Narrative:

On approach to ZZZ1, we were set up a little high from ATC. We were finally cleared for a visual behind another carrier's aircraft. I deployed the speed brakes to not only get down, but to also keep my spacing behind the aircraft. I was spending a lot of time xchking my energy state, my spacing, and maintaining a visual on a somewhat unfamiliar field. I lowered the landing gear at 230 KTS followed by flaps 5 degrees at 210 KTS. I was on GS with 5 mi to go. I was comfortable with my energy state and everything was coming together nicely. I called for flaps 15 degrees at 2000 ft AGL and that's when we got an aerodynamic 'rumble.' I initially thought spindle failure, but there was no roll and no pop. I thought it might be something just associated with flaps 15 degrees, so I called for flaps 30 degrees, with the modification, 'be ready to go back to 15 degrees.' the 'rumble' remained constant and the aircraft was very ctlable in that confign, so I just flew a few KTS fast, ready to execute a go around if needed. We did the before landing checklist and both confirmed the green light for the speed brakes (not in the down detent). The plane felt very normal down the GS, due to our light weight I assume, and the landing was smooth. The ground spoilers extended normally. I left the flaps down leaving the runway, knowing that an inspection would be required. I called dispatch and conferred with maintenance control. It wasn't until I was talking with them that I got the blood curdling thought of the speed brakes. I didn't remember retracting them when I lowered the flaps. I couldn't have been that stupid, could I? The more I thought about it, the more sense it made. I had left the speed brakes in the flight detent through the entire approach. I have lost a lot of sleep over this event. I have gone through my procedures, my mental trip wires, and my CRM techniques. It is so obvious, but at the time it wasn't. We were focused on the flaps (the symptom) the rest of the confign was lost. I can't tell you how embarrassed, ashamed and humble I am in submitting this report. Callback conversation with reporter revealed the following information: I discussed the installation of a white speed brake light on the forward first officer's panel. The reporter stated that he did not see a light while they had the speed brake extended and flaps out. When he examined his flight manuals, he found the B737-300 does not have the speed brake light as an alert that the speed brake is extended with flaps beyond 10 degrees while airborne. However, his company's B737-700 does have the light installed and it does perform that function.

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Original NASA ASRS Text

Title: B737-300 CREW MADE APCH AND LNDG WITH SPD BRAKES EXTENDED.

Narrative: ON APCH TO ZZZ1, WE WERE SET UP A LITTLE HIGH FROM ATC. WE WERE FINALLY CLRED FOR A VISUAL BEHIND ANOTHER CARRIER'S ACFT. I DEPLOYED THE SPD BRAKES TO NOT ONLY GET DOWN, BUT TO ALSO KEEP MY SPACING BEHIND THE ACFT. I WAS SPENDING A LOT OF TIME XCHKING MY ENERGY STATE, MY SPACING, AND MAINTAINING A VISUAL ON A SOMEWHAT UNFAMILIAR FIELD. I LOWERED THE LNDG GEAR AT 230 KTS FOLLOWED BY FLAPS 5 DEGS AT 210 KTS. I WAS ON GS WITH 5 MI TO GO. I WAS COMFORTABLE WITH MY ENERGY STATE AND EVERYTHING WAS COMING TOGETHER NICELY. I CALLED FOR FLAPS 15 DEGS AT 2000 FT AGL AND THAT'S WHEN WE GOT AN AERODYNAMIC 'RUMBLE.' I INITIALLY THOUGHT SPINDLE FAILURE, BUT THERE WAS NO ROLL AND NO POP. I THOUGHT IT MIGHT BE SOMETHING JUST ASSOCIATED WITH FLAPS 15 DEGS, SO I CALLED FOR FLAPS 30 DEGS, WITH THE MODIFICATION, 'BE READY TO GO BACK TO 15 DEGS.' THE 'RUMBLE' REMAINED CONSTANT AND THE ACFT WAS VERY CTLABLE IN THAT CONFIGN, SO I JUST FLEW A FEW KTS FAST, READY TO EXECUTE A GAR IF NEEDED. WE DID THE BEFORE LNDG CHKLIST AND BOTH CONFIRMED THE GREEN LIGHT FOR THE SPD BRAKES (NOT IN THE DOWN DETENT). THE PLANE FELT VERY NORMAL DOWN THE GS, DUE TO OUR LIGHT WT I ASSUME, AND THE LNDG WAS SMOOTH. THE GND SPOILERS EXTENDED NORMALLY. I LEFT THE FLAPS DOWN LEAVING THE RWY, KNOWING THAT AN INSPECTION WOULD BE REQUIRED. I CALLED DISPATCH AND CONFERRED WITH MAINT CTL. IT WASN'T UNTIL I WAS TALKING WITH THEM THAT I GOT THE BLOOD CURDLING THOUGHT OF THE SPD BRAKES. I DIDN'T REMEMBER RETRACTING THEM WHEN I LOWERED THE FLAPS. I COULDN'T HAVE BEEN THAT STUPID, COULD I? THE MORE I THOUGHT ABOUT IT, THE MORE SENSE IT MADE. I HAD LEFT THE SPD BRAKES IN THE FLT DETENT THROUGH THE ENTIRE APCH. I HAVE LOST A LOT OF SLEEP OVER THIS EVENT. I HAVE GONE THROUGH MY PROCS, MY MENTAL TRIP WIRES, AND MY CRM TECHNIQUES. IT IS SO OBVIOUS, BUT AT THE TIME IT WASN'T. WE WERE FOCUSED ON THE FLAPS (THE SYMPTOM) THE REST OF THE CONFIGN WAS LOST. I CAN'T TELL YOU HOW EMBARRASSED, ASHAMED AND HUMBLE I AM IN SUBMITTING THIS RPT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: I DISCUSSED THE INSTALLATION OF A WHITE SPD BRAKE LIGHT ON THE FORWARD FO'S PANEL. THE RPTR STATED THAT HE DID NOT SEE A LIGHT WHILE THEY HAD THE SPD BRAKE EXTENDED AND FLAPS OUT. WHEN HE EXAMINED HIS FLT MANUALS, HE FOUND THE B737-300 DOES NOT HAVE THE SPD BRAKE LIGHT AS AN ALERT THAT THE SPD BRAKE IS EXTENDED WITH FLAPS BEYOND 10 DEGS WHILE AIRBORNE. HOWEVER, HIS COMPANY'S B737-700 DOES HAVE THE LIGHT INSTALLED AND IT DOES PERFORM THAT FUNCTION.

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.