B737-200 crew had an 'a' system hydraulic failure in ZDC class a airspace.

Attributes
ACN	508001
Time
Date	200104
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : orf.airport
State Reference	VA
Altitude	msl single value : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 35 flight time total : 9600 flight time type : 3000
ASRS Report	508001
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial pilot : cfi pilot : atp
Experience	flight time last 90 days : 180 flight time total : 7000 flight time type : 2500
ASRS Report	508694
Events
Anomaly	aircraft equipment problem : critical other anomaly other other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : landed in emergency condition flight crew : diverted to another airport flight crew : declared emergency none taken : detected after the fact
Consequence	other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

At FL280, we noticed 'a' system quantity rapidly decreasing. Not knowing if we would lose 'a' and 'B' system hydraulics, we descended to FL200 -- considering the fact that may have control problems in manual reversion. Prior to FL200, 'a' system low pressure light illuminated. While discussing with dispatch, we declared an emergency and were diverting to clt. All QRH procedures were completed and landed in clt with no further incident.

Original NASA ASRS Text

Title: B737-200 CREW HAD AN 'A' SYS HYD FAILURE IN ZDC CLASS A AIRSPACE.

Narrative: AT FL280, WE NOTICED 'A' SYS QUANTITY RAPIDLY DECREASING. NOT KNOWING IF WE WOULD LOSE 'A' AND 'B' SYS HYDS, WE DSNDED TO FL200 -- CONSIDERING THE FACT THAT MAY HAVE CTL PROBS IN MANUAL REVERSION. PRIOR TO FL200, 'A' SYS LOW PRESSURE LIGHT ILLUMINATED. WHILE DISCUSSING WITH DISPATCH, WE DECLARED AN EMER AND WERE DIVERTING TO CLT. ALL QRH PROCS WERE COMPLETED AND LANDED IN CLT WITH NO FURTHER INCIDENT.

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.