У вашего броузера проблема в совместимости с HTML5
Virtual Arantis Airways. Flight Simulator X-Plane 11.
Solution to modify taxi & landing lights brightness in X-Plane 11.
The modification works per aircraft.
P.S.
Remember always to take backup before modifying any file.
UPDATE:
Thanks to @cibrut you can make the same modification within PlaneMaker instead of modifying directly the object file.
There is also the explanation of what every value is about.
Please read the: http://forums.x-plane.org/index.php?/forums/topic/115255-taxi-landing-lights-are-very-dim/