Possible air carrier medium large transport takeoff without clearance.

Attributes
ACN	145625
Time
Date	199005
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : mdw
State Reference	IL
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mdw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	climbout : takeoff ground : holding
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 12000 flight time type : 8000
ASRS Report	145625
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Pilot Deviation

Narrative:

We were cleared for immediate takeoff with traffic 2 mi east and instructions to turn right to 230 degrees. We continued the pretkof checklist to conclusion as we came around the corner and advanced power to takeoff thrust. As soon as we finished the pretkof checklist my first officer and I both heard 'turn right.' my first officer repeated 'turn right,' but misstated the assigned heading as 330 degrees. After takeoff tower queried us as to whether we heard his instructions to clear the runway. We hadn't, probably due to our concentration on the pretkof checklist. I believe tower was concerned about the traffic on final conflicting with us. We really didn't hear him cancel our takeoff clearance (if that is what he did). Since we already had takeoff thrust set we wouldn't have been able to clear the runway until the first or even second exit which would have made the other aircraft go around. We may have screwed up, but any course of action other than continuing the takeoff would have had more severe ramifications.

Original NASA ASRS Text

Title: POSSIBLE ACR MLG TKOF WITHOUT CLRNC.

Narrative: WE WERE CLRED FOR IMMEDIATE TKOF WITH TFC 2 MI E AND INSTRUCTIONS TO TURN RIGHT TO 230 DEGS. WE CONTINUED THE PRETKOF CHKLIST TO CONCLUSION AS WE CAME AROUND THE CORNER AND ADVANCED PWR TO TKOF THRUST. AS SOON AS WE FINISHED THE PRETKOF CHKLIST MY F/O AND I BOTH HEARD 'TURN RIGHT.' MY F/O REPEATED 'TURN RIGHT,' BUT MISSTATED THE ASSIGNED HDG AS 330 DEGS. AFTER TKOF TWR QUERIED US AS TO WHETHER WE HEARD HIS INSTRUCTIONS TO CLR THE RWY. WE HADN'T, PROBABLY DUE TO OUR CONCENTRATION ON THE PRETKOF CHKLIST. I BELIEVE TWR WAS CONCERNED ABOUT THE TFC ON FINAL CONFLICTING WITH US. WE REALLY DIDN'T HEAR HIM CANCEL OUR TKOF CLRNC (IF THAT IS WHAT HE DID). SINCE WE ALREADY HAD TKOF THRUST SET WE WOULDN'T HAVE BEEN ABLE TO CLR THE RWY UNTIL THE FIRST OR EVEN SECOND EXIT WHICH WOULD HAVE MADE THE OTHER ACFT GO AROUND. WE MAY HAVE SCREWED UP, BUT ANY COURSE OF ACTION OTHER THAN CONTINUING THE TKOF WOULD HAVE HAD MORE SEVERE RAMIFICATIONS.

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.