CaptainT38
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Question About Max Operating Ceiling?

Thu Mar 31, 2005 10:44 pm

Does anyone know why the Max operating ceiling of most Corporate Aircraft is 51,000ft? I know above that there are some serious risks involved if lost of cabin pressure or any other type of emergency. Just have never really figured out why 51,000?
 
Lemmy
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 7:42 am

51,000ft is way up there. Which bizjets are certified to fly that high?

I'm not sure how long an emergency descent from FL510 would take, but it's got to feel like forever when the wind is whistling through the cockpit and you've pooped your pants due to a combination of fear and pressure differential.

Question about emergency descent procedures: Are they generally flown manually? I ask because, considering the very short time you'd have to stay conscious if O2 isn't working right, wouldn't it be a good idea to dial 12,000 ft into the autopilot, set your speed at VMO/MMO, extend the spoilers, and then hit FLCH? That way, if you got a little bit loopy on the way down, the autopilot would fly the plane.
I am a patient boy ...
 
troubleshooter
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 7:54 am

Please someone correct me, if I´m wrong, but isn´t there a procedure that one cockpit member must wear the oxygen mask above a certain FL. This will reduce the risk for both pilots of getting unconscious if there is a rapid decompression. The time of usefull consciousness at this altitude is reduced to a few seconds!

I heard a story about a Learjet with a rapid decompression at a very high altitude. Both pilots and all passengers died due to lack of oxygen. The autopilot was in control and the aircraft crashed after the fuel was empty.
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Starlionblue
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 8:00 am

Quoting Troubleshooter (Reply 2):
I heard a story about a Learjet with a rapid decompression at a very high altitude. Both pilots and all passengers died due to lack of oxygen. The autopilot was in control and the aircraft crashed after the fuel was empty.

The aircraft was owned by a golfer. Can't remember which one.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
DAL7e7
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 8:11 am

Quoting Starlionblue (Reply 3):

The aircraft was owned by a golfer. Can't remember which one.

Were you thinking about Arnold Palmer? I'm not sure myself, just thought it sounded right.

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ltbewr
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 8:19 am

The aircraft where professional golfer was killed involved Payne Stewart, a high ranking PGA class player. He and others were flying from Orlando, FL to Texas. Somewhere over Georgia, there was a decompression event or pressurization failure and the pilot/co-pilot apparently not able to put O2 masks in time. The autopilot kept the original flight path, it was supposed to bank left over Georgia toward Houston, TX, but didn't and kept flying for about 4 hours until running out of fuel. This a/c did get well over 40,000 ft. during it's ghost flight. Here is a link for more info:
http://www.airsafe.com/stewart.htm

Apparently this has happened before, including an incident in or about 2000 in Australia.
 
citationjet
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 8:20 am

It was not Arnold Palmer, it was Payne Stewart in a Lear 35. Arnold Palmer owns and operates Citation X, N1AP.
http://www.ntsb.gov/NTSB/brief.asp?ev_id=20001212X19931&key=1
http://www.ntsb.gov/NTSB/brief2.asp?...212X19931&ntsbno=DCA00MA005&akey=1
http://www.ntsb.gov/NTSB/GenPDF.asp?id=DCA00MA005&rpt=fa

The idea of certifying to 51,000 ft was started by LearJet, merely as a marketing advantage only. Other manufacturers didn't want to be outdone so they did it also. This altitude is rarely used by airplanes certified to that altitude, and when they do they don't perform very well there.

Most LearJets, the Citation 650, Citation 750, Gulfstream G-V, and G-VSP are certified to 51,000 ft.

[Edited 2005-04-01 00:26:24]
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learpilot
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 8:42 am

Quoting Lemmy (Reply 1):
Question about emergency descent procedures: Are they generally flown manually...?

They are flown manually to ensure they are initiated immediately. The last thing you want to be doing during an explosive decompression is hoping you dialed the right altitude in the alerter, and pushed the correct button. Also, there are steps that the autopilot will not do, like retard the thrust levers (not all airplanes have autothrottles), extend the spoilers, and lower the landing gear. The learjet I fly will not even level at the altitude selected in the alerter. It must be leveled at the altitude manually and "Alt Hold" mode selected on the autopilot.

Now I do believe the Gulfstream 550 will automatically perform the emergency descent when the cabin altitude reaches a specific value. Aside from lowering the gear, I think it will do everything else to take you down to 15,000', level itself off, and maintain a programmed speed (I'm thinking @250 knots - been a couple of weeks since I read the article about it).

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411A
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 10:19 am

Sometimes the 'max operating altitude' for transport aircraft is artificially limited, due to pax oxygen requirements.

Case in point.
US Air BAC 1-11's (when they had 'em), max altitude FL250, due to NO pax oxygen fitted.
Likewise for all Lockheed Electras...no pax oxygen either.

However, in the case of above noted aircraft, ferry flights (with FD crew only) could be operated higher, if desired.
 
pilotpip
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 1:46 pm

I think that above FL510 all occupants must wear a pressurized breathing apparatus. The concorde had to get a special exemtion to this rule if I recall correctly.
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OPNLguy
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 2:13 pm

Quoting Troubleshooter (Reply 2):
Please someone correct me, if I�m wrong, but isn�t there a procedure that one cockpit member must wear the oxygen mask above a certain FL. This will reduce the risk for both pilots of getting unconscious if there is a rapid decompression. The time of usefull consciousness at this altitude is reduced to a few seconds!

Here in the USA, the reg is:

§ 91.211 Supplemental oxygen.

(a) General. No person may operate a civil aircraft of U.S. registry—

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and

(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.

(b) Pressurized cabin aircraft. (1) No person may operate a civil aircraft of U.S. registry with a pressurized cabin—

(i) At flight altitudes above flight level 250 unless at least a 10-minute supply of supplemental oxygen, in addition to any oxygen required to satisfy paragraph (a) of this section, is available for each occupant of the aircraft for use in the event that a descent is necessitated by loss of cabin pressurization; and

(ii) At flight altitudes above flight level 350 unless one pilot at the controls of the airplane is wearing and using an oxygen mask that is secured and sealed and that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL), except that the one pilot need not wear and use an oxygen mask while at or below flight level 410 if there are two pilots at the controls and each pilot has a quick-donning type of oxygen mask that can be placed on the face with one hand from the ready position within 5 seconds, supplying oxygen and properly secured and sealed.

(2) Notwithstanding paragraph (b)(1)(ii) of this section, if for any reason at any time it is necessary for one pilot to leave the controls of the aircraft when operating at flight altitudes above flight level 350, the remaining pilot at the controls shall put on and use an oxygen mask until the other pilot has returned to that crewmember's station.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
troubleshooter
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RE: Question About Max Operating Ceiling?

Fri Apr 01, 2005 7:20 pm

Quoting OPNLguy (Reply 10):
At flight altitudes above flight level 350 unless one pilot at the controls of the airplane is wearing and using an oxygen mask that is secured and sealed and that either supplies oxygen at all times or automatically supplies oxygen whenever the cabin pressure altitude of the airplane exceeds 14,000 feet (MSL),

That was the regulation I was talking about. Thanks for posting. I think a similar regulation exists for operation under EASA (JAA) rules.
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