A319
Flight Crew Last 90 Days 150; Flight Crew Total 8800; Flight Crew Type 4200
Distraction; Training / Qualification; Troubleshooting
Aircraft Equipment Problem Less Severe
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Aircraft
I was acting as the pilot not flying. While climbing past FL260 at .79 Mach with the autopilot ON; the aircraft began vibrating unusually. It was in the light to moderate range and about two cycles per second. It seemed to intensify with time. The pilot turned OFF the autopilot and pulled the power back. The vibration became negligible as speed decreased. The total event time was about 20 seconds. We got clearance to level off at FL270. I ran through the systems pages and did not see anything unusual. The Captain suspected a flight control problem so he declared an emergency and requested priority handling and emergency responders at a nearby divert airport. The Captain briefed the Flight Attendants to expect normal operations but to prepare themselves mentally for a possible evacuation. The landing was uneventful.
An A319 began vibrating at about two cycles per second climbing through FL260 at M0.79 so the airspeed was slowed which decreased the vibration while the crew declared an emergency and diverted to a nearby airport.