 43,100 feet absolute while indicating an even 43. It would not create a collision hazard because all aircraft would be flying with the 1013MB reference, but you might be flying at an absolute height greater than permitted by the type certificate.
Again, unlikely to cause you a problem, but theoretically against the rules.
* See the AIM, Section 7-2-2 regarding Lowest Usable Flight Levels with local altimeter settings lower than 29.93"hg (1013.2MB)
Happiness is not seeing another trite Ste. Maarten photo all week long.
Capt_smith From United States of America, joined May 2000, 65 posts, RR: 0
Reply 12, posted (9 years 8 months 1 week 4 days 6 hours ago) and read 5953 times:
I was playing around with a GPS unit while flying WN from CMH to TPA and I swear the altitude I saw displayed after we reached cruise, was FL410. This varied a little, but stayed in that range for most of the flight. The funny thing is, I THOUGHT the capt. had mentioned reaching 39,000 f t. all the while I was seeing 41,000. Surely my GPS could not have been off that much. Can anyone explain what might have been going on?