A319
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Ground Event / Encounter Ground Equipment Issue; Inflight Event / Encounter Unstabilized Approach
Flight Crew Overcame Equipment Problem
ATC Equipment / Nav Facility / Buildings; Airport; Aircraft
FO Flying / AP on in Nav mode. Just as we were making our turn to transition from the arrival to the approach. FO selected APP mode on FCU the LOC & GS  captured simultaneously . Initially the GS indicated below us but as soon as the aircraft went to capture mode the GS indication jumped above the 1/2 scale deflection up. The aircraft followed the GS as it moved up to 1/2 scale high until the aircraft pitch was approximately 20 degrees nose up. Thrust had been at idle so the speed vector showed a negative trend while the engines were trying to accelerate.  The power finally caught up and the nose came back down . We were able to continue the approach and land. I talked to the crew from the day before and they had a similar thing happen to them.  There is an airport very close to this intersection. I wonder if there maybe some interference from the [other] airport. If there is some interference we need to add a note to the 10-7 pages to warn the crews this situation could occur.
A319 Captain reported strong possibility of signal interference which resulted in erratic maneuvering of aircraft to autopilot.