Narrative:

Steady at cruise; flight attendant notified me that smoke was filling the cabin and it appeared to be billowing from over-wing area and that they were investigating. No indication of smoke/fumes in flight deck and no indication of a mechanical malfunction. Flight attendant called back very soon to inform me that smoke was becoming denser and that passengers were leaving their seats over-wing to escape to galleys and that we needed to land soon. She stated the smoke smelled electrical. We [advised ATC] and pointed to [a nearby] airport knowing that we also had [other] airports available along that path as well. I relinquished flying duties to the first officer and activated the passenger oxygen mask system and told fas to get the passenger back into their seats. Still no smoke or fumes on the flight deck. Soon thereafter we received an ECAM warning of yellow hydraulic system low pressure. Hydraulic ECAM page also showed that we were losing yellow system fluid. I told fas that we were descending and diverting. Flight attendant called again to tell me that fas were donning pbes and breaking out fire extinguishers to 'fight the fire.' she hung up immediately. More concerned; I called her back immediately to confirm a fire. Lengthy delay for a response; but she admitted it was a miscommunication; they were going to mid cabin to see if they could find a fire and extinguish it. There was no fire in the cabin. After executing ECAM actions; which included deactivating the yellow pump; and completing smoke/fumes checklist; the smoke started to dissipate rapidly and calm returned to the cabin. Never did have indication of smoke or fumes on the flight deck. Given the loss of systems associated with the yellow hydraulic system loss and the dissipation of the smoke; I elected to divert due to the availability of long runways and the distance needed just to descend. First officer retained pilot flying duties through landing while I executed all checklists and briefed him on all approach considerations associated with the hydraulic failure. Also informed ATC that we were exceeding 250 kts below 10000 feet MSL in order to land quickly. ATC was most accommodating throughout the event and gave us our choice of runways. After clearing runway; fire department confirmed that there was no fire; smoke; or leaks coming from aircraft. We taxied to the gate and deplaned.

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Original NASA ASRS Text

Title: A319 Captain reported diverting to a nearby; suitable alternate when smoke filled the cabin following a yellow hydraulic system anomaly.

Narrative: Steady at cruise; FA notified me that smoke was filling the cabin and it appeared to be billowing from over-wing area and that they were investigating. No indication of smoke/fumes in flight deck and no indication of a mechanical malfunction. FA called back very soon to inform me that smoke was becoming denser and that passengers were leaving their seats over-wing to escape to galleys and that we needed to land soon. She stated the smoke smelled electrical. We [advised ATC] and pointed to [a nearby] airport knowing that we also had [other] airports available along that path as well. I relinquished flying duties to the FO and activated the PAX oxygen mask system and told FAs to get the PAX back into their seats. Still no smoke or fumes on the flight deck. Soon thereafter we received an ECAM warning of Yellow Hydraulic System low pressure. Hydraulic ECAM page also showed that we were losing Yellow System fluid. I told FAs that we were descending and diverting. FA called again to tell me that FAs were donning PBEs and breaking out fire extinguishers to 'fight the fire.' She hung up immediately. More concerned; I called her back immediately to confirm a fire. Lengthy delay for a response; but she admitted it was a miscommunication; they were going to mid cabin to see if they could FIND a fire and extinguish it. There was no fire in the cabin. After executing ECAM actions; which included deactivating the Yellow pump; and completing Smoke/Fumes checklist; the smoke started to dissipate rapidly and calm returned to the cabin. Never did have indication of smoke or fumes on the flight deck. Given the loss of systems associated with the Yellow Hydraulic system loss and the dissipation of the smoke; I elected to divert due to the availability of long runways and the distance needed just to descend. FO retained pilot flying duties through landing while I executed all checklists and briefed him on all approach considerations associated with the hydraulic failure. Also informed ATC that we were exceeding 250 kts below 10000 feet MSL in order to land quickly. ATC was most accommodating throughout the event and gave us our choice of runways. After clearing runway; fire department confirmed that there was no fire; smoke; or leaks coming from aircraft. We taxied to the gate and deplaned.

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.