A B737-200 on descent at FL180 declared an emergency and diverted due to complete loss of 'a' hydrau...

Attributes
ACN	419049
Time
Date	199811
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : las
State Reference	NV
Altitude	msl bound lower : 17000 msl bound upper : 18000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : las
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other other other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial pilot : atp pilot : instrument
ASRS Report	419049
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Flight xyz lax-las, night pairing, VMC, B737-200. During descent, 'a' system hydraulic low pressure (right) light began to flicker on overhead panel (along with master caution on recall). First officer was PF and remained PF. Captain ran QRH and during reading of QRH the second 'a' system low pressure light came on. Crew noticed 'a' system pressure to be modulating between 0 psi and 3000 psi. Then noticed 'a' system quantity approaching zero. We immediately lowered the landing gear handle and as 'a' system modulated up towards 3000 psi, the gear finally came down. Captain declared emergency requesting crash fire rescue equipment with las approach and ran the remainder of the QRH. Captain briefed flight attendants on 'test' emergency procedures, and flight attendants prepared cabin for emergency landing/possible evacuate/evacuation. Flight attendants were able to completely prepare cabin and a visual approach was made to runway 25R. After first officer touched down, captain took controls and was able to taxi off runway via braking for steering, where aircraft was brought to a stop/shutdown. Crash fire rescue equipment/operations agents confirmed aircraft was safe to tow to gate.

Original NASA ASRS Text

Title: A B737-200 ON DSCNT AT FL180 DECLARED AN EMER AND DIVERTED DUE TO COMPLETE LOSS OF 'A' HYD SYS PRESSURE AND QUANTITY. CAUSE UNKNOWN.

Narrative: FLT XYZ LAX-LAS, NIGHT PAIRING, VMC, B737-200. DURING DSCNT, 'A' SYS HYD LOW PRESSURE (R) LIGHT BEGAN TO FLICKER ON OVERHEAD PANEL (ALONG WITH MASTER CAUTION ON RECALL). FO WAS PF AND REMAINED PF. CAPT RAN QRH AND DURING READING OF QRH THE SECOND 'A' SYS LOW PRESSURE LIGHT CAME ON. CREW NOTICED 'A' SYS PRESSURE TO BE MODULATING BTWN 0 PSI AND 3000 PSI. THEN NOTICED 'A' SYS QUANTITY APCHING ZERO. WE IMMEDIATELY LOWERED THE LNDG GEAR HANDLE AND AS 'A' SYS MODULATED UP TOWARDS 3000 PSI, THE GEAR FINALLY CAME DOWN. CAPT DECLARED EMER REQUESTING CFR WITH LAS APCH AND RAN THE REMAINDER OF THE QRH. CAPT BRIEFED FLT ATTENDANTS ON 'TEST' EMER PROCS, AND FLT ATTENDANTS PREPARED CABIN FOR EMER LNDG/POSSIBLE EVAC. FLT ATTENDANTS WERE ABLE TO COMPLETELY PREPARE CABIN AND A VISUAL APCH WAS MADE TO RWY 25R. AFTER FO TOUCHED DOWN, CAPT TOOK CTLS AND WAS ABLE TO TAXI OFF RWY VIA BRAKING FOR STEERING, WHERE ACFT WAS BROUGHT TO A STOP/SHUTDOWN. CFR/OPS AGENTS CONFIRMED ACFT WAS SAFE TO TOW TO GATE.

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.

A B737-200 on descent at FL180 declared an emergency and diverted due to complete loss of 'a' hydraulic system pressure and quantity. Cause unknown.