Narrative:

Relatively recently, as a result of the B737 rudder problem, aircraft maneuvering speeds have been increased by as much as 20 KTS. So, a heavy B737-400, e.g., 119000 pounds, has a minimum maneuvering speed of 180 KTS at flaps 10 degrees, to fly any slower would require that the landing gear be extended prior to any flap setting greater than 10 degrees of flap being selected (or the gear warning sounds continuously and cannot be silenced). Tonight, upon being vectored for an ILS approach to runway 36L at ZZZ, we were instructed to slow to 170 KTS, while more than 20 mi from the airport. We requested to maintain our minimum 'clean,' flaps up maneuver speed of 230 KTS (until within 20 mi of the airport). The controller acknowledged our request and vectored us further out to allow for more spacing. Upon being turned over to the final approach controller, still 26 mi from the airport, on a left base leg for runway 36L, we were again instructed to slow to 170 KTS. We advised the controller that our minimum maneuver speed would be 180 KTS until within 10 mi of the airport (the point that it would be somewhat realistic to put the landing gear down, and then additional flap, allowing a slower speed). The controller could not understand why we did not wish to fly at 25 mi from the airport, with the landing gear down at flaps 15 degrees and 170 KTS. It is important to note, that there was a 22 KT tailwind on the approach all the way down to an altitude of 400 ft AGL with a 5 KT tailwind at the 50 ft crossing height. No wonder that ATC had a 25 mi final approach course with traffic slowed to 170 KTS/KIAS, 25 mi from touchdown! We were at close to our maximum landing weight too. This was a major distraction (controller badgering) to me, and increased my workload. We did slow to 180 KTS, 25 mi from the airport at flaps 10 degrees, we were unable to fly any slower, as we would have had to extend the landing gear 25 mi from the airport. Pilot concurrence is required to slow below 210 KTS when greater than 20 mi from the airport. I would much rather be taken out further on a vector for spacing, or hold, than to have a jet transport fully configured for landing, more than 25 mi from the airport. Also, ZZZ approach controller likes to issue specific speed assignments, after an approach clearance is issued, when speed is then supposed to be at pilot discretion, unless the speed assignment is with pilot concurrence! I am recommending that an awareness program for ATC controllers be initiated regarding increased B737 maneuver speeds, particularly at high aircraft gross weights. Callback conversation with reporter indicates that the aircraft manufacturer has recommended an increase in minimum maneuvering speeds. The B737-300 and subsequent models also utilize 15 degrees flaps as a landing flap setting. This is the reason for activating the continuous warning horn at any flap setting above flaps 10 degrees. Reporter states about 60 percent of the controllers know of the increased speed requirement of the B737. Those that don't know, seem not to accept crew word that they are unable to slow below 180 KTS.

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Original NASA ASRS Text

Title: B737. THE ADDITION OF 20 KTS MINIMUM FLAP MANEUVERING SPDS RESTRICTS THE B737 TO A MINIMUM SPD OF 180 KTS.

Narrative: RELATIVELY RECENTLY, AS A RESULT OF THE B737 RUDDER PROB, ACFT MANEUVERING SPDS HAVE BEEN INCREASED BY AS MUCH AS 20 KTS. SO, A HEAVY B737-400, E.G., 119000 POUNDS, HAS A MINIMUM MANEUVERING SPD OF 180 KTS AT FLAPS 10 DEGS, TO FLY ANY SLOWER WOULD REQUIRE THAT THE LNDG GEAR BE EXTENDED PRIOR TO ANY FLAP SETTING GREATER THAN 10 DEGS OF FLAP BEING SELECTED (OR THE GEAR WARNING SOUNDS CONTINUOUSLY AND CANNOT BE SILENCED). TONIGHT, UPON BEING VECTORED FOR AN ILS APCH TO RWY 36L AT ZZZ, WE WERE INSTRUCTED TO SLOW TO 170 KTS, WHILE MORE THAN 20 MI FROM THE ARPT. WE REQUESTED TO MAINTAIN OUR MINIMUM 'CLEAN,' FLAPS UP MANEUVER SPD OF 230 KTS (UNTIL WITHIN 20 MI OF THE ARPT). THE CTLR ACKNOWLEDGED OUR REQUEST AND VECTORED US FURTHER OUT TO ALLOW FOR MORE SPACING. UPON BEING TURNED OVER TO THE FINAL APCH CTLR, STILL 26 MI FROM THE ARPT, ON A L BASE LEG FOR RWY 36L, WE WERE AGAIN INSTRUCTED TO SLOW TO 170 KTS. WE ADVISED THE CTLR THAT OUR MINIMUM MANEUVER SPD WOULD BE 180 KTS UNTIL WITHIN 10 MI OF THE ARPT (THE POINT THAT IT WOULD BE SOMEWHAT REALISTIC TO PUT THE LNDG GEAR DOWN, AND THEN ADDITIONAL FLAP, ALLOWING A SLOWER SPD). THE CTLR COULD NOT UNDERSTAND WHY WE DID NOT WISH TO FLY AT 25 MI FROM THE ARPT, WITH THE LNDG GEAR DOWN AT FLAPS 15 DEGS AND 170 KTS. IT IS IMPORTANT TO NOTE, THAT THERE WAS A 22 KT TAILWIND ON THE APCH ALL THE WAY DOWN TO AN ALT OF 400 FT AGL WITH A 5 KT TAILWIND AT THE 50 FT CROSSING HEIGHT. NO WONDER THAT ATC HAD A 25 MI FINAL APCH COURSE WITH TFC SLOWED TO 170 KTS/KIAS, 25 MI FROM TOUCHDOWN! WE WERE AT CLOSE TO OUR MAX LNDG WEIGHT TOO. THIS WAS A MAJOR DISTRACTION (CTLR BADGERING) TO ME, AND INCREASED MY WORKLOAD. WE DID SLOW TO 180 KTS, 25 MI FROM THE ARPT AT FLAPS 10 DEGS, WE WERE UNABLE TO FLY ANY SLOWER, AS WE WOULD HAVE HAD TO EXTEND THE LNDG GEAR 25 MI FROM THE ARPT. PLT CONCURRENCE IS REQUIRED TO SLOW BELOW 210 KTS WHEN GREATER THAN 20 MI FROM THE ARPT. I WOULD MUCH RATHER BE TAKEN OUT FURTHER ON A VECTOR FOR SPACING, OR HOLD, THAN TO HAVE A JET TRANSPORT FULLY CONFIGURED FOR LNDG, MORE THAN 25 MI FROM THE ARPT. ALSO, ZZZ APCH CTLR LIKES TO ISSUE SPECIFIC SPD ASSIGNMENTS, AFTER AN APCH CLRNC IS ISSUED, WHEN SPD IS THEN SUPPOSED TO BE AT PLT DISCRETION, UNLESS THE SPD ASSIGNMENT IS WITH PLT CONCURRENCE! I AM RECOMMENDING THAT AN AWARENESS PROGRAM FOR ATC CONTROLLERS BE INITIATED REGARDING INCREASED B737 MANEUVER SPDS, PARTICULARLY AT HIGH ACFT GROSS WEIGHTS. CALLBACK CONVERSATION WITH RPTR INDICATES THAT THE ACFT MANUFACTURER HAS RECOMMENDED AN INCREASE IN MINIMUM MANEUVERING SPDS. THE B737-300 AND SUBSEQUENT MODELS ALSO UTILIZE 15 DEGS FLAPS AS A LNDG FLAP SETTING. THIS IS THE REASON FOR ACTIVATING THE CONTINUOUS WARNING HORN AT ANY FLAP SETTING ABOVE FLAPS 10 DEGS. RPTR STATES ABOUT 60 PERCENT OF THE CTLRS KNOW OF THE INCREASED SPD REQUIREMENT OF THE B737. THOSE THAT DON'T KNOW, SEEM NOT TO ACCEPT CREW WORD THAT THEY ARE UNABLE TO SLOW BELOW 180 KTS.

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.