Narrative:

Prior departure from dfw runway 17L aircraft radar indicated a larger cell approximately 5 mi south of the airport (cell was approximately 4 mi deep and 15 mi long) tower asked if we would accept a straight out departure. We declined, requesting a left turn. Clearance was given for takeoff with an immediate turn to a heading of 090 degrees. After takeoff a turn 090 degrees was made. It was immediately apparently that this heading would not allow us to remain clear of the thunderstorm cell. The captain made a turn to an approximately heading of 070 degrees and I informed departure that we were turning further left to a heading of 060 degrees. Due to the vol of radio calls being made, no reply was received. The controller eventually called to request our heading and I informed him 060 degrees for WX. He advised us that west were not authority/authorized to take up that heading, by which time it had become possible to make a turn back to a heading of 090 degrees and the controller gave us clearance to join the 078 degree right from dfw. The remainder of the flight continued west/O incident. This incident occurred because air traffic control continued to release aircraft into the face of a known thunderstorm west/O a clearance to deviate as required to remain clear of the thunderstorm cell.

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Original NASA ASRS Text

Title: UNABLE TO MAINTAIN 090 DEGS HEADING ACCOUNT TSTM. FREQ CONGESTION.

Narrative: PRIOR DEP FROM DFW RWY 17L ACFT RADAR INDICATED A LARGER CELL APPROX 5 MI S OF THE ARPT (CELL WAS APPROX 4 MI DEEP AND 15 MI LONG) TWR ASKED IF WE WOULD ACCEPT A STRAIGHT OUT DEP. WE DECLINED, REQUESTING A LEFT TURN. CLRNC WAS GIVEN FOR TKOF WITH AN IMMEDIATE TURN TO A HDG OF 090 DEGS. AFTER TKOF A TURN 090 DEGS WAS MADE. IT WAS IMMEDIATELY APPARENTLY THAT THIS HDG WOULD NOT ALLOW US TO REMAIN CLR OF THE TSTM CELL. THE CAPT MADE A TURN TO AN APPROX HDG OF 070 DEGS AND I INFORMED DEP THAT WE WERE TURNING FURTHER LEFT TO A HDG OF 060 DEGS. DUE TO THE VOL OF RADIO CALLS BEING MADE, NO REPLY WAS RECEIVED. THE CTLR EVENTUALLY CALLED TO REQUEST OUR HDG AND I INFORMED HIM 060 DEGS FOR WX. HE ADVISED US THAT W WERE NOT AUTH TO TAKE UP THAT HDG, BY WHICH TIME IT HAD BECOME POSSIBLE TO MAKE A TURN BACK TO A HDG OF 090 DEGS AND THE CTLR GAVE US CLRNC TO JOIN THE 078 DEG R FROM DFW. THE REMAINDER OF THE FLT CONTINUED W/O INCIDENT. THIS INCIDENT OCCURRED BECAUSE AIR TFC CTL CONTINUED TO RELEASE ACFT INTO THE FACE OF A KNOWN TSTM W/O A CLRNC TO DEVIATE AS REQUIRED TO REMAIN CLR OF THE TSTM CELL.

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.