While making an emergency descent due to a loss of pressurization at FL350 the flight crew of a g-iv...

Attributes
ACN	1075839
Time
Date	201303
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream IV / G350 / G450
Operating Under FAR Part	Part 91
Flight Phase	Climb
Route In Use	Direct
Flight Plan	IFR
Component
Aircraft Component	Pressurization System
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 115 Flight Crew Total 5800 Flight Crew Type 500
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Overshoot Deviation - Procedural Clearance

Narrative:

As we were climbing through FL350; the cabin altitude started to climb. I put on my oxygen mask; contacted ATC and told them I needed to descend immediately. I was cleared to FL240. As the cabin altitude rapidly climbed through 14;000 ft I initiated an emergency descent; declared an emergency and requested a lower altitude. I was re-cleared to 11;000 ft. As a result of my rapid rate of descent; I descended 300 ft below my assigned altitude as I leveled off but immediately climbed back up to 11;000 where we were given a heading while we assessed the situation. None of the passengers or crew was injured. We cancelled the emergency and continued to our destination at a lower altitude. Closer to our destination we diverted to another airfield for maintenance. In the future I would try to start arresting my descent rate earlier in order not to descend below my assigned altitude. Today I realized the importance of the use of oxygen masks at high altitude and the training that we receive regarding emergency descents. I am very thankful for both. Without oxygen this situation could have ended up much worse.

Original NASA ASRS Text

Title: While making an emergency descent due to a loss of pressurization at FL350 the flight crew of a G-IV descended 300 FT below their cleared altitude of 11;000 MSL before recovering.

Narrative: As we were climbing through FL350; the cabin altitude started to climb. I put on my oxygen mask; contacted ATC and told them I needed to descend immediately. I was cleared to FL240. As the cabin altitude rapidly climbed through 14;000 FT I initiated an emergency descent; declared an emergency and requested a lower altitude. I was re-cleared to 11;000 FT. As a result of my rapid rate of descent; I descended 300 FT below my assigned altitude as I leveled off but immediately climbed back up to 11;000 where we were given a heading while we assessed the situation. None of the passengers or crew was injured. We cancelled the emergency and continued to our destination at a lower altitude. Closer to our destination we diverted to another airfield for maintenance. In the future I would try to start arresting my descent rate earlier in order not to descend below my assigned altitude. Today I realized the importance of the use of oxygen masks at high altitude and the training that we receive regarding emergency descents. I am very thankful for both. Without oxygen this situation could have ended up much worse.

Data retrieved from NASA's ASRS site as of July 2013 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.

While making an emergency descent due to a loss of pressurization at FL350 the flight crew of a g-iv descended 300 ft below their cleared altitude of 11;000 MSL before recovering.