Narrative:

All aspects of the flight appeared normal until 4 mi final when, not having heard any radio transmission for several mi, I asked approach control if I should contact tower. I thought it odd that the controller said 'I guess the other guy is through talking to you, contact tower.' taxiing in, I was given a phone number to call at houston approach. My first officer and I reviewed the flight and could not think of any abnormalities, so I was a bit curious. I believe I talked to the person who was actually controling us and was surprised when his first comment was to ask if we were ok. I was stunned when he told me we had never been cleared to leave 3000 ft on the approach. Apparently he had been trying to talk to us for several mi, but we had heard nothing. The first officer was flying, descending to our cleared altitude of 3000 ft about 17 mi out, when another company flight checked in at 6000 ft with the field in sight. Thinking we had called, the controller cleared us for a visual approach. When I told him it was not us and that we did not have the field in sight, he told us to just intercept the localizer. Just after passing over ellington while turning to intercept we were given a TA about an aircraft turning final in front of us. At 3000 ft, on the localizer, we began to configure as the GS came alive. I noted that the approach mode had not yet been selected, looked away for the traffic then came back inside and saw that the approach mode was activated. The approach was completed to a normal landing. During the flight from msy, both the first officer and I noticed a clicking sound in the #1 radio when transmitting -- almost like the transmitter was cutting out. No receiving agency had said anything about a problem, but I had asked maintenance to replace the control head as a precaution. I do not think our receiver had failed, but we definitely heard nothing between the TA and the response to my request to contact tower. The first officer activated his approach clearance cue when we were originally cleared for the visual approach, but did not change it back when that clearance was changed. My cue (approach mode selected) was activated when I crosschecked it as we approached the glide path. Neither of us realized we had not been cleared out of 3000 ft for the approach. I had a very good, congenial conversation with the approach controller, who concluded 'no harm, no foul.' definitely a lapse in concentration on a 'normal, ordinary' approach. Supplemental information from acn 539104: we were vectored in high and close to the field to intercept final under VMC. While descending, past 5000 ft for 3000 ft, approach control issued a clearance to another aircraft using our call sign 'company flight number.' the captain corrected approach control. Our VHF #1 radio was 'ticking' on this first leg and we had called maintenance to come check it upon landing. After intercepting final, the aircraft was configured normally. What we did not know was that approach intended to leave us at 3000 ft until we passed west of ellington field (6 DME on final). VHF #1 was quiet as we approached GS intercept at 3000 ft, approximately 9 DME. I incorrectly selected approach mode on the autoplt MCP and began to descend on the GS. ATC called twice to ask us to halt our descent. Since our VHF #1 was bad, we did not hear these calls. I incorrectly interpreted ATC's initial clearance -- the one using our call sign, but intended for the other aircraft -- as a clearance to descend for a visual approach.

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Original NASA ASRS Text

Title: A B737-300 CREW, DSNDING INTO HOU, MISINTERPED A CLRNC AND STARTED FINAL DSCNT PREMATURELY. NUMEROUS CALLS FROM ATC WENT UNDETECTED DUE TO A #1 VHF PROB.

Narrative: ALL ASPECTS OF THE FLT APPEARED NORMAL UNTIL 4 MI FINAL WHEN, NOT HAVING HEARD ANY RADIO XMISSION FOR SEVERAL MI, I ASKED APCH CTL IF I SHOULD CONTACT TWR. I THOUGHT IT ODD THAT THE CTLR SAID 'I GUESS THE OTHER GUY IS THROUGH TALKING TO YOU, CONTACT TWR.' TAXIING IN, I WAS GIVEN A PHONE NUMBER TO CALL AT HOUSTON APCH. MY FO AND I REVIEWED THE FLT AND COULD NOT THINK OF ANY ABNORMALITIES, SO I WAS A BIT CURIOUS. I BELIEVE I TALKED TO THE PERSON WHO WAS ACTUALLY CTLING US AND WAS SURPRISED WHEN HIS FIRST COMMENT WAS TO ASK IF WE WERE OK. I WAS STUNNED WHEN HE TOLD ME WE HAD NEVER BEEN CLRED TO LEAVE 3000 FT ON THE APCH. APPARENTLY HE HAD BEEN TRYING TO TALK TO US FOR SEVERAL MI, BUT WE HAD HEARD NOTHING. THE FO WAS FLYING, DSNDING TO OUR CLRED ALT OF 3000 FT ABOUT 17 MI OUT, WHEN ANOTHER COMPANY FLT CHKED IN AT 6000 FT WITH THE FIELD IN SIGHT. THINKING WE HAD CALLED, THE CTLR CLRED US FOR A VISUAL APCH. WHEN I TOLD HIM IT WAS NOT US AND THAT WE DID NOT HAVE THE FIELD IN SIGHT, HE TOLD US TO JUST INTERCEPT THE LOC. JUST AFTER PASSING OVER ELLINGTON WHILE TURNING TO INTERCEPT WE WERE GIVEN A TA ABOUT AN ACFT TURNING FINAL IN FRONT OF US. AT 3000 FT, ON THE LOC, WE BEGAN TO CONFIGURE AS THE GS CAME ALIVE. I NOTED THAT THE APCH MODE HAD NOT YET BEEN SELECTED, LOOKED AWAY FOR THE TFC THEN CAME BACK INSIDE AND SAW THAT THE APCH MODE WAS ACTIVATED. THE APCH WAS COMPLETED TO A NORMAL LNDG. DURING THE FLT FROM MSY, BOTH THE FO AND I NOTICED A CLICKING SOUND IN THE #1 RADIO WHEN XMITTING -- ALMOST LIKE THE XMITTER WAS CUTTING OUT. NO RECEIVING AGENCY HAD SAID ANYTHING ABOUT A PROB, BUT I HAD ASKED MAINT TO REPLACE THE CTL HEAD AS A PRECAUTION. I DO NOT THINK OUR RECEIVER HAD FAILED, BUT WE DEFINITELY HEARD NOTHING BTWN THE TA AND THE RESPONSE TO MY REQUEST TO CONTACT TWR. THE FO ACTIVATED HIS APCH CLRNC CUE WHEN WE WERE ORIGINALLY CLRED FOR THE VISUAL APCH, BUT DID NOT CHANGE IT BACK WHEN THAT CLRNC WAS CHANGED. MY CUE (APCH MODE SELECTED) WAS ACTIVATED WHEN I XCHKED IT AS WE APCHED THE GLIDE PATH. NEITHER OF US REALIZED WE HAD NOT BEEN CLRED OUT OF 3000 FT FOR THE APCH. I HAD A VERY GOOD, CONGENIAL CONVERSATION WITH THE APCH CTLR, WHO CONCLUDED 'NO HARM, NO FOUL.' DEFINITELY A LAPSE IN CONCENTRATION ON A 'NORMAL, ORDINARY' APCH. SUPPLEMENTAL INFO FROM ACN 539104: WE WERE VECTORED IN HIGH AND CLOSE TO THE FIELD TO INTERCEPT FINAL UNDER VMC. WHILE DSNDING, PAST 5000 FT FOR 3000 FT, APCH CTL ISSUED A CLRNC TO ANOTHER ACFT USING OUR CALL SIGN 'COMPANY FLT NUMBER.' THE CAPT CORRECTED APCH CTL. OUR VHF #1 RADIO WAS 'TICKING' ON THIS FIRST LEG AND WE HAD CALLED MAINT TO COME CHK IT UPON LNDG. AFTER INTERCEPTING FINAL, THE ACFT WAS CONFIGURED NORMALLY. WHAT WE DID NOT KNOW WAS THAT APCH INTENDED TO LEAVE US AT 3000 FT UNTIL WE PASSED W OF ELLINGTON FIELD (6 DME ON FINAL). VHF #1 WAS QUIET AS WE APCHED GS INTERCEPT AT 3000 FT, APPROX 9 DME. I INCORRECTLY SELECTED APCH MODE ON THE AUTOPLT MCP AND BEGAN TO DSND ON THE GS. ATC CALLED TWICE TO ASK US TO HALT OUR DSCNT. SINCE OUR VHF #1 WAS BAD, WE DID NOT HEAR THESE CALLS. I INCORRECTLY INTERPED ATC'S INITIAL CLRNC -- THE ONE USING OUR CALL SIGN, BUT INTENDED FOR THE OTHER ACFT -- AS A CLRNC TO DSND FOR A VISUAL APCH.

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.