Narrative:

After frequency change from tulsa departure control to kansas city center, air carrier X received and acknowledged clearance to 16000 ft. Controller working more than 1 frequency and very busy, climbing out rapidly at ATC assigned speed of 250 KTS. Approaching 14000 ft requested and received clearance to FL230, verified by copilot and entered into altitude alert system window. At 16000 ft noticed traffic at 17000 ft on TCASII, spotted aircraft visually, TA warning only on TCASII, told copilot to level off which he was in the process of doing when ATC requested us to confirm level at 16000 ft. Responded, returning to 16000 ft per ATC request. Cause of problem: controller working more than 1 frequency. They should be restr to 1 frequency only. Supplemental information from acn 188979: I was first officer on air carrier X from tul to den. Air carrier X was light (141300 pounds). I was flying and climbing at 250 KTS per departure control instructions giving us a good climb rate. Our initial climb was to 4000 ft per departure clearance with an expect FL240 within 10 mins. Passing approximately 13000 ft departure gave us clearance to 16000 ft and a frequency change to center. After switching frequencys it was rather busy with the controller handling what appeared to be at least 1 other frequency and military traffic, as several transmissions were blocked and repeated. The captain checked in with center whom subsequently cleared us to FL230. The captain set in 230 in the altitude alert and I verified FL230. Approaching 16000 ft center pointed out traffic at 11 O'clock and (around 12-15 mi) at 17000 ft. The captain picked up the traffic visually very quickly and pointed him out. I first looked at the TCASII, which was in the RA mode, and then observed the traffic visually. I remember thinking that it seemed a little odd to be climbing through his altitude with only 4-5 mi horizontal separation without us acknowledging that we had him visually first. I didn't feel we were in danger at any time. The captain signaled to me visually to level off, as he was thinking the same as I. I made a slow level off which took a few hundred ft due to our climb rate. The maximum altitude I recall was approximately 16400 ft. A few seconds after the captain signaled me to level off, ATC asked us to verify our altitude. The captain responded that we were descending through 16400 down to 16000 ft. At about that time we received a 'traffic, traffic' alert from TCASII, which was in the RA mode. At no time did we receive an RA command! After passing the traffic ATC cleared us to climb again. A few mins later ATC asked us to call them from den. The 3 things that stick in my mind and that I am positively sure about is that: 1) ATC was handling more than 1 frequency. 2) the captain acknowledged and set in FL230 into the altitude alert window. 3) I verbally acknowledged it.

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Original NASA ASRS Text

Title: ACR X NON ADHERENCE TO ATC CLRNC HAD LTSS FROM ACFT Y. PLTDEV.

Narrative: AFTER FREQ CHANGE FROM TULSA DEP CTL TO KANSAS CITY CENTER, ACR X RECEIVED AND ACKNOWLEDGED CLRNC TO 16000 FT. CTLR WORKING MORE THAN 1 FREQ AND VERY BUSY, CLBING OUT RAPIDLY AT ATC ASSIGNED SPD OF 250 KTS. APCHING 14000 FT REQUESTED AND RECEIVED CLRNC TO FL230, VERIFIED BY COPLT AND ENTERED INTO ALT ALERT SYS WINDOW. AT 16000 FT NOTICED TFC AT 17000 FT ON TCASII, SPOTTED ACFT VISUALLY, TA WARNING ONLY ON TCASII, TOLD COPLT TO LEVEL OFF WHICH HE WAS IN THE PROCESS OF DOING WHEN ATC REQUESTED US TO CONFIRM LEVEL AT 16000 FT. RESPONDED, RETURNING TO 16000 FT PER ATC REQUEST. CAUSE OF PROBLEM: CTLR WORKING MORE THAN 1 FREQ. THEY SHOULD BE RESTR TO 1 FREQ ONLY. SUPPLEMENTAL INFO FROM ACN 188979: I WAS FO ON ACR X FROM TUL TO DEN. ACR X WAS LIGHT (141300 POUNDS). I WAS FLYING AND CLBING AT 250 KTS PER DEP CTL INSTRUCTIONS GIVING US A GOOD CLB RATE. OUR INITIAL CLB WAS TO 4000 FT PER DEP CLRNC WITH AN EXPECT FL240 WITHIN 10 MINS. PASSING APPROX 13000 FT DEP GAVE US CLRNC TO 16000 FT AND A FREQ CHANGE TO CENTER. AFTER SWITCHING FREQS IT WAS RATHER BUSY WITH THE CTLR HANDLING WHAT APPEARED TO BE AT LEAST 1 OTHER FREQ AND MIL TFC, AS SEVERAL TRANSMISSIONS WERE BLOCKED AND REPEATED. THE CAPT CHKED IN WITH CENTER WHOM SUBSEQUENTLY CLRED US TO FL230. THE CAPT SET IN 230 IN THE ALT ALERT AND I VERIFIED FL230. APCHING 16000 FT CENTER POINTED OUT TFC AT 11 O'CLOCK AND (AROUND 12-15 MI) AT 17000 FT. THE CAPT PICKED UP THE TFC VISUALLY VERY QUICKLY AND POINTED HIM OUT. I FIRST LOOKED AT THE TCASII, WHICH WAS IN THE RA MODE, AND THEN OBSERVED THE TFC VISUALLY. I REMEMBER THINKING THAT IT SEEMED A LITTLE ODD TO BE CLBING THROUGH HIS ALT WITH ONLY 4-5 MI HORIZ SEPARATION WITHOUT US ACKNOWLEDGING THAT WE HAD HIM VISUALLY FIRST. I DIDN'T FEEL WE WERE IN DANGER AT ANY TIME. THE CAPT SIGNALED TO ME VISUALLY TO LEVEL OFF, AS HE WAS THINKING THE SAME AS I. I MADE A SLOW LEVEL OFF WHICH TOOK A FEW HUNDRED FT DUE TO OUR CLB RATE. THE MAX ALT I RECALL WAS APPROX 16400 FT. A FEW SECONDS AFTER THE CAPT SIGNALED ME TO LEVEL OFF, ATC ASKED US TO VERIFY OUR ALT. THE CAPT RESPONDED THAT WE WERE DSNDING THROUGH 16400 DOWN TO 16000 FT. AT ABOUT THAT TIME WE RECEIVED A 'TFC, TFC' ALERT FROM TCASII, WHICH WAS IN THE RA MODE. AT NO TIME DID WE RECEIVE AN RA COMMAND! AFTER PASSING THE TFC ATC CLRED US TO CLB AGAIN. A FEW MINS LATER ATC ASKED US TO CALL THEM FROM DEN. THE 3 THINGS THAT STICK IN MY MIND AND THAT I AM POSITIVELY SURE ABOUT IS THAT: 1) ATC WAS HANDLING MORE THAN 1 FREQ. 2) THE CAPT ACKNOWLEDGED AND SET IN FL230 INTO THE ALT ALERT WINDOW. 3) I VERBALLY ACKNOWLEDGED IT.

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.