MD80 and B737, opposite direction, take evasive action when MD80 reads back incorrect descent altitude, which ZKC controllers do not catch until both aircraft initiate TCASII action.

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Attributes
ACN	469209
Time
Date	200004
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : bum.vortac
State Reference	MO
Altitude	msl bound lower : 26500 msl bound upper : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zkc.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Route In Use	arrival star : trake
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zkc.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 17 controller radar : 15.5 controller time certified in position1 : 13.5
ASRS Report	469209
Person 2
Affiliation	government : faa
Function	controller : handoff position
Qualification	pilot : instrument
Experience	controller radar : 18 flight time total : 5000
ASRS Report	469210
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	horizontal : 17400 vertical : 300
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Descended air carrier X to FL290. Air carrier Y was at FL280. Air carrier X read back that they were out of FL330 for FL240. Radios were scratchy, I missed the readback. The sector was very complex at the time. I had numerous aircraft on vectors for spacing for st louis. By the time I was aware that air carrier X had descended into air carrier Y's altitude, the aircraft had already responded to TCASII. Conflict alert did not activate until after the error occurred. The best way to help controllers with these types of errors, would be to make pilots accountable for listening to control instructions. It would give them more incentive to pay attention -- be a team player. Supplemental information from acn 460210: aircraft #2 was wbound at FL280. Aircraft #1 eastbound on trake 8 STAR was descended from FL330 to FL290. Pilot read back 'FL240' and descended into aircraft #2's altitude. Both aircraft responded to RA's. Supplemental information from acn 469760: I was the first officer (PF) on air carrier X from phx to stl. When we were approximately 100 mi west of bum at FL330, ZKC cleared us to FL240. At around FL265, we received a TCASII RA instructing us to climb for an aircraft ahead and 800-1000 ft below us. We climbed back up to about FL280. ZKC asked us why we did not level at FL290. The captain advised them we were cleared to FL240.

Original NASA ASRS Text

Title: MD80 AND B737, OPPOSITE DIRECTION, TAKE EVASIVE ACTION WHEN MD80 READS BACK INCORRECT DSCNT ALT, WHICH ZKC CTLRS DO NOT CATCH UNTIL BOTH ACFT INITIATE TCASII ACTION.

Narrative: DSNDED ACR X TO FL290. ACR Y WAS AT FL280. ACR X READ BACK THAT THEY WERE OUT OF FL330 FOR FL240. RADIOS WERE SCRATCHY, I MISSED THE READBACK. THE SECTOR WAS VERY COMPLEX AT THE TIME. I HAD NUMEROUS ACFT ON VECTORS FOR SPACING FOR ST LOUIS. BY THE TIME I WAS AWARE THAT ACR X HAD DSNDED INTO ACR Y'S ALT, THE ACFT HAD ALREADY RESPONDED TO TCASII. CONFLICT ALERT DID NOT ACTIVATE UNTIL AFTER THE ERROR OCCURRED. THE BEST WAY TO HELP CTLRS WITH THESE TYPES OF ERRORS, WOULD BE TO MAKE PLTS ACCOUNTABLE FOR LISTENING TO CTL INSTRUCTIONS. IT WOULD GIVE THEM MORE INCENTIVE TO PAY ATTN -- BE A TEAM PLAYER. SUPPLEMENTAL INFO FROM ACN 460210: ACFT #2 WAS WBOUND AT FL280. ACFT #1 EBOUND ON TRAKE 8 STAR WAS DSNDED FROM FL330 TO FL290. PLT READ BACK 'FL240' AND DSNDED INTO ACFT #2'S ALT. BOTH ACFT RESPONDED TO RA'S. SUPPLEMENTAL INFO FROM ACN 469760: I WAS THE FO (PF) ON ACR X FROM PHX TO STL. WHEN WE WERE APPROX 100 MI W OF BUM AT FL330, ZKC CLRED US TO FL240. AT AROUND FL265, WE RECEIVED A TCASII RA INSTRUCTING US TO CLB FOR AN ACFT AHEAD AND 800-1000 FT BELOW US. WE CLBED BACK UP TO ABOUT FL280. ZKC ASKED US WHY WE DID NOT LEVEL AT FL290. THE CAPT ADVISED THEM WE WERE CLRED TO FL240.

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.