Based on these incidents, in September 2007 the NTSB issued two Safety Recommendations to the Federal Aviation Administration (FAA) asking the agency to require the installation of redesigned window heating systems in all Boeing 747, 757, 767, and 777 series aircraft. These Safety Recommendations have yet to be implemented by the FAA.
(My emphasis).
Is this usual?
No thanks for that photo of the unit.... I do so hate electrical fires of any kind.