B737 crew took off without clearance.

Attributes
ACN	421435
Time
Date	199811
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sea
State Reference	WA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 4000 flight time type : 2000
ASRS Report	421435
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : clearance other anomaly other
Independent Detector	other other : unspecified
Resolutory Action	none taken : insufficient time
Consequence	Other
Supplementary
Air Traffic Incident	Pilot Deviation

Narrative:

We were #1 for takeoff on taxiway B runway 16L at sea. We were cleared for takeoff from taxiway B. The captain asked me to ask for an early left turn after takeoff to avoid WX on the departure path of runway 16L. I responded 'air carrier abcd cleared for takeoff runway 16L and would like an early turn to the left to avoid WX.' the captain asked for the final items on the before takeoff checklist. Then the captain began the takeoff roll. At about 60-80 KTS, the observer (jump seater) who was from the equipment industry that had authority/authorized from flight management, said we were not cleared for takeoff. At that point I asked 'air carrier abcd cleared for takeoff' and there was no response. The captain elected to continue the takeoff roll. The captain asked me if I heard 'clear for takeoff' and we both agreed that we had a takeoff clearance. After takeoff, the tower came back and said we were not cleared for takeoff. We discussed this with the observer and he heard 'cleared for takeoff' and then shortly after 'taxi in position and hold.' we feel this would have been avoided if the tower would have stated 'air carrier abcd cancel takeoff clearance.' when you hear position and hold after being cleared for takeoff, one assumes it is for the aircraft behind you.

Original NASA ASRS Text

Title: B737 CREW TOOK OFF WITHOUT CLRNC.

Narrative: WE WERE #1 FOR TKOF ON TXWY B RWY 16L AT SEA. WE WERE CLRED FOR TKOF FROM TXWY B. THE CAPT ASKED ME TO ASK FOR AN EARLY L TURN AFTER TKOF TO AVOID WX ON THE DEP PATH OF RWY 16L. I RESPONDED 'ACR ABCD CLRED FOR TKOF RWY 16L AND WOULD LIKE AN EARLY TURN TO THE L TO AVOID WX.' THE CAPT ASKED FOR THE FINAL ITEMS ON THE BEFORE TKOF CHKLIST. THEN THE CAPT BEGAN THE TKOF ROLL. AT ABOUT 60-80 KTS, THE OBSERVER (JUMP SEATER) WHO WAS FROM THE EQUIP INDUSTRY THAT HAD AUTH FROM FLT MGMNT, SAID WE WERE NOT CLRED FOR TKOF. AT THAT POINT I ASKED 'ACR ABCD CLRED FOR TKOF' AND THERE WAS NO RESPONSE. THE CAPT ELECTED TO CONTINUE THE TKOF ROLL. THE CAPT ASKED ME IF I HEARD 'CLR FOR TKOF' AND WE BOTH AGREED THAT WE HAD A TKOF CLRNC. AFTER TKOF, THE TWR CAME BACK AND SAID WE WERE NOT CLRED FOR TKOF. WE DISCUSSED THIS WITH THE OBSERVER AND HE HEARD 'CLRED FOR TKOF' AND THEN SHORTLY AFTER 'TAXI IN POS AND HOLD.' WE FEEL THIS WOULD HAVE BEEN AVOIDED IF THE TWR WOULD HAVE STATED 'ACR ABCD CANCEL TKOF CLRNC.' WHEN YOU HEAR POS AND HOLD AFTER BEING CLRED FOR TKOF, ONE ASSUMES IT IS FOR THE ACFT BEHIND YOU.

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.