Helicopter
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 40; Flight Crew Total 3700; Flight Crew Type 450
Situational Awareness; Distraction; Human-Machine Interface
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Other / Unknown
General None Reported / Taken
ATC Equipment / Nav Facility / Buildings; Environment - Non Weather Related
Lost GPS reception to GARMIN 530 and 430 while landing at rooftop helipad of [an LA hospital]. Looked at satellite reception page and only one satellite was available with minimal reception. Shutdown and started 10 minutes later and GPS's reacquired with no problem. No loss of reception when departing.
The reporter stated the approach path to the hospital is over fixed ground track and that the signal disruption begins a short time before landing so that by touchdown the GPS display automatically transitions to the satellite acquire page where no satellites are shown. After landing the signal slowly return. He believes some type of interference is radiating from the facility; but when he inquired was told there was no equipment operating the GPS L Band.
An Air Ambulance pilot reported the simultaneous loss of his Garmin 530 and 430 GPS signals while landing on a hospital helipad but the signals were reacquired with 10 minutes with normal operations during departure.