Narrative:

During cruise we got a master caution light with the hydraulic cue illuminated in the 6 pack. I selected the hydraulic page and observed that system a was close to depleted and pressure was low. We performed the QRH procedure for loss of system a. I notified ATC of our loss of an aircraft system and declared an emergency. We attempted to contact dispatch through the cockpit airphone system but got disconnected after a few seconds. I made a few more attempts and could not re establish contact. I then used the ACARS page to notify dispatch of the loss of system a through the emergency prompt and put a message in the free text area. I called back and got all 3 flight attendants on the interphone at the same time. I explained to them what our issue was and what I thought would play out. A few minutes later I made a PA informing the passengers of same information as well. The first officer and I discussed our options to continue since 3 of the 4 runways were open and we had adequate landing distance; suitable weather conditions and other airfields nearby. After consulting the advisory landing distance charts we chose a flaps 30 landing with autobrakes 2 set. We asked for and received a long final. We were turned in about 15 miles from the runway. About 3 or 4 miles from the localizer intercept course we extended the gear manually. We had a normal touchdown and stopped on the runway centerline just short of high a speed taxiway. As we rolled out I advised the first officer to talk to ATC and that I would talk to the passengers. I advised them to remain seated and told them I would give them more information shortly. We had several emergency vehicles waiting as we rolled out. They radioed through the ground control frequency that they wanted to chock the airplane. I told them to hold off until we finished our shutdown checklist. We performed those items that were applicable to our condition at the time. APU running; flaps up; brakes parked; and after the 3 minute cool down we shut down the engines. Crash fire rescue equipment asked me to pass them the gear pins through the cockpit window. After a few minutes they radioed that they would wait for maintenance to do it since they were not trained. We were informed that there was a leak on the left main landing gear. They took several minutes and put some padding around it that they secured with duct tape. Approximately 40 minutes after landing we were towed to the gate. Maintenance was waiting when we arrived. I was told that the leak was coming from a rigid line on the left gear down lock actuator.

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Original NASA ASRS Text

Title: B737-800 Captain experiences a loss of hydraulic fluid in Hydraulic System A during cruise. The QRH procedures are complied with and the flight continues to destination for a normal landing with a tow to the gate.

Narrative: During cruise we got a Master Caution light with the HYD cue illuminated in the 6 pack. I selected the Hydraulic page and observed that System A was close to depleted and pressure was low. We performed the QRH procedure for Loss of System A. I notified ATC of our loss of an aircraft system and declared an emergency. We attempted to contact Dispatch through the Cockpit Airphone System but got disconnected after a few seconds. I made a few more attempts and could not re establish contact. I then used the ACARS page to notify Dispatch of the Loss of System A through the emergency prompt and put a message in the free text area. I called back and got all 3 flight attendants on the interphone at the same time. I explained to them what our issue was and what I thought would play out. A few minutes later I made a PA informing the passengers of same information as well. The First Officer and I discussed our options to continue since 3 of the 4 runways were open and we had adequate landing distance; suitable weather conditions and other airfields nearby. After consulting the Advisory Landing Distance charts we chose a flaps 30 landing with autobrakes 2 set. We asked for and received a long final. We were turned in about 15 miles from the runway. About 3 or 4 miles from the localizer intercept course we extended the gear manually. We had a normal touchdown and stopped on the runway centerline just short of high a speed taxiway. As we rolled out I advised the First Officer to talk to ATC and that I would talk to the passengers. I advised them to remain seated and told them I would give them more information shortly. We had several emergency vehicles waiting as we rolled out. They radioed through the Ground Control frequency that they wanted to chock the airplane. I told them to hold off until we finished our Shutdown Checklist. We performed those items that were applicable to our condition at the time. APU running; flaps up; brakes parked; and after the 3 minute cool down we shut down the engines. CFR asked me to pass them the gear pins through the cockpit window. After a few minutes they radioed that they would wait for Maintenance to do it since they were not trained. We were informed that there was a leak on the left main landing gear. They took several minutes and put some padding around it that they secured with duct tape. Approximately 40 minutes after landing we were towed to the gate. Maintenance was waiting when we arrived. I was told that the leak was coming from a rigid line on the left gear down lock actuator.

Data retrieved from NASA's ASRS site 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.