Narrative:

Upon departing MSL I received my clearance on the ground from MSL FSS. The clearance read 'cleared to depart runway 11 on course, maintain 13000', departure on 120.8, squawk 1634.' I read back and it was correct. I departed, contacted memphis center on 120.8, received radar contact. A lady controller was working at the time. Also there seemed to be a lot of backgnd noise in her xmissions (laughing). I was cleared to FL210 and acknowledged by reading back 'up to FL210.' after passing 11500', controller said 'did you know you were cleared to 11000'?' I told her that I was cleared to FL210. She gave a turn to 040 degree. I questioned her and she said to turn to 180 degree. I reported that I was going to level at 11000' heading 180 degree. Center didn't reply. I called back, still no reply. I said 'memphis center do you read nxxxxx?' still no reply. I called again and they said 'cleared on course.' the rest of the flight was completed with no incident. The purpose of the readback of a clearance is to assure the pilot understands what the controller said. In this case, my clearance to FL210 was read back and center never said it was incorrect. So I continued to climb until center called back. I don't think center controllers should ignore a call from an aircraft, especially if a possible traffic conflict exists.

Google
 

Original NASA ASRS Text

Title: CORP ACFT PLT READS BACK CLRNC WITH NO RESPONSE. SHORTLY TOLD CLRNC FOR 11000' NOT FL210 AS READ BACK.

Narrative: UPON DEPARTING MSL I RECEIVED MY CLRNC ON THE GND FROM MSL FSS. THE CLRNC READ 'CLRED TO DEPART RWY 11 ON COURSE, MAINTAIN 13000', DEP ON 120.8, SQUAWK 1634.' I READ BACK AND IT WAS CORRECT. I DEPARTED, CONTACTED MEMPHIS CTR ON 120.8, RECEIVED RADAR CONTACT. A LADY CTLR WAS WORKING AT THE TIME. ALSO THERE SEEMED TO BE A LOT OF BACKGND NOISE IN HER XMISSIONS (LAUGHING). I WAS CLRED TO FL210 AND ACKNOWLEDGED BY READING BACK 'UP TO FL210.' AFTER PASSING 11500', CTLR SAID 'DID YOU KNOW YOU WERE CLRED TO 11000'?' I TOLD HER THAT I WAS CLRED TO FL210. SHE GAVE A TURN TO 040 DEG. I QUESTIONED HER AND SHE SAID TO TURN TO 180 DEG. I RPTED THAT I WAS GOING TO LEVEL AT 11000' HDG 180 DEG. CTR DIDN'T REPLY. I CALLED BACK, STILL NO REPLY. I SAID 'MEMPHIS CTR DO YOU READ NXXXXX?' STILL NO REPLY. I CALLED AGAIN AND THEY SAID 'CLRED ON COURSE.' THE REST OF THE FLT WAS COMPLETED WITH NO INCIDENT. THE PURPOSE OF THE READBACK OF A CLRNC IS TO ASSURE THE PLT UNDERSTANDS WHAT THE CTLR SAID. IN THIS CASE, MY CLRNC TO FL210 WAS READ BACK AND CTR NEVER SAID IT WAS INCORRECT. SO I CONTINUED TO CLB UNTIL CTR CALLED BACK. I DON'T THINK CTR CTLRS SHOULD IGNORE A CALL FROM AN ACFT, ESPECIALLY IF A POSSIBLE TFC CONFLICT EXISTS.

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.