Narrative:

During cruise; first officer discovered the green hydraulic system quantity indication decreasing. It appeared to be a slow leak; but also thought it might be due to cold soaking. While monitoring the situation; I sent an ACARS message to maintenance explaining the quantity indication was approaching the low level amber box; but no response. Sent another message asking if anyone was home and still no response. Contacted dispatcher and he established a VHF conference call. All parties agreed we would be prepared in case the green system failed. Instead of waiting for an ECAM to appear; we decided to be proactive and review the irregular procedure for green hydraulic low level; accomplish the performance computations and brief the flight attendants on the potential of a cabin advisory in advance. Upon initiating our descent received an ECAM for green hydraulic low level and accomplished the procedure. I then notified ATC of our issue and after a brief discussion with the first officer; elected to declare an emergency as a precautionary measure. We then sent an ACARS to dispatch and maintenance confirming our mechanical problem and briefed the flight attendants on a cabin advisory; followed by a PA to the passengers informing them of situation and what they could expect. Fortunately; when we turned the green hydraulic pump back on; per the ECAM; we regained enough hydraulic quantity to put the landing gear down; land without incident and taxi to the gate. Crash fire rescue equipment followed us to the gate and the flight was complete at this point. Note: I felt the entire crew; dispatcher; ATC and crash fire rescue equipment all performed extremely well; but with respect to maintenance I have some concern. Throughout the majority of my career; maintenance was considered to be a valuable resource and the technical experts we could rely on. I do not find this to be the case anymore; especially with the individual that was on duty during this event. Unfortunately; maintenance control has become extremely inconsistent; depending on which controller we draw for the day. This is a non-emotional comment and I strongly believe this issue needs to be addressed. Also prior to our landing; ATC departed a heavy aircraft; which left behind some wake turbulence we had to confront during flare. Had we been dealing with a controllability issue; this would not have been a good situation. I called the tower from my hotel that evening and briefed them on what had transpired.

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Original NASA ASRS Text

Title: An A320 Captain reported losing Green hydraulic system fluid in cruise flight. They ran the procedure; and after coordinating with Dispatch and Maintenance decided to declare an emergency. A normal landing was made although they encountered some wake turbulence on short final.

Narrative: During cruise; First Officer discovered the Green Hydraulic System quantity indication decreasing. It appeared to be a slow leak; but also thought it might be due to cold soaking. While monitoring the situation; I sent an ACARS message to Maintenance explaining the quantity indication was approaching the low level amber box; but no response. Sent another message asking if anyone was home and still no response. Contacted Dispatcher and he established a VHF conference call. All parties agreed we would be prepared in case the Green System failed. Instead of waiting for an ECAM to appear; we decided to be proactive and review the irregular procedure for Green Hydraulic Low Level; accomplish the performance computations and brief the Flight Attendants on the potential of a cabin advisory in advance. Upon initiating our descent received an ECAM for Green Hydraulic Low Level and accomplished the procedure. I then notified ATC of our issue and after a brief discussion with the First Officer; elected to declare an emergency as a precautionary measure. We then sent an ACARS to Dispatch and Maintenance confirming our mechanical problem and briefed the Flight Attendants on a cabin advisory; followed by a PA to the passengers informing them of situation and what they could expect. Fortunately; when we turned the Green Hydraulic Pump back on; per the ECAM; we regained enough hydraulic quantity to put the landing gear down; land without incident and taxi to the gate. CFR followed us to the gate and the flight was complete at this point. NOTE: I felt the entire crew; Dispatcher; ATC and CFR all performed extremely well; but with respect to Maintenance I have some concern. Throughout the majority of my career; Maintenance was considered to be a valuable resource and the technical experts we could rely on. I do not find this to be the case anymore; especially with the individual that was on duty during this event. Unfortunately; Maintenance Control has become extremely inconsistent; depending on which controller we draw for the day. This is a non-emotional comment and I strongly believe this issue needs to be addressed. Also prior to our landing; ATC departed a heavy aircraft; which left behind some wake turbulence we had to confront during flare. Had we been dealing with a controllability issue; this would not have been a good situation. I called the Tower from my hotel that evening and briefed them on what had transpired.

Data retrieved from NASA's ASRS site as of April 2012 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.