Narrative:

On the SILOW1 departure off of phx runway 7L; our A320 encountered the wake(south) of a leading A320 on the same departure. We were cleared for takeoff from 'position and hold' just as the leading A320 rotated. The winds were reported 010 at 7 knots. After takeoff; we normally accelerate to 250 at 3000 ft AGL. After flap retraction/acceleration; we discussed additional wake avoidance and; as we were restr on the SID; we elected to continue to climb at 'green DOT' (best climb) due to wake concerns and to increase the distance between us and the lead A320 (it was just over the 2.5 NM ring on the navigation display based on TCAS ranging -- maybe 3 NM; probably less at about 2000 ft MSL). During this part of the climb; I noted the winds aloft were 040/4. The captain was hand flying slightly left (upwind) of the FMGC computed LNAV track (slight right roll bar command on my pfd). This was all before the encounter. At about 4500 ft; we got the 'nibbles' and I said; 'here it comes; the wind has shifted to the right.' then; after 10 seconds; we banked l-r-left (5-10 degree). The captain was countering the uncommanded rolls with side stick inputs which he later said were about 1/2 side stick to r-l-right -- opposite to the wake induced rolls. (Ab side sticks do not move together; so PNF does not get any feedback on the inputs of the PF; and no one gets any feedback if ap is on.) we were out of the wake in about 2-4 seconds and the captain now flew right of the SID (it says heading 075 degrees until 4 DME) at about 070 degrees (upwind). I noted the wind was now 180/15 at 6000 ft. At the encounter; we were at about 4 NM in trail based on TCAS ranging. Departure gave us a left turn to the north and then gave the lead A320 a left turn to the northeast. Our tracks diverged. I reported the encounter to ATC when he handed us off to center -- maybe 5 minutes after the event. I did tell him that it was at 3.7 DME and at 4800 ft. This is the my second departure ever from phx and; surprisingly; I am 2 for 2 having wake encounters there. Both times; the separation was legal at the time of the encounter. I hesitate to say it was safe. Certainly; the outcome was not severe for us (would an rj have had a similar encounter); but the 'events' should not have happened at this frequency.

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Original NASA ASRS Text

Title: A320 FLT CREW ENCOUNTERS WAKE TURB FROM PRECEDING A320 AT 4700 FT ON THE SILOW1 DEP PHX.

Narrative: ON THE SILOW1 DEP OFF OF PHX RWY 7L; OUR A320 ENCOUNTERED THE WAKE(S) OF A LEADING A320 ON THE SAME DEP. WE WERE CLRED FOR TKOF FROM 'POSITION AND HOLD' JUST AS THE LEADING A320 ROTATED. THE WINDS WERE RPTED 010 AT 7 KNOTS. AFTER TAKEOFF; WE NORMALLY ACCELERATE TO 250 AT 3000 FT AGL. AFTER FLAP RETRACTION/ACCELERATION; WE DISCUSSED ADDITIONAL WAKE AVOIDANCE AND; AS WE WERE RESTR ON THE SID; WE ELECTED TO CONTINUE TO CLB AT 'GREEN DOT' (BEST CLB) DUE TO WAKE CONCERNS AND TO INCREASE THE DISTANCE BETWEEN US AND THE LEAD A320 (IT WAS JUST OVER THE 2.5 NM RING ON THE NAV DISPLAY BASED ON TCAS RANGING -- MAYBE 3 NM; PROBABLY LESS AT ABOUT 2000 FT MSL). DURING THIS PART OF THE CLB; I NOTED THE WINDS ALOFT WERE 040/4. THE CAPT WAS HAND FLYING SLIGHTLY LEFT (UPWIND) OF THE FMGC COMPUTED LNAV TRACK (SLIGHT RIGHT ROLL BAR COMMAND ON MY PFD). THIS WAS ALL BEFORE THE ENCOUNTER. AT ABOUT 4500 FT; WE GOT THE 'NIBBLES' AND I SAID; 'HERE IT COMES; THE WIND HAS SHIFTED TO THE RIGHT.' THEN; AFTER 10 SECONDS; WE BANKED L-R-L (5-10 DEG). THE CAPT WAS COUNTERING THE UNCOMMANDED ROLLS WITH SIDE STICK INPUTS WHICH HE LATER SAID WERE ABOUT 1/2 SIDE STICK TO R-L-R -- OPPOSITE TO THE WAKE INDUCED ROLLS. (AB SIDE STICKS DO NOT MOVE TOGETHER; SO PNF DOES NOT GET ANY FEEDBACK ON THE INPUTS OF THE PF; AND NO ONE GETS ANY FEEDBACK IF AP IS ON.) WE WERE OUT OF THE WAKE IN ABOUT 2-4 SECONDS AND THE CAPT NOW FLEW RIGHT OF THE SID (IT SAYS HEADING 075 DEGS UNTIL 4 DME) AT ABOUT 070 DEGS (UPWIND). I NOTED THE WIND WAS NOW 180/15 AT 6000 FT. AT THE ENCOUNTER; WE WERE AT ABOUT 4 NM IN TRAIL BASED ON TCAS RANGING. DEP GAVE US A LEFT TURN TO THE NORTH AND THEN GAVE THE LEAD A320 A LEFT TURN TO THE NE. OUR TRACKS DIVERGED. I RPTED THE ENCOUNTER TO ATC WHEN HE HANDED US OFF TO CENTER -- MAYBE 5 MINUTES AFTER THE EVENT. I DID TELL HIM THAT IT WAS AT 3.7 DME AND AT 4800 FT. THIS IS THE MY SECOND DEP EVER FROM PHX AND; SURPRISINGLY; I AM 2 FOR 2 HAVING WAKE ENCOUNTERS THERE. BOTH TIMES; THE SEPARATION WAS LEGAL AT THE TIME OF THE ENCOUNTER. I HESITATE TO SAY IT WAS SAFE. CERTAINLY; THE OUTCOME WAS NOT SEVERE FOR US (WOULD AN RJ HAVE HAD A SIMILAR ENCOUNTER); BUT THE 'EVENTS' SHOULD NOT HAVE HAPPENED AT THIS FREQUENCY.

Data retrieved from NASA's ASRS site as of January 2009 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.