Narrative:

On approach into runway 9L at west palm beach ILS in the WX we were cleared down to 2000 ft. On a 180 degree heading, at 2000 ft on heading we were cleared to 'approximately 120 degree heading intercept localizer.' the controller then cleared us to what sounded like 'one two thousand, cleared for the approach.' I read that back and we put in 1200 ft for the altitude. We descended and intercepted the localizer (about 4 mi from FAF/rubin). At the FAF we realized we were low and that we misunderstood the controller, but by that time we had the field in sight and had an uneventful approach and landing. This mistake started out at our departure airport when we showed up at our aircraft. After preflting the airplane we were shuffled out of it to another aircraft (equipment change) and had to quickly do another preflight. This new airplane had 2 flaps locked out and no APU, so not only were we late, but we had a maintenance carryover to deal with and had to start at the gate. Although this put us out late, we did our jobs professionally and safely. Once we took off and were en route, we had a normal flight up till we were turned over to approach control. Approach control wanted us to tell them when we were slowing down so they could fit us in between aircraft for the ILS runway 9L approach into pbi. We had planned on configuring early due to the spoilers not working 100% and not allowing us to slow as quickly as normal. Between the heavy traffic on the radio, and several times 2 radios broadcasting with loud high squeal at the same time, there was a miscom from the controller. Readback by me of 'one two thousand' and, with the configuring of the aircraft at the same time, neither of us caught that I had put in 1200 into the altitude window. Neither the first officer nor I can think of what the 'one two thousand' was supposed to be. Heavy radio traffic and traffic at the arrival airport on approach control, and miscom between the controller and pilots were the major problems. The secondary problem was the mechanical problem we had to deal with that wasn't our normal working environment. Thirdly, the late swapping of equipment, nighttime and WX were additional factors that led up to our problems. Better communication, less traffic on approach in WX and less radio traffic would have probably alleviated our problems.

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Original NASA ASRS Text

Title: FLT CREW OF B757 MISINTERP ALT CLRNC FROM PBI APCH CTLR AND DSND BELOW PROCEDURAL ALT AT FAF ON ILS IAP TO RWY 9L AT PBI.

Narrative: ON APCH INTO RWY 9L AT WEST PALM BEACH ILS IN THE WX WE WERE CLRED DOWN TO 2000 FT. ON A 180 DEG HDG, AT 2000 FT ON HDG WE WERE CLRED TO 'APPROX 120 DEG HDG INTERCEPT LOC.' THE CTLR THEN CLRED US TO WHAT SOUNDED LIKE 'ONE TWO THOUSAND, CLRED FOR THE APCH.' I READ THAT BACK AND WE PUT IN 1200 FT FOR THE ALT. WE DSNDED AND INTERCEPTED THE LOC (ABOUT 4 MI FROM FAF/RUBIN). AT THE FAF WE REALIZED WE WERE LOW AND THAT WE MISUNDERSTOOD THE CTLR, BUT BY THAT TIME WE HAD THE FIELD IN SIGHT AND HAD AN UNEVENTFUL APCH AND LNDG. THIS MISTAKE STARTED OUT AT OUR DEP ARPT WHEN WE SHOWED UP AT OUR ACFT. AFTER PREFLTING THE AIRPLANE WE WERE SHUFFLED OUT OF IT TO ANOTHER ACFT (EQUIP CHANGE) AND HAD TO QUICKLY DO ANOTHER PREFLT. THIS NEW AIRPLANE HAD 2 FLAPS LOCKED OUT AND NO APU, SO NOT ONLY WERE WE LATE, BUT WE HAD A MAINT CARRYOVER TO DEAL WITH AND HAD TO START AT THE GATE. ALTHOUGH THIS PUT US OUT LATE, WE DID OUR JOBS PROFESSIONALLY AND SAFELY. ONCE WE TOOK OFF AND WERE ENRTE, WE HAD A NORMAL FLT UP TILL WE WERE TURNED OVER TO APCH CTL. APCH CTL WANTED US TO TELL THEM WHEN WE WERE SLOWING DOWN SO THEY COULD FIT US IN BTWN ACFT FOR THE ILS RWY 9L APCH INTO PBI. WE HAD PLANNED ON CONFIGURING EARLY DUE TO THE SPOILERS NOT WORKING 100% AND NOT ALLOWING US TO SLOW AS QUICKLY AS NORMAL. BTWN THE HVY TFC ON THE RADIO, AND SEVERAL TIMES 2 RADIOS BROADCASTING WITH LOUD HIGH SQUEAL AT THE SAME TIME, THERE WAS A MISCOM FROM THE CTLR. READBACK BY ME OF 'ONE TWO THOUSAND' AND, WITH THE CONFIGURING OF THE ACFT AT THE SAME TIME, NEITHER OF US CAUGHT THAT I HAD PUT IN 1200 INTO THE ALT WINDOW. NEITHER THE FO NOR I CAN THINK OF WHAT THE 'ONE TWO THOUSAND' WAS SUPPOSED TO BE. HVY RADIO TFC AND TFC AT THE ARR ARPT ON APCH CTL, AND MISCOM BTWN THE CTLR AND PLTS WERE THE MAJOR PROBS. THE SECONDARY PROB WAS THE MECHANICAL PROB WE HAD TO DEAL WITH THAT WASN'T OUR NORMAL WORKING ENVIRONMENT. THIRDLY, THE LATE SWAPPING OF EQUIP, NIGHTTIME AND WX WERE ADDITIONAL FACTORS THAT LED UP TO OUR PROBS. BETTER COM, LESS TFC ON APCH IN WX AND LESS RADIO TFC WOULD HAVE PROBABLY ALLEVIATED OUR PROBS.

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.