Narrative:

While working the local control #1 (LC1) position last week; I experienced several instances where separation was going to be lost in the final approach course to runway 36R. Unfortunately; I was unable to write the call signs down due to how busy the position was at the time of these incidents. Mem was in a north confign during our noon arrival push. We were landing runways 36L and 36R. Final monitors were up and operational. Due to the low ceilings and visibility; I was unable to see any runway 36L arrs until they were approximately 1/2 mi final. Visual separation could not be applied between successive arrs; and I was required to ask arriving aircraft to 'expedite' off of the runway; or to 'turn right as soon as possible' in order to allow the next arrival to land without incident. As the arrival push progressed; several heavy jets were sequenced to my runway. Wind reports on the surface indicated 10 KT headwinds; and this increased slightly for every 1000 ft based on PIREPS. Compression was a serious issue; as was evident by observing how 5 mi radar separation at the step-down fixes would decrease to 2.5-3.0 mi at the threshold with like-type large aircraft. When the heavy jets started to check onto my frequency with 4-6 mi of spacing depending on the type of aircraft that was following the heavy; I knew that the assigned speeds and spacing would not work. Mem local procedures mandate that the final monitors are responsible for the separation on final until 1 mi from the runway or until the tower can provide visual separation. There were at least 4 instances where separation was in process of being lost; and I asked the following aircraft to 'say speed' in an effort to give the final monitor a hint of what was happening. The final monitor always took the hint; and began reducing the speed of the trailing aircraft; but in the end; it was always too late. On 2 instances I took the initiative and simply canceled the approach clearance of the aircraft that was following the heavy jet; and then asked the cabin attendant coordinator to coordinate a heading and altitude with the appropriate radar sector downstairs.

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Original NASA ASRS Text

Title: MEM LCL CTLR DESCRIBED INCIDENT INVOLVING SIMULTANEOUS APCH PROCS TO RWY 36L-R WHEN SEPARATION WAS LOST AND GAR WAS REQUIRED.

Narrative: WHILE WORKING THE LCL CTL #1 (LC1) POS LAST WK; I EXPERIENCED SEVERAL INSTANCES WHERE SEPARATION WAS GOING TO BE LOST IN THE FINAL APCH COURSE TO RWY 36R. UNFORTUNATELY; I WAS UNABLE TO WRITE THE CALL SIGNS DOWN DUE TO HOW BUSY THE POS WAS AT THE TIME OF THESE INCIDENTS. MEM WAS IN A N CONFIGN DURING OUR NOON ARR PUSH. WE WERE LNDG RWYS 36L AND 36R. FINAL MONITORS WERE UP AND OPERATIONAL. DUE TO THE LOW CEILINGS AND VISIBILITY; I WAS UNABLE TO SEE ANY RWY 36L ARRS UNTIL THEY WERE APPROX 1/2 MI FINAL. VISUAL SEPARATION COULD NOT BE APPLIED BTWN SUCCESSIVE ARRS; AND I WAS REQUIRED TO ASK ARRIVING ACFT TO 'EXPEDITE' OFF OF THE RWY; OR TO 'TURN R ASAP' IN ORDER TO ALLOW THE NEXT ARR TO LAND WITHOUT INCIDENT. AS THE ARR PUSH PROGRESSED; SEVERAL HVY JETS WERE SEQUENCED TO MY RWY. WIND RPTS ON THE SURFACE INDICATED 10 KT HEADWINDS; AND THIS INCREASED SLIGHTLY FOR EVERY 1000 FT BASED ON PIREPS. COMPRESSION WAS A SERIOUS ISSUE; AS WAS EVIDENT BY OBSERVING HOW 5 MI RADAR SEPARATION AT THE STEP-DOWN FIXES WOULD DECREASE TO 2.5-3.0 MI AT THE THRESHOLD WITH LIKE-TYPE LARGE ACFT. WHEN THE HVY JETS STARTED TO CHK ONTO MY FREQ WITH 4-6 MI OF SPACING DEPENDING ON THE TYPE OF ACFT THAT WAS FOLLOWING THE HVY; I KNEW THAT THE ASSIGNED SPDS AND SPACING WOULD NOT WORK. MEM LCL PROCS MANDATE THAT THE FINAL MONITORS ARE RESPONSIBLE FOR THE SEPARATION ON FINAL UNTIL 1 MI FROM THE RWY OR UNTIL THE TWR CAN PROVIDE VISUAL SEPARATION. THERE WERE AT LEAST 4 INSTANCES WHERE SEPARATION WAS IN PROCESS OF BEING LOST; AND I ASKED THE FOLLOWING ACFT TO 'SAY SPD' IN AN EFFORT TO GIVE THE FINAL MONITOR A HINT OF WHAT WAS HAPPENING. THE FINAL MONITOR ALWAYS TOOK THE HINT; AND BEGAN REDUCING THE SPD OF THE TRAILING ACFT; BUT IN THE END; IT WAS ALWAYS TOO LATE. ON 2 INSTANCES I TOOK THE INITIATIVE AND SIMPLY CANCELED THE APCH CLRNC OF THE ACFT THAT WAS FOLLOWING THE HVY JET; AND THEN ASKED THE CAB COORDINATOR TO COORDINATE A HDG AND ALT WITH THE APPROPRIATE RADAR SECTOR DOWNSTAIRS.

Data retrieved from NASA's ASRS site as of January 2009 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.