Unfortunately I have to mention an incident in Poland,
(no English knowledge involved)
where a CPT on a night IFR flight on ATR72 experiencing some
abnormalities and errors in HSI told the Copilot to "Reset it !",
resulting in total failure of systems and loss of spatial orientation.
They recovered and broke out of clouds using stand-by instruments,
came to straight and level, readjusted instruments and completed flight,
but in the process reached 2.6G almost disintegrating the AC.
Preliminary report here, unfortunately in Polish,
but visualisations available.
http://www.mi.gov.pl/2-4823096e55b13-1786572-p_1.htm
(click on: "Wizualizacja ścieżki..." and "Wizualizacja manewru..." to download)
This time no ATC support was available to help in recovery...