Date: 201505
Local time of day: 0601-1200
Light: Dawn
Aircraft: EC135
Flight phase: Parked
Aircraft component: Cockpit Furnishing
Component problem: Design
Reporter organization: Air Taxi
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Physiological - Other; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Company Policy; Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Company Policy

Narrative: I am submitting this report to highlight a safety issue that is present with certain EC135 NVG Cockpit Lighting STCs. The safety issue is that when chin bubble floor mats are utilized while flying NVGs; the pilot's viewing field is restricted / limited while conducting landing operations in our flight profile. My primary concern for submitting this report is to express that the use of chin bubble floor mats; to comply with the STC; is an extremely unsafe practice. Glare shield curtains should be the Company's standard when given that option within the STC.Some NVG cockpit STCs require either the chin bubble floor mats or the cockpit glare shield curtains to be installed for NVG operations. I operate one of two EC135s as our primary aircraft and from time to time we operate another as a spare. I have found differences in what is or is not required by the STC's for each of these aircraft.One STC requires that either the chin bubble floor mats or the cockpit glare shield curtains be installed while using NVGs. While another STC does not require either in the limitations section; it only has a note stating that if external lights and/or cultural lighting causes distracting glare and reflections; the use of chin bubble carpets is recommended.All of these aircraft have similar landing light configurations yet only one makes it a requirement; a limitation; for either to be installed for NVG operations.I brought this topic up at a base safety meeting to see if the cockpit glareshield curtains could be installed in the one aircraft that requires either. Our mechanics said that the glareshield curtains could be installed and are currently waiting for upcoming scheduled maintenance to install them in the aircraft that has the requirement.Once again; utilization of the chin bubble floor mats restrict / limit the pilot's viewing field while conducting NVG operations which is an extremely unsafe practice. Glarshield curtains should be the Company's standard when given that option within the STC.

Callback: The reporter stated that two types of Night Vision Goggle (NVG) instrument light filters are authorized for the EC-135 by an STC. One is a curtain which snaps in on both sides of the cockpit then attach with Velcro along the glareshield front edge to hang down blocking extraneously light from the pilot's instrument. Pilots can see down through the chin bubble for obstructions during steep descents. The other type of instrument light filter is a black mat which lays over the chin bubble blocking out upward light which may interfere with a pilot's NVG instrument vision. The reporter does not believe the blackout matt is safe because all vision down through the chin bubble is blocked restricting the pilots' vision of obstacles and making landing descents less safe.



Synopsis: An EC-135 pilot reported when using Night Vision Goggles (NVG) and flying an aircraft which requires the instrument panel night vision external light shielding; the chin bubble mat blocks all downward vision thus obstructing obstacles during steep landing descents. The glareshield curtain permits downward vision but also filters the light from the instrument panels.