Widebody Transport
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter CFTT / CFIT
General None Reported / Taken
Airport
On final approach to SEA 34R; Tower gave us a 'Low Altitude Alert' Call. Indications within the cockpit showed we were on glide slope. I informed the Tower. Approach continued to uneventful landing. I suspect the 2 aircraft that departed as we were on short final causing glide slope fluctuation; coupled with the 2.75 glide slope for Runway 34R ILS caused us to momentarily go below the threshold. Multiple departures on short final coupled with a 2.75 glide slope.
Captain reported receiving a Low Altitude Alert call from tower while on final approach and surmised that it was caused by multiple departures while on short final to SEA airport.