Narrative:

The following is copied from the irregular report: 'on J584 approximately 50 mi west of slt VOR at FL290 we experienced loss of press. We requested lower altitude. ATC was confused by our request initially and denied us descent clearance. At this point cabin altitude reached 12000'...we therefore declared an emergency and began descent in VFR conditions, during which passenger were only slightly aware. We placed the previously placarded l-pac on, therefore preventing O2 masks from dropping out. Flight continued on to ewr at 13000.' the aircraft are now old; the aircraft system could not perform even at the lower altitude. The controller was probably surprised. His decisions are dictated by a computer. He could not respond in time. Therefore, we had to declare an emergency--my first in 22 yrs. As we got closer to home the urgency of the situation diminished for the controllers, so we got vectored around as usual. However, we were still busy trying to control the pressurization and went through the arrival route on an 080 degree heading. First officer pointed this out. I responded that we were on vectors, but insisted he clarify with ATC. Ny now wanted to know why we missed the arrival route. The next day I again flew the same aircraft. When the aircraft began to act up, I started down early and prevented a recurrence.

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Original NASA ASRS Text

Title: ACR MLG UNABLE TO MAINTAIN CABIN ALT DECLARED AN EMERGENCY TO GET LOWER ALT. DURING RADAR VECTORS TO STAR HEADING TRACK DEVIATION OCCURRED.

Narrative: THE FOLLOWING IS COPIED FROM THE IRREGULAR RPT: 'ON J584 APPROX 50 MI W OF SLT VOR AT FL290 WE EXPERIENCED LOSS OF PRESS. WE REQUESTED LOWER ALT. ATC WAS CONFUSED BY OUR REQUEST INITIALLY AND DENIED US DSNT CLRNC. AT THIS POINT CABIN ALT REACHED 12000'...WE THEREFORE DECLARED AN EMER AND BEGAN DSNT IN VFR CONDITIONS, DURING WHICH PAX WERE ONLY SLIGHTLY AWARE. WE PLACED THE PREVIOUSLY PLACARDED L-PAC ON, THEREFORE PREVENTING O2 MASKS FROM DROPPING OUT. FLT CONTINUED ON TO EWR AT 13000.' THE ACFT ARE NOW OLD; THE ACFT SYS COULD NOT PERFORM EVEN AT THE LOWER ALT. THE CTLR WAS PROBABLY SURPRISED. HIS DECISIONS ARE DICTATED BY A COMPUTER. HE COULD NOT RESPOND IN TIME. THEREFORE, WE HAD TO DECLARE AN EMER--MY FIRST IN 22 YRS. AS WE GOT CLOSER TO HOME THE URGENCY OF THE SITUATION DIMINISHED FOR THE CTLRS, SO WE GOT VECTORED AROUND AS USUAL. HOWEVER, WE WERE STILL BUSY TRYING TO CTL THE PRESSURIZATION AND WENT THROUGH THE ARR RTE ON AN 080 DEG HDG. F/O POINTED THIS OUT. I RESPONDED THAT WE WERE ON VECTORS, BUT INSISTED HE CLARIFY WITH ATC. NY NOW WANTED TO KNOW WHY WE MISSED THE ARR RTE. THE NEXT DAY I AGAIN FLEW THE SAME ACFT. WHEN THE ACFT BEGAN TO ACT UP, I STARTED DOWN EARLY AND PREVENTED A RECURRENCE.

Data retrieved from NASA's ASRS site as of July 2007 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.