Air carrier a took a clearance meant for air carrier B and left TRACON frequency. Conflict resulted.

Attributes
ACN	195078
Time
Date	199111
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mbs
State Reference	MI
Altitude	msl bound lower : 10000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : mbs
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
ASRS Report	195078
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 20000 flight time type : 10000
ASRS Report	194783
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence other
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error other

Narrative:

The situation occurred between air carrier uzu, inbound from the southeast of saginaw descending out of 12500 for 4000 and mdt departing saginaw for yzr (southeast) climbing out of 3000 fot 10000. The air carrier uzu flight was issued a heading of 345 degrees radar vectors for traffic and his descent. There was an air carrier uzi flight (departure of mbs) 7 mi south of the airport climbing to 8000 for traffic at 9000. There was a lot of frequency congestion and once air carrier uzi had passed the traffic, he was climbed to 100 and changed over to cleveland center. I started to listen to the readback which stated 126.75 cleveland center air carrier. Then I had to coordinate with center and turn an medium large transport into the ILS 23 approach. Then I went and issued a left turn (260) to air carrier uzu rv for descent and restated to maintain 4000. There was no reply. I reattempted to turn air carrier uzu with no reply. I then instructed mdt to turn left 050 degree rv around traffic. There was no reply from the mdt. I then issued a TA to the mdt, still no reply. I then issued a TA to air carrier uzu, told the aircraft to turn left immediately to maintain 4000, expedite your descent, traffic 12 O'clock, 2 mi, same altitude. Air carrier uzu finally replied ok air carrier uzu. I then asked mdt are you still on frequency and he replied yes sir and we had the traffic that passed off our left. The air carrier was cleared 13000 and changed to the center. I feel the situation occurred due to several circumstances. The missed readback by me with air carrier uzu. The pilots of air carrier uzu taking the frequency for air carrier uzi. Air carrier uzu was off frequency for 57 seconds. Frequency congestion and the fact that mdt doesn't reply for 37 seconds. The pilot of mdt later stated that I was being blocked. Also the scheduling of an air carrier uzu, air carrier uzi and air carrier B eeu at the same time. I believe the FAA continued training on ensuring readbacks will help eliminate situations like this from occurring. Training for both pilots and controllers.

Original NASA ASRS Text

Title: ACR A TOOK A CLRNC MEANT FOR ACR B AND LEFT TRACON FREQ. CONFLICT RESULTED.

Narrative: THE SITUATION OCCURRED BTWN ACR UZU, INBOUND FROM THE SE OF SAGINAW DSNDING OUT OF 12500 FOR 4000 AND MDT DEPARTING SAGINAW FOR YZR (SE) CLBING OUT OF 3000 FOT 10000. THE ACR UZU FLT WAS ISSUED A HDG OF 345 DEGS RADAR VECTORS FOR TFC AND HIS DSCNT. THERE WAS AN ACR UZI FLT (DEP OF MBS) 7 MI S OF THE ARPT CLBING TO 8000 FOR TFC AT 9000. THERE WAS A LOT OF FREQ CONGESTION AND ONCE ACR UZI HAD PASSED THE TFC, HE WAS CLBED TO 100 AND CHANGED OVER TO CLEVELAND CENTER. I STARTED TO LISTEN TO THE READBACK WHICH STATED 126.75 CLEVELAND CENTER ACR. THEN I HAD TO COORDINATE WITH CENTER AND TURN AN MLG INTO THE ILS 23 APCH. THEN I WENT AND ISSUED A L TURN (260) TO ACR UZU RV FOR DSCNT AND RESTATED TO MAINTAIN 4000. THERE WAS NO REPLY. I REATTEMPTED TO TURN ACR UZU WITH NO REPLY. I THEN INSTRUCTED MDT TO TURN L 050 DEG RV AROUND TFC. THERE WAS NO REPLY FROM THE MDT. I THEN ISSUED A TA TO THE MDT, STILL NO REPLY. I THEN ISSUED A TA TO ACR UZU, TOLD THE ACFT TO TURN L IMMEDIATELY TO MAINTAIN 4000, EXPEDITE YOUR DSCNT, TFC 12 O'CLOCK, 2 MI, SAME ALT. ACR UZU FINALLY REPLIED OK ACR UZU. I THEN ASKED MDT ARE YOU STILL ON FREQ AND HE REPLIED YES SIR AND WE HAD THE TFC THAT PASSED OFF OUR L. THE ACR WAS CLRED 13000 AND CHANGED TO THE CENTER. I FEEL THE SITUATION OCCURRED DUE TO SEVERAL CIRCUMSTANCES. THE MISSED READBACK BY ME WITH ACR UZU. THE PLTS OF ACR UZU TAKING THE FREQ FOR ACR UZI. ACR UZU WAS OFF FREQ FOR 57 SECONDS. FREQ CONGESTION AND THE FACT THAT MDT DOESN'T REPLY FOR 37 SECONDS. THE PLT OF MDT LATER STATED THAT I WAS BEING BLOCKED. ALSO THE SCHEDULING OF AN ACR UZU, ACR UZI AND ACR B EEU AT THE SAME TIME. I BELIEVE THE FAA CONTINUED TRAINING ON ENSURING READBACKS WILL HELP ELIMINATE SITUATIONS LIKE THIS FROM OCCURRING. TRAINING FOR BOTH PLTS AND CTLRS.

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.