MD-82
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Wake Vortex Encounter
General None Reported / Taken
Procedure; Environment - Non Weather Related
Approximately 40 miles west of FQM; level cruise at FL310; Mach .77 assigned by ATC. [We] noted a 25 KT tailwind at FL310 on the airway. The TCAS display was not showing known targets on the display and I would be writing it up on arrival. We had just descended from FL330 and shortly after leveling off at FL310 we began to feel the buffet from the wake of an aircraft in front of us. We did not see the traffic on the TCAS display since it was not showing known targets. We asked Cleveland Center if we were following someone and Cleveland replied that we were following lots of aircraft. We visually acquired an aircraft in front of us and guessed that we were about five miles in trail. My aircraft encountered the wake turbulence from the aircraft in front of us and made about a 25 degree roll to the right; followed by a 25 degree roll left. It was by no means a snap roll; just a pronounced gradual right wing down followed by the pronounced left wing down with no loss of altitude. I disconnected the autopilot and autothrottle during the recovery as we reported the event to ATC and asked for a descent to get out of the wake. Cleveland Center gave us a descent to FL250 and told us to maintain 250 KTS. We asked Cleveland how far we were behind the aircraft in front of us and Cleveland told us that we were seven miles in trail. We asked the type of aircraft and Cleveland told us we were following an Airbus A319.There were no unusual attitudes encountered and no deviations from clearances or procedures. I am just submitting this report because we did encounter wake turbulence from an aircraft in front of us where we did have the required separation and it surprised me that we were tossed around from a small aircraft. Suggestions: Inform the aviation community of the flight data results from A319 flight tests showing the severity of wake turbulence generated. Was my encounter today an anomaly or is there a bigger wake generated by the A319? Exactly where does the A319 fall in the spectrum of wake turbulence generated by modern aircraft? A chart that comparatively quantifies and illustrates the wake severity of the most common commercial aircraft flying today would be most useful. Does such a chart exist and if so; where can I obtain the chart?
MD-82 Captain reported wake vortex encounter at FL310 five miles in trail of an A319 resulting in a 25 degree roll in both directions. Reporter was surprised at the intensity of the encounter given the relatively small aircraft he was following.