Narrative:

Air carrier X on climb out radar showed rapidly developing cells accompanied by turbulence, rain and lightning. Obviously the frequency started getting saturated with requests for deviations around WX. Many xmissions were blocked or garbled as everyone tried to get a deviation around WX. I was handling the radios and at the same time watching the flight and engine instruments, looking at the radar and evaluating the situation so as to suggest a possible course of action around the cells. The comfort and safety of the passenger was also occupying my mind. On the frequency I had heard another air carrier request for 16000'. Thought nothing of it as it did not apply to us. This transmission was I believe to be garbled due to the many aircraft on the frequency. When the PF stopped the climb (we were past 16000') and mentioned 16000' MSL to me, my first concern was that I had missed a call from ATC. In the time that it took for this to happen, ATC came back and requested that we continue the climb to our assigned altitude. Of course we complied immediately. This event reassured me that I had not missed the call and it was just a case of saturation of the frequency given, the conditions and number of aircraft operating. In my view the situation could have been avoided by radio discipline in the sense that many times communications are blocked right in the middle of a transmission. Another suggestion would be for the PF to confirm with the other pilot as to altitude that a flight has been cleared to when that altitude differs from what was set in the altitude alert system. Supplemental information from acn 144890: I was in command of and flying air carrier X ord-iah. Climb out from ord toward rbs required deviation around numerous developing thunderstorms which produced a widespread area of continuous moderate turbulence in clouds. My ATC clearance was to deviate as necessary, fly direct rbs when able and climb to FL230. At approximately 16400' ATC requested that I expedite through 17000'. At approximately 16600' ATC urgently cleared to 16000'. Shortly thereafter, before I reached 16000' ATC urgently cleared to 17000' and immediately turn left (no specific heading given). I complied and was subsequently reclred to FL230 and stl. It sounded as if more than 1 controller gave clrncs and seemed that whatever traffic conflict they had caught them by surprise. Perhaps my climb rate toward FL230 was not as fast as they expected because of the WX situation. I do not know why I was cleared to descend to 16000' unless it was an error or the controller misspoke because the clearance back to 17000' came so soon after.

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Original NASA ASRS Text

Title: ACR X FLT CREW FAILED TO COMPLY WITH ATC CLRNC. PLT DEVIATION.

Narrative: ACR X ON CLBOUT RADAR SHOWED RAPIDLY DEVELOPING CELLS ACCOMPANIED BY TURB, RAIN AND LIGHTNING. OBVIOUSLY THE FREQ STARTED GETTING SATURATED WITH REQUESTS FOR DEVIATIONS AROUND WX. MANY XMISSIONS WERE BLOCKED OR GARBLED AS EVERYONE TRIED TO GET A DEVIATION AROUND WX. I WAS HANDLING THE RADIOS AND AT THE SAME TIME WATCHING THE FLT AND ENG INSTS, LOOKING AT THE RADAR AND EVALUATING THE SIT SO AS TO SUGGEST A POSSIBLE COURSE OF ACTION AROUND THE CELLS. THE COMFORT AND SAFETY OF THE PAX WAS ALSO OCCUPYING MY MIND. ON THE FREQ I HAD HEARD ANOTHER ACR REQUEST FOR 16000'. THOUGHT NOTHING OF IT AS IT DID NOT APPLY TO US. THIS XMISSION WAS I BELIEVE TO BE GARBLED DUE TO THE MANY ACFT ON THE FREQ. WHEN THE PF STOPPED THE CLB (WE WERE PAST 16000') AND MENTIONED 16000' MSL TO ME, MY FIRST CONCERN WAS THAT I HAD MISSED A CALL FROM ATC. IN THE TIME THAT IT TOOK FOR THIS TO HAPPEN, ATC CAME BACK AND REQUESTED THAT WE CONTINUE THE CLB TO OUR ASSIGNED ALT. OF COURSE WE COMPLIED IMMEDIATELY. THIS EVENT REASSURED ME THAT I HAD NOT MISSED THE CALL AND IT WAS JUST A CASE OF SATURATION OF THE FREQ GIVEN, THE CONDITIONS AND NUMBER OF ACFT OPERATING. IN MY VIEW THE SIT COULD HAVE BEEN AVOIDED BY RADIO DISCIPLINE IN THE SENSE THAT MANY TIMES COMS ARE BLOCKED RIGHT IN THE MIDDLE OF A XMISSION. ANOTHER SUGGESTION WOULD BE FOR THE PF TO CONFIRM WITH THE OTHER PLT AS TO ALT THAT A FLT HAS BEEN CLRED TO WHEN THAT ALT DIFFERS FROM WHAT WAS SET IN THE ALT ALERT SYS. SUPPLEMENTAL INFO FROM ACN 144890: I WAS IN COMMAND OF AND FLYING ACR X ORD-IAH. CLBOUT FROM ORD TOWARD RBS REQUIRED DEVIATION AROUND NUMEROUS DEVELOPING TSTMS WHICH PRODUCED A WIDESPREAD AREA OF CONTINUOUS MODERATE TURB IN CLOUDS. MY ATC CLRNC WAS TO DEVIATE AS NECESSARY, FLY DIRECT RBS WHEN ABLE AND CLB TO FL230. AT APPROX 16400' ATC REQUESTED THAT I EXPEDITE THROUGH 17000'. AT APPROX 16600' ATC URGENTLY CLRED TO 16000'. SHORTLY THEREAFTER, BEFORE I REACHED 16000' ATC URGENTLY CLRED TO 17000' AND IMMEDIATELY TURN LEFT (NO SPECIFIC HDG GIVEN). I COMPLIED AND WAS SUBSEQUENTLY RECLRED TO FL230 AND STL. IT SOUNDED AS IF MORE THAN 1 CTLR GAVE CLRNCS AND SEEMED THAT WHATEVER TFC CONFLICT THEY HAD CAUGHT THEM BY SURPRISE. PERHAPS MY CLB RATE TOWARD FL230 WAS NOT AS FAST AS THEY EXPECTED BECAUSE OF THE WX SIT. I DO NOT KNOW WHY I WAS CLRED TO DSND TO 16000' UNLESS IT WAS AN ERROR OR THE CTLR MISSPOKE BECAUSE THE CLRNC BACK TO 17000' CAME SO SOON AFTER.

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.