B737-800
Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action
ATC Equipment / Nav Facility / Buildings; Environment - Non Weather Related; Procedure
ILS to Runway 30 Miami. Weather was 900 foot ceiling with 3 miles vis. Two 747s were holding short of Runway 12/30 on Taxiway T and on Runway 09 (both were pointed east waiting to cross Runway 30; preparing to depart on Runway 27). As we passed 800 ft on the glideslope for Runway 30 with the runway in sight (100 ft below the ceiling) and the autopilot off; the glideslope began to dive for the ground. The glideslope interference was occurring from the two jumbo aircraft holding short of Runway 30. We reported the interference to Tower immediately. The jet behind us shortly reported the same anomaly after we landed. Had an autopilot been engaged; the aircraft would have commenced a dangerous dive beneath that PAPI visual path or ILS glideslope toward the ground. Glideslope interference from two large aircraft holding abeam the landing runway. Do not allow jumbo aircraft to hold short of Runway 30 when instrument condition are less than VFR conditions.
B737 First Officer reported a glideslope anomaly on the ILS to Runway 30 at MIA apparently caused by B747 aircraft holding on the taxiway in the vicinity of the end of the runway.