Gulfstream loss of cabin pressure question

[JimNtexas]

Howdy,

I was talking about high altitude flight with a friend the other day, and this possible factoid popped into my mind.

I have a memory of having read somewhere that some Gulfstreams are so smart that if they lose cabin pressure and the pilots don't react, then the airplane on its own will turn 45 degrees, squawk 7700, and descend.

Is this really the case, or is my imagination running away with me?

 

[g4800xp]

I know my G4 won't but I think the G5 and the Global will, as well as some Lear Jets, all the about can get to FL510.

 

[blzr]

Saw a Global yesterday in PBI. What do you have to major in in college to buy one of those babys? Thing must be a couple of Mil at least.

 

[gear goes down]

why whould it turn 45 degrees???

 

[ExpWayVis31]

why whould it turn 45 degrees???

To get you off the airway

 

[banned username 2]

Howdy,

I was talking about high altitude flight with a friend the other day, and this possible factoid popped into my mind.

I have a memory of having read somewhere that some Gulfstreams are so smart that if they lose cabin pressure and the pilots don't react, then the airplane on its own will turn 45 degrees, squawk 7700, and descend.

Is this really the case, or is my imagination running away with me?

The G-V will (if autopilot and autothrottles are engaged) and you are above FL410 and the cabin loses pressure, the autothrottles will come to idle, the aircraft will turn 90° to the left and it will descend at Mmo/Vmo to 15,000 ft and level off. The G-550 will engage the autothrottles and autopilot if they are disengaged and do the same thing...

 

[nwa_contrails]

Straight from Google and Gulfstream:

"The G500 also provides an exceptional, advanced safety feature, the Automatic Emergency Descent Mode, builtinto the Flight Management System. In the unlikely event of a rapid cabin depressurization at 40,000 feet orabove, coupled with crew incapacitation, the G500 will automatically turn and descend to a safe altitude of 15,000feet and a speed of 250 knots. This allows the flight crew to regain consciousness and resume control of theaircraft with plenty of altitude to spare. The G500, along with the Gulfstream G550, are the only aircraft in the ultra-long-range class to offer this extraordinary level of safety for your passengers and crew."
http://www.gulfstream.com/_forms/_brochures/mini/3355_g500_mini_reprint.pdf

Pretty cool, never knew about that...

 

[nwa_contrails]

Damn you beat me to it!

 

[paulsalem]

What if your over mountinus terrain that exceeds 15,000 feet? Will the GPWS over ride it?

 

[sigler]

The G-V will (if autopilot and autothrottles are engaged) and you are above FL410 and the cabin loses pressure, the autothrottles will come to idle, the aircraft will turn 90° to the left and it will descend at Mmo/Vmo to 15,000 ft and level off. The G-550 will engage the autothrottles and autopilot if they are disengaged and do the same thing...

Just a couple of things: on the Automatic Descent Mode, the G-550 will not engage the autopilot, just the autothottle (not that anyone ever flies with the A/P disengaged above 400 anyway). And once level at 15000, the speed goes to 250 kts.

 

[A Squared]

So if you happen to be flying over Nepal, you're hosed anyway

 

[JimNtexas]

Thank you gentlemen, that's very interesting. Perhaps the first step in a "refuse to crash" airplane. I wonder how long until airplanes will just turn away if the pilot aims at a the side of a mountain?

 

[User546]

The Raytheon Premiere has the same capability. The technology isn't just for the "bigger" jets!

 

[Learsforsale]

Saw a Global yesterday in PBI. What do you have to major in in college to buy one of those babys? Thing must be a couple of Mil at least.

Just a couple of mil, well $40M for a 2001 with 1300 hours. PM me if you are interested

 

[ReportCanoa]

To get you off the airway

Not really.

 

[sleddriver71]

Yea, I'm pretty sure I'd want to stay on the airway. I suppose it banks to prevent negative G's. That's how I was always taught to do emergency descents.

 

[Blackjet]

Yea, I'm pretty sure I'd want to stay on the airway

Don't know why you'd want to do that. You'll reek havoc on ATC and TCAS (both TCAS I and especially TCAS II w/Rev. 7 equipped aircraft due to the RAs it's going to be YELLING at the unsuspecting crew of the other aircraft) equipped aircraft, and those without TCAS, you might just run into them, and we both know that would not be good. Airways are not unidirectional, so you run the risk of a head on collision or descending onto the top of another aircraft. Getting off the airway would be the the right thing to do.

I suppose it banks to prevent negative G's. That's how I was always taught to do emergency descents.

No, just like the G drivers have stated, it banks in order to initiate the 90 degree turn to exit the airway. This decent is not the same configuration as an emergency decent; I don't recall anyone saying the the boards came out.