Commercial Fixed Wing
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Event / Encounter Other / Unknown
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Airport; Human Factors; Procedure
During the ILS Approach to 32 at KIND; the aircraft was cleared for approach at 3000 FT MSL (above the FAF altitude of 2400 FT MSL). Once established on final; the aircraft was configured and coupled for the approach. While awaiting for the GS to become 'alive'; the GS suddenly appeared and within 2 seconds showed the aircraft 2 dots above glide path. The autopilot immediately initiated a 2000 ft/min descent in an attempt to recapture the glide path. The Pilot flying (PF) immediately disconnected the autopilot. The GS indicator continued to be erratic for another few seconds before stabilizing. The decision was made to step down to 2400 FT MSL (the FAF altitude on the approach plate). During the descent; the GS indicator continued to be stable and appeared to display correct glide path guidance. Upon reaching the FAF altitude; the GS indicator remained stable and showed correct guidance and agreed with known aircraft parameters (known descent rates). During the descent on the GS and upon breaking out into VMC; the GS again began to act erratically. The approach was continued visually with the PAPI guidance to an uneventful landing. The Tower was informed of the issue. During the approach; it was noticed several large/heavy cargo aircraft had departed on the runway prior to our arrival. Once on the ground; Tower made comments to the large aircraft taxiing to remain outside the ILS critical area. It was noticed during the taxi to the gate that Ground Control was stressing the outbound cargo aircraft to remain short of the ILS critical area (short of N3 taxiway). During the subsequent departure back to ZZZ1; we noticed the ILS antenna was located abeam the taxiway adjacent to the cargo ramp and witnessed a large/heavy cargo aircraft not holding short of the critical area during a departure. Recommend IND Approach/Ground Control coordinate and stress the ILS critical area to avoid large aircraft from potentially interfering with the GP antenna located abeam the N3 taxiway.
Air carrier pilot reported erratic glide slope indications; later realizing ATC was not protecting ILS critical areas.