Gulfstream iv flight crew experienced a cabin pressure annunciator at FL410 and initiated an emergen...

Attributes
ACN	909729
Time
Date	201009
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZZ.ARTCC
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream IV / G350 / G450
Operating Under FAR Part	Part 135
Flight Phase	Cruise
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 52 Flight Crew Total 9203 Flight Crew Type 892
Person 2
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 50 Flight Crew Total 9000 Flight Crew Type 150
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy

Narrative:

At FL410; had cabin pressure enunciator illuminate on cas. As per checklist donned oxygen mask; and began emergency descent. We notified ATC of problem and of our descent due to pressurization problems. We manually deployed the passenger oxygen masks and notified the cabin server of our condition. Center then asked us if we meant to be squawking 7500 and that is when I looked down and noticed the co-pilot had mistakenly put it the wrong code. Through FL250 we regained pressurization control and leveled off at FL180. We told center that we have regained pressurization control and would like to continue to destination at FL180 and were approved. Center said that they were still showing that we were squawking 7500. We verified that we were squawking 7700 but requested to now squak our assigned code as the emergency was over. Center approved the assigned squak. We landed with no further problems.

Original NASA ASRS Text

Title: Gulfstream IV flight crew experienced a cabin pressure annunciator at FL410 and initiated an emergency descent. Descending out of FL250 cabin pressure control was regained and the flight continued to their destination at FL180.

Narrative: At FL410; had cabin pressure enunciator illuminate on CAS. As per checklist donned oxygen mask; and began emergency descent. We notified ATC of problem and of our descent due to pressurization problems. We manually deployed the passenger oxygen masks and notified the cabin server of our condition. Center then asked us if we meant to be squawking 7500 and that is when I looked down and noticed the co-pilot had mistakenly put it the wrong code. Through FL250 we regained pressurization control and leveled off at FL180. We told Center that we have regained pressurization control and would like to continue to destination at FL180 and were approved. Center said that they were still showing that we were squawking 7500. We verified that we were squawking 7700 but requested to now squak our assigned code as the emergency was over. Center approved the assigned squak. We landed with no further problems.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Gulfstream iv flight crew experienced a cabin pressure annunciator at FL410 and initiated an emergency descent. Descending out of FL250 cabin pressure control was regained and the flight continued to their destination at FL180.