Narrative:

I am a fully qualified radar controller. I was working a cpr Y jet northbound to tpa. Cpr Y was south of fmy at FL220. Inbound to mia was air carrier X, descending from FL330 to 10000'. I recognized a potential conflict. I then cleared air carrier X to amend altitude and stop his descent at FL230. The pilot never replied. I then spoke with 2 or 3 of the other 8 aircraft that were on my frequency at the time. I went back to air carrier X to verify his assigned altitude when it was too late. Air carrier X missed his clearance and descended through the altitude of cpr X, proximity 1 mi latitude, less than 200' vertical. After reviewing the tapes, it is clear that the clearance was issued and there was no interference. I feel that the pilots should pay more attention to ATC and listen up. I've been in the cockpit before to realize that pilots don't always take the radio as seriously as they should. Supplemental information from acn 176473: we were cleared by ZMA for the collier 1 arrival via direct collier with pilot's discretion to FL240 and to maintain 280 KTS in the descent. Approximately 30 mi northwest of the collier county VOR, we began the descent and checked out of FL330, at which time we were told to descend to FL210 and to cross the phenx intersection at 10000' and 250 KTS. The next xmissions from ZMA was received when we were southeast of the collier county VOR and approximately 40 mi from the phenx intersection passing through FL217. When center asked if we were maintaining FL230, we replied, 'negative, we are at 21.4 and descending so as to phenx at 10000' as previously cleared.' the controller replied that he had asked us to stop our descent at FL230. None of the 3 pilots in our cockpit had heard or acknowledged with a readback this transmission. Apparently cpr Y had turned into our descent path and the controller was trying to prevent a collision. We were asked, as was the cpr Y, to call center on the ground. A review of the ATC tapes confirmed that we did not acknowledge receipt of the level off at FL230.

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Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM CPR Y. SYSTEM ERROR.

Narrative: I AM A FULLY QUALIFIED RADAR CTLR. I WAS WORKING A CPR Y JET NBND TO TPA. CPR Y WAS S OF FMY AT FL220. INBND TO MIA WAS ACR X, DSNDING FROM FL330 TO 10000'. I RECOGNIZED A POTENTIAL CONFLICT. I THEN CLRED ACR X TO AMEND ALT AND STOP HIS DSNT AT FL230. THE PLT NEVER REPLIED. I THEN SPOKE WITH 2 OR 3 OF THE OTHER 8 ACFT THAT WERE ON MY FREQ AT THE TIME. I WENT BACK TO ACR X TO VERIFY HIS ASSIGNED ALT WHEN IT WAS TOO LATE. ACR X MISSED HIS CLRNC AND DSNDED THROUGH THE ALT OF CPR X, PROX 1 MI LAT, LESS THAN 200' VERT. AFTER REVIEWING THE TAPES, IT IS CLR THAT THE CLRNC WAS ISSUED AND THERE WAS NO INTERFERENCE. I FEEL THAT THE PLTS SHOULD PAY MORE ATTN TO ATC AND LISTEN UP. I'VE BEEN IN THE COCKPIT BEFORE TO REALIZE THAT PLTS DON'T ALWAYS TAKE THE RADIO AS SERIOUSLY AS THEY SHOULD. SUPPLEMENTAL INFO FROM ACN 176473: WE WERE CLRED BY ZMA FOR THE COLLIER 1 ARR VIA DIRECT COLLIER WITH PLT'S DISCRETION TO FL240 AND TO MAINTAIN 280 KTS IN THE DSNT. APPROX 30 MI NW OF THE COLLIER COUNTY VOR, WE BEGAN THE DSNT AND CHKED OUT OF FL330, AT WHICH TIME WE WERE TOLD TO DSND TO FL210 AND TO CROSS THE PHENX INTXN AT 10000' AND 250 KTS. THE NEXT XMISSIONS FROM ZMA WAS RECEIVED WHEN WE WERE SE OF THE COLLIER COUNTY VOR AND APPROX 40 MI FROM THE PHENX INTXN PASSING THROUGH FL217. WHEN CENTER ASKED IF WE WERE MAINTAINING FL230, WE REPLIED, 'NEGATIVE, WE ARE AT 21.4 AND DSNDING SO AS TO PHENX AT 10000' AS PREVIOUSLY CLRED.' THE CTLR REPLIED THAT HE HAD ASKED US TO STOP OUR DSNT AT FL230. NONE OF THE 3 PLTS IN OUR COCKPIT HAD HEARD OR ACKNOWLEDGED WITH A READBACK THIS XMISSION. APPARENTLY CPR Y HAD TURNED INTO OUR DSNT PATH AND THE CTLR WAS TRYING TO PREVENT A COLLISION. WE WERE ASKED, AS WAS THE CPR Y, TO CALL CENTER ON THE GND. A REVIEW OF THE ATC TAPES CONFIRMED THAT WE DID NOT ACKNOWLEDGE RECEIPT OF THE LEVEL OFF AT FL230.

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.