Narrative:

Cleared for the ILS runway 9R, we were told to maintain 4000 ft until tizzy (10.7 DME out) and, we thought, a speed of 170 KTS to tizzy. I was watching the TCASII and could see spacing on final was critical. Passing tizzy, the captain began calling for configuring the aircraft. By the time we were nearing burny (6.4 DME out), we were fully configured. Tower called and asked our current speed. I replied '130 KTS.' tower asked 'is that what you were assigned?' I replied 'we were assigned 170 to tizzy.' tower said 'that's not going to work. I need you to pick it back up.' we increased to 170 KTS for approximately 1 min, then tower told us we could slow again. Landed without incident. I believe we were probably assigned 170 KTS to burny, and either misheard, or the controller misspoke. This is due to the fact that when being cleared for an instrument approach, the controllers usually issue 3 or 4 simultaneous commands, when it has been proven that more than 2 concurrent instructions lead to errors in communication. Our normal DC9's have 40 degree landing flaps. This particular one had 50 degrees, which makes it slow much more rapidly. Captain didn't seem aware of spacing issue. I should have questioned his configuring the aircraft when he did. Our training program for an autoplt-coupled approach (which this was) calls for configuring rather early in the approach. This is fine in the training environment, but is actually bad practice in the environment we normally operate in (atlanta), where speed and spacing are so critical.

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Original NASA ASRS Text

Title: A DC9 FLC IS UNSURE AS TO WHETHER THEY DEVIATED FROM ATC SPD RESTR OR WHETHER THE CTLR, WHO WAS OVERLOADED, SIMPLY MISSPOKE. ATL, GA.

Narrative: CLRED FOR THE ILS RWY 9R, WE WERE TOLD TO MAINTAIN 4000 FT UNTIL TIZZY (10.7 DME OUT) AND, WE THOUGHT, A SPD OF 170 KTS TO TIZZY. I WAS WATCHING THE TCASII AND COULD SEE SPACING ON FINAL WAS CRITICAL. PASSING TIZZY, THE CAPT BEGAN CALLING FOR CONFIGURING THE ACFT. BY THE TIME WE WERE NEARING BURNY (6.4 DME OUT), WE WERE FULLY CONFIGURED. TWR CALLED AND ASKED OUR CURRENT SPD. I REPLIED '130 KTS.' TWR ASKED 'IS THAT WHAT YOU WERE ASSIGNED?' I REPLIED 'WE WERE ASSIGNED 170 TO TIZZY.' TWR SAID 'THAT'S NOT GOING TO WORK. I NEED YOU TO PICK IT BACK UP.' WE INCREASED TO 170 KTS FOR APPROX 1 MIN, THEN TWR TOLD US WE COULD SLOW AGAIN. LANDED WITHOUT INCIDENT. I BELIEVE WE WERE PROBABLY ASSIGNED 170 KTS TO BURNY, AND EITHER MISHEARD, OR THE CTLR MISSPOKE. THIS IS DUE TO THE FACT THAT WHEN BEING CLRED FOR AN INST APCH, THE CTLRS USUALLY ISSUE 3 OR 4 SIMULTANEOUS COMMANDS, WHEN IT HAS BEEN PROVEN THAT MORE THAN 2 CONCURRENT INSTRUCTIONS LEAD TO ERRORS IN COM. OUR NORMAL DC9'S HAVE 40 DEG LNDG FLAPS. THIS PARTICULAR ONE HAD 50 DEGS, WHICH MAKES IT SLOW MUCH MORE RAPIDLY. CAPT DIDN'T SEEM AWARE OF SPACING ISSUE. I SHOULD HAVE QUESTIONED HIS CONFIGURING THE ACFT WHEN HE DID. OUR TRAINING PROGRAM FOR AN AUTOPLT-COUPLED APCH (WHICH THIS WAS) CALLS FOR CONFIGURING RATHER EARLY IN THE APCH. THIS IS FINE IN THE TRAINING ENVIRONMENT, BUT IS ACTUALLY BAD PRACTICE IN THE ENVIRONMENT WE NORMALLY OPERATE IN (ATLANTA), WHERE SPD AND SPACING ARE SO CRITICAL.

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.