Narrative:

Location -- west of runway 25R las departure. Mccarran 2 departure requires heading 190 degrees at 3 DME of las. After airborne, during initial frequency change from tower to the departure control, both first officer and I thought to overhear 'maintain runway heading' with the call sign blocked. The departure frequency was very congested. We elected to stay on runway heading while I tried to contact the controller to verify the instruction. The frequency was very congested. By the time I was able to actually talk to the controller to verify the runway heading was for us, we exceeded the 3 DME limit. We were supposed to adhere to the SID, and turn at 3 DME. 'Maintain runway heading' instruction was not for us. I contacted the departure control supervisor later and discussed the situation, and was told that there were no traffic conflict or any other operational conflict were present at that time. Supplemental in from acn 595085: frequency/altitude: 125.9/5000 ft. Mccarren 2 SID. We were unable to establish radio contact with departure control due to frequency congestion, but thought I heard the controller say maintain runway heading. The WX was VFR clear skies, with unlimited visibility.

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Original NASA ASRS Text

Title: AN MD80 FLT CREW DEVIATED FROM THE HEADING TRACK REQUIREMENTS OF THE MCCARRAN TWO DEP PROC 3 NM W OF LAS, NV.

Narrative: LOCATION -- W OF RWY 25R LAS DEP. MCCARRAN 2 DEP REQUIRES HEADING 190 DEGS AT 3 DME OF LAS. AFTER AIRBORNE, DURING INITIAL FREQ CHANGE FROM TWR TO THE DEP CTL, BOTH FO AND I THOUGHT TO OVERHEAR 'MAINTAIN RWY HEADING' WITH THE CALL SIGN BLOCKED. THE DEP FREQ WAS VERY CONGESTED. WE ELECTED TO STAY ON RWY HEADING WHILE I TRIED TO CONTACT THE CTLR TO VERIFY THE INSTRUCTION. THE FREQ WAS VERY CONGESTED. BY THE TIME I WAS ABLE TO ACTUALLY TALK TO THE CTLR TO VERIFY THE RWY HEADING WAS FOR US, WE EXCEEDED THE 3 DME LIMIT. WE WERE SUPPOSED TO ADHERE TO THE SID, AND TURN AT 3 DME. 'MAINTAIN RWY HEADING' INSTRUCTION WAS NOT FOR US. I CONTACTED THE DEP CTL SUPVR LATER AND DISCUSSED THE SIT, AND WAS TOLD THAT THERE WERE NO TFC CONFLICT OR ANY OTHER OPERATIONAL CONFLICT WERE PRESENT AT THAT TIME. SUPPLEMENTAL IN FROM ACN 595085: FREQ/ALT: 125.9/5000 FT. MCCARREN 2 SID. WE WERE UNABLE TO ESTABLISH RADIO CONTACT WITH DEP CTL DUE TO FREQ CONGESTION, BUT THOUGHT I HEARD THE CTLR SAY MAINTAIN RWY HEADING. THE WX WAS VFR CLR SKIES, WITH UNLIMITED VISIBILITY.

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.