Narrative:

On our flight to bur, ZLA cleared us to bur via the fernando 4 arrival, ave transition. We were given progressive dscnts and were handed over to bur approach. We complied with the speed restriction shown on the chart and were handed off to bur approach. We were inside the fim VOR at 7000 ft MSL when bur approach said 'you are now cleared to the bur airport via the fernando 4 transition for the ILS 8 approach.' no mention was made of the altitude. The copilot put 4500 ft in the altitude alerter and said we could go down to 4500 ft. We had begun to descend when bur approach said descend and maintain 6000 ft. We were already at 5500 ft. There was not a conflict with traffic. When we told the controller that we were at 5500 ft he said just maintain 5000 ft. Perceptions by crew were that we were cleared for the ILS to bur. Controller's terminology of 'cleared to the bur airport via fernando 4 arrival ILS transition to runway 8 ILS' sounds an awful lot like cleared for the ILS approach. The controller should have restated maintain 7000 ft. Since we had already been cleared for the fernando 4 arrival, the bur controller gave it to us again and this time ILS transition to the runway 8 ILS without stating an altitude seemed to indicate that this was a new clearance.

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Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION BY CPR JET FLC WHEN THEY HAVE A CLRNC INTERP PROB.

Narrative: ON OUR FLT TO BUR, ZLA CLRED US TO BUR VIA THE FERNANDO 4 ARR, AVE TRANSITION. WE WERE GIVEN PROGRESSIVE DSCNTS AND WERE HANDED OVER TO BUR APCH. WE COMPLIED WITH THE SPD RESTRICTION SHOWN ON THE CHART AND WERE HANDED OFF TO BUR APCH. WE WERE INSIDE THE FIM VOR AT 7000 FT MSL WHEN BUR APCH SAID 'YOU ARE NOW CLRED TO THE BUR ARPT VIA THE FERNANDO 4 TRANSITION FOR THE ILS 8 APCH.' NO MENTION WAS MADE OF THE ALT. THE COPLT PUT 4500 FT IN THE ALT ALERTER AND SAID WE COULD GO DOWN TO 4500 FT. WE HAD BEGUN TO DSND WHEN BUR APCH SAID DSND AND MAINTAIN 6000 FT. WE WERE ALREADY AT 5500 FT. THERE WAS NOT A CONFLICT WITH TFC. WHEN WE TOLD THE CTLR THAT WE WERE AT 5500 FT HE SAID JUST MAINTAIN 5000 FT. PERCEPTIONS BY CREW WERE THAT WE WERE CLRED FOR THE ILS TO BUR. CTLR'S TERMINOLOGY OF 'CLRED TO THE BUR ARPT VIA FERNANDO 4 ARR ILS TRANSITION TO RWY 8 ILS' SOUNDS AN AWFUL LOT LIKE CLRED FOR THE ILS APCH. THE CTLR SHOULD HAVE RESTATED MAINTAIN 7000 FT. SINCE WE HAD ALREADY BEEN CLRED FOR THE FERNANDO 4 ARR, THE BUR CTLR GAVE IT TO US AGAIN AND THIS TIME ILS TRANSITION TO THE RWY 8 ILS WITHOUT STATING AN ALT SEEMED TO INDICATE THAT THIS WAS A NEW CLRNC.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.