Just wondering if anyone has more info than I can find in regs/certifications with regards to service ceilings. As far as I can tell, the highest bizjet ceilings seem to be FL510, is there anything higher?

Cheers

510? Wow, what business jets go that high? I've seen flight level 470 numerous times, not 510.

JamesCousins wrote:

510? Wow, what business jets go that high? I've seen flight level 470 numerous times, not 510.

From top of my head, Cessna Citation X and Learjet 70/75. There are probably a few other.

For Service Ceilings in general - for non-military plane I would say Concorde at FL600 would probably be the highest.

Military Jet I want to say it's SR-71 (FL850), exact service ceiling for those are not always available, though.

The Gulfstreams and Globals are certified to F510, as are the Lears since the 31A. On the Globals, F490 and F510 are reachable at light weights (last hour or so of cruise), but rarely optimum levels.

GF

Just cus an airplane can get to 510 doesn’t mean it’s optimal. Ask those pinnacle pilots about going to 410 in their RJ

Do one of the pilots need to be on O2 the entire flight at that altitude for FAA reasons or are they under different regs than commercial aircraft?

32andBelow wrote:

Just cus an airplane can get to 510 doesn’t mean it’s optimal. Ask those pinnacle pilots about going to 410 in their RJ

Don’t confuse “suboptimal” with what happened to Pinnacle 3701. That altitude could have very well been the best altitude for that day if they would have followed standard operating procedure and shown good airmenship that day.

32andBelow wrote:

Just cus an airplane can get to 510 doesn’t mean it’s optimal. Ask those pinnacle pilots about going to 410 in their RJ

I am mad at myself for laughing.

Substantive question, is 510 better in terms of weather?

Flighty wrote:

32andBelow wrote:

Just cus an airplane can get to 510 doesn’t mean it’s optimal. Ask those pinnacle pilots about going to 410 in their RJ

I am mad at myself for laughing.

Substantive question, is 510 better in terms of weather?

FL510 can be "better in terms of weather," yes. I'd suggest that the more frequent justification for a very high altitude cruise is to get about the jetstream, cruising in light headwinds with lower fuel burn (due to the lack of headwinds and the low fuel flow rate).

[threeid][/threeid]The Lear 45/75 do pretty well at F470 and above. The Global’s highest optimum level (best ANMPP of fuel) is usually F470 with weights under about 63,000. F510 is achieveable at M.82 and have reasonable buffet boundaries, just not very efficient. F450 will get one above je5 streams, especially in winter where they seem lower. F450 or F470 only helps some in getting over weather in the tropics.

Yes, for Part 91, 91.211 requires one pilot to be on O2 at all times above F410. Clever interpretation of 121/135 rules based on cabin altitude, not so much.

GF

zakuivcustom wrote:

.....
Military Jet I want to say it's SR-71 (FL850), exact service ceiling for those are not always available, though.

Maybe I'm being a bit too anal here, but airspace above FL600 reverts to Class E which doesn't require reporting as 'Flight Level' but uses altitude. Of course anybody up there is either military or civilian research/test/evaluation.

The highest altitude for subsonic transport airplanes, to be certified according the current FAA rules is FL510.


See : http://rgl.faa.gov/Regulatory_and_Guida ... enDocument

GalaxyFlyer wrote:

Yes, for Part 91, 91.211 requires one pilot to be on O2 at all times above F410. Clever interpretation of 121/135 rules based on cabin altitude, not so much.

Seriously? We fly EASA-Ops. At flight times >1:30h always above FL410 and never ever use O2.

Yes, 91.211 says one pilot must be on O2 at all times the aircraft altitude is above F410. The commercial regs reference cabin altitude above 10,000’. I was on the NBAA committee trying get align with the commercial rule or ICAO SARP or anything to get relief. It requires a NPRM change and, with the CAMI strongly opposed, it ain’t happening. It doesn’t concern the airlines, so the FAA GA people couldn’t care less.

It’s unfortunately widely ignored, which is a normalization of deviation. Heck, the FAA crews admit they don’t comply. EU SAFA checks have been known to check O2 quantity to verify crew use on a TATL crossing.

GF

747classic wrote:

The highest altitude for subsonic transport airplanes, to be certified according the current FAA rules is FL510.


See : http://rgl.faa.gov/Regulatory_and_Guida ... enDocument

For you all more knowledgeable than I, Why? I have seen discussed many factors for high FL's like time to decent to 10,000, time on O2, time of useful conciousness at that high FL, etc...

Or is it that at the time of the regulation aircraft couldn't reach that high, even now it's not a regular occurance for the majority of jets out there.

packcheer wrote:

747classic wrote:

The highest altitude for subsonic transport airplanes, to be certified according the current FAA rules is FL510.


See : http://rgl.faa.gov/Regulatory_and_Guida ... enDocument

For you all more knowledgeable than I, Why? I have seen discussed many factors for high FL's like time to decent to 10,000, time on O2, time of useful conciousness at that high FL, etc...

Or is it that at the time of the regulation aircraft couldn't reach that high, even now it's not a regular occurance for the majority of jets out there.

If operation above FL510 is required new certification standards need to be developed.

"It must be noted that widespread operation of transport category airplanes at altitudes greater than 51,000 feet is not currently envisioned.
A major factor in an approval for operation up to 51,000 feet is an emergency descent during a decompression, which must be shown to result in a maximum cabin altitude of no more than 40,000 feet. Accordingly, the changes adopted in this amendment have been developed to provide adequate standards for safe operation of such airplanes up to 51,000 feet.
Should an applicant seek approval to operate a transport category airplane above that altitude, additional standards may be needed for safe operation. If so, appropriate special conditions would be adoptive to require compliance with those standards"

When I was at Global (certified to FL510) type training at Montreal there was an Australian dude in the class whose boss was downsizing from BBJ to Global because the BBJ couldn’t get above the nasty weather crossing the equator. No prudent pilot would climb to FL510 to top weather but higher is generally better.

I'm no pilot, so I'm curious about the benefits of flying that high? From what I'm reading it's only optimal for short periods of time? I'm guessing weather considerations?

Altitude can be useful topping weather including t’storms. At F470, while the weather can get higher, that level does put above 90% of it. Many times one can top the cirrus for a better visual picture on the weather. In the Global, on a short leg like 3-4 hours, F430-F470 is useable for the entire flight, so topping weather and reduced fuel burn. Weather includes headwinds, too. It just more capability.

In areas of non-radar control (Africa, Oceanic regions, for example) one is above just about all traffic, so adds a bit of security.

GF

GalaxyFlyer wrote:

Altitude can be useful topping weather including t’storms. At F470, while the weather can get higher, that level does put above 90% of it. Many times one can top the cirrus for a better visual picture on the weather. In the Global, on a short leg like 3-4 hours, F430-F470 is useable for the entire flight, so topping weather and reduced fuel burn. Weather includes headwinds, too. It just more capability.

In areas of non-radar control (Africa, Oceanic regions, for example) one is above just about all traffic, so adds a bit of security.

GF

Thanks for humoring me on this!

The Concorde was capable of cruise altitudes above FL 600 and reached altitudes of over 67000
feet during testing (and Mach 2.2)

This extra altitude capability would have been useful to lower its prodigious fuel burn a bit more but as stated FL 600 had to be the limit
in order to comply with emergency decompression descent times

Max Q wrote:

The Concorde was capable of cruise altitudes above FL 600 and reached altitudes of over 67000
feet during testing (and Mach 2.2)

This extra altitude capability would have been useful to lower its prodigious fuel burn a bit more but as stated FL 600 had to be the limit
in order to comply with emergency decompression descent times

Would this really have been a significant reduction in fuel burn? After all, the air already is so thin at FL600, I wouldn't think it makes much of a difference, only a few hectopascal. Where would the additional saving come from?

Regards,

Kind of a cool story..... so I’m an enroute controller in the U.S. for 12 years now. To date I have had one aircraft that was cruising along at FL510. I forget which type, but it was one of the fancy biz-jets. Only one higher I have worked was a U2 who checked in “above fl600”, but that doesn’t count for this threads sake.
So the guy I had at FL510 was getting fairly close to the destination so it was time to start him down. Ironically enough he had crossing traffic who was cruising at FL470, so all I had available at the time was FL490. “N1234 descend and maintain flight level four miner zero” lol. Someone else on the freq keys up and says hey center, did you just descend someone to FL490?, I say affirmative, and he replies saying....”good frief, what Altitude was he at?” Lol

It will be interesting how this is approached. For example, the MC-21 has far lower wing loading and a higher cruise speed than the A320. This generates a higher optimum cruise altitude. Combined with a lower weight, it will be interesting to see the comparative flight profile.

CFRP and later GFRP wings will shift up cruise altitudes. Look at the MD-90 vs. A320. The high wing loading and thus lower cruise altitude doomed the MD-90. For the higher cruise fuel burn hit range too much.

747classic wrote:

packcheer wrote:

747classic wrote:

The highest altitude for subsonic transport airplanes, to be certified according the current FAA rules is FL510.


See : http://rgl.faa.gov/Regulatory_and_Guida ... enDocument

For you all more knowledgeable than I, Why? I have seen discussed many factors for high FL's like time to decent to 10,000, time on O2, time of useful conciousness at that high FL, etc...

Or is it that at the time of the regulation aircraft couldn't reach that high, even now it's not a regular occurance for the majority of jets out there.

If operation above FL510 is required new certification standards need to be developed.

"It must be noted that widespread operation of transport category airplanes at altitudes greater than 51,000 feet is not currently envisioned.
A major factor in an approval for operation up to 51,000 feet is an emergency descent during a decompression, which must be shown to result in a maximum cabin altitude of no more than 40,000 feet. Accordingly, the changes adopted in this amendment have been developed to provide adequate standards for safe operation of such airplanes up to 51,000 feet.
Should an applicant seek approval to operate a transport category airplane above that altitude, additional standards may be needed for safe operation. If so, appropriate special conditions would be adoptive to require compliance with those standards"

There are decompression reasons that need to be addressed for even higher altitudes. Military aircraft put crew in pressure suits which overcomes concerns. How did Concorde handle it?

e.g., sudden decompression can cause one to pass out, even on oxygen. So FL510 seems reasonable as a limit.

Lightsaber

kiowa wrote:

Do one of the pilots need to be on O2 the entire flight at that altitude for FAA reasons or are they under different regs than commercial aircraft?

At my airline the regulations say we must wear oxygen masks above 40000 feet. But we have a loophole: Quick donning masks mean the requirement is waived. Granted, the aircraft maxes out at 43100 feet.

lightsaber wrote:

There are decompression reasons that need to be addressed for even higher altitudes. Military aircraft put crew in pressure suits which overcomes concerns. How did Concorde handle it?

Lightsaber

Very very small windows.

At FL430 and above, do you really count for the curvature of the earth for flight planning and descent purpose?

benbeny wrote:

At FL430 and above, do you really count for the curvature of the earth for flight planning and descent purpose?

No. Who gave you that idea?

Semaex wrote:

benbeny wrote:

At FL430 and above, do you really count for the curvature of the earth for flight planning and descent purpose?

No. Who gave you that idea?

Just curiosity, I don't know whether earth curvature plays a role or not

benbeny wrote:

Semaex wrote:

benbeny wrote:

At FL430 and above, do you really count for the curvature of the earth for flight planning and descent purpose?

No. Who gave you that idea?

Just curiosity, I don't know whether earth curvature plays a role or not

43000 feet is only 7 nautical miles.

Having said that, FLS approaches on Airbus give a slight discrepancy compared to ILS. Geometric altitude in the FLS accounts for curvature, while beam guided altitude from an ILS does not.

trnswrld wrote:

Kind of a cool story..... so I’m an enroute controller in the U.S. for 12 years now. To date I have had one aircraft that was cruising along at FL510. I forget which type, but it was one of the fancy biz-jets. Only one higher I have worked was a U2 who checked in “above fl600”, but that doesn’t count for this threads sake.
So the guy I had at FL510 was getting fairly close to the destination so it was time to start him down. Ironically enough he had crossing traffic who was cruising at FL470, so all I had available at the time was FL490. “N1234 descend and maintain flight level four miner zero” lol. Someone else on the freq keys up and says hey center, did you just descend someone to FL490?, I say affirmative, and he replies saying....”good frief, what Altitude was he at?” Lol

Houston Center?

I had something similar happen there and ended up at FL490 about 60-70 miles from a crossing restriction after a slow descent from 510. When we got the descent from 490 I opened the speedbrakes and the airplane started shaking like a wet dog. No air for them to grab that high I guess. Everything became normal again passing through 450.

trnswrld wrote:

Kind of a cool story..... so I’m an enroute controller in the U.S. for 12 years now. To date I have had one aircraft that was cruising along at FL510. I forget which type, but it was one of the fancy biz-jets. Only one higher I have worked was a U2 who checked in “above fl600”, but that doesn’t count for this threads sake.
So the guy I had at FL510 was getting fairly close to the destination so it was time to start him down. Ironically enough he had crossing traffic who was cruising at FL470, so all I had available at the time was FL490. “N1234 descend and maintain flight level four miner zero” lol. Someone else on the freq keys up and says hey center, did you just descend someone to FL490?, I say affirmative, and he replies saying....”good frief, what Altitude was he at?” Lol

Houston Center?

I had something similar happen there and ended up at FL490 about 60-70 miles from a crossing restriction after a slow descent from 510. When we got the descent from 490 I opened the speedbrakes and the airplane started shaking like a wet dog. No air for them to grab that high I guess. Everything became normal again passing through 450.

Sure you weren’t at low speed buffet? Rip open the boards on a Global up there and the speed went away quickly.

GF

GalaxyFlyer wrote:

Sure you weren’t at low speed buffet? Rip open the boards on a Global up there and the speed went away quickly.

GF

Nope. It's been a while and I don't remember the numbers we had but we had plenty of speed.

The Citation X has a ton of buffer between stall and overspeed up high.