PLTDEV FROM ASSIGNED ALT. ALTDEV ALT EXCURSION.

Narrative

I WAS IN CRUISE FLT AT 9000 FT; ENRTE FROM BLH TO PHX. THE L FRONT WINDSHIELD WAS SHATTERED BY AN UNKNOWN OBJECT. I INFORMED ZAB OF THE SITUATION AND ASKED FOR A LOWER ALT AND VECTORS TO THE NEAREST ARPT. I WAS ISSUED 6000 FT; THEN LATER 5000 FT. I WAS TOLD THAT 5000 FT WAS THE LOWEST I COULD GO ON THE AIRWAY. AT 5000 FT I WAS STILL IMC. I WAS BEING VECTORED TO BUCKEYE MUNICIPAL ARPT (BXK). WHEN OVER THE ARPT I WAS STILL IMC AND UNABLE TO LOCATE IT. THERE IS NO IFR APCH TO BXK ARPT. SINCE I WAS UNABLE TO LOCATE BXK I OPTED TO CONTINUE TOWARDS PHX WITH THE HOPE OF LOCATING ANOTHER ARPT. I WAS HANDED OFF TO PHX APCH. PHX APCH ADVISED ME THAT THE WX AT PHX WAS DETERIORATING. AT THE SAME TIME; I SPOTTED AN ARPT AT MY 3 O'CLOCK. PHX TOLD ME IT WAS BXK. I TOLD THEM I INTENDED TO LAND THERE AND BEGAN MY DSCNT. I WAS NEVER CLRED OUT OF 5000 FT AND I HAD NEVER ACTUALLY DECLARED AN EMER. BEING SO EAGER TO GET ON THE GND I LEFT AN ASSIGNED ALT WITHOUT A CLRNC AND WITHOUT THE BENEFITS PROVIDED BY THE PIC'S AUTHORITY TO DEVIATE FROM THE RULES IN AN EMER SITUATION.