Narrative:

We were cleared into position on runway 29 in ewr and completed the before takeoff checklist to the line. We were expecting to fly the ewr runway 7 SID (265 degrees, 5000 ft). As another aircraft was landing on runway 22L, ATC said 'fly runway heading, maintain 2000 ft,' and we commenced the takeoff. A few hundred feet into the air, ATC said that we had not been cleared for takeoff and to look for a helicopter ahead. We saw it and did not need to change our flight path and there was no TA or RA. I told ATC what I had heard as the takeoff clearance, but he repeated that we weren't cleared. Both the first officer and I were stunned by this. Everything was in place for our departure. The crossing traffic landed, the runway was clear and ATC gave us instructions consistent with a takeoff clearance. Normally, if ATC had alternate instructions, but not a clearance, they are very clear about continuing to hold. Our instructions were typical of a change in departure plans that are followed by a takeoff clearance. Upon arrival at destination, we briefed our chief pilot. I was asked to call ewr tower and the supervisor asked me for my contact information and said there was going to be an investigation. Shortly thereafter, I received a call, but let it go to voicemail and it was the tower calling me. Before I called back, I advised my chief pilot that I had originally planned to take a nap during my 2 hour break, but since I was tied up with this event, I would need to be relieved of my last turn due to fatigue. I had a reduced rest 2 nights ago (5.5 hours of sleep) and an XA30 am wakeup call this morning (5-6 hours of sleep). I figured I had enough for 1 day and that it wasn't safe to fly the last turn given the lack of sleep and the stress of a possible certificate action. While I believe the overwhelming reason we commenced the takeoff was due to the timing and nature of ATC's transmission, the lack of sleep certainly diminished my alertness, but not to a degree that I felt at risk as the WX was clear. I take extra diligence and care when lacking a full night's sleep. I returned the call to the ewr tower about 1 hour after receiving the voicemail. I was told that after review of the tape, the ambiguity was apparent and that no further action would be taken. I was advised to be more alert to the specific 'cleared for takeoff' clearance and the controller that worked my flight was advised to reiterate the 'position and hold' instruction next time. When a crew takes the runway, there is the anticipation of an imminent departure. The issuance of alternate takeoff instructions without a takeoff clearance is to a degree abnormal and unexpected and I believe controllers should be extra cautious by reiterating the current 'position and hold' clearance. This event certainly got my attention, and I'll be even more diligent in the future. Also, ATC at ewr was very professional during the event and on the phone as well.

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Original NASA ASRS Text

Title: EMBRAER 145 JET FLC TOOK OFF WITHOUT CLRNC DUE TO A MISUNDERSTANDING OF TWR CLRNC WHILE IN POS AND HOLDING.

Narrative: WE WERE CLRED INTO POS ON RWY 29 IN EWR AND COMPLETED THE BEFORE TKOF CHKLIST TO THE LINE. WE WERE EXPECTING TO FLY THE EWR RWY 7 SID (265 DEGS, 5000 FT). AS ANOTHER ACFT WAS LNDG ON RWY 22L, ATC SAID 'FLY RWY HEADING, MAINTAIN 2000 FT,' AND WE COMMENCED THE TKOF. A FEW HUNDRED FEET INTO THE AIR, ATC SAID THAT WE HAD NOT BEEN CLRED FOR TKOF AND TO LOOK FOR A HELI AHEAD. WE SAW IT AND DID NOT NEED TO CHANGE OUR FLT PATH AND THERE WAS NO TA OR RA. I TOLD ATC WHAT I HAD HEARD AS THE TKOF CLRNC, BUT HE REPEATED THAT WE WEREN'T CLRED. BOTH THE FO AND I WERE STUNNED BY THIS. EVERYTHING WAS IN PLACE FOR OUR DEP. THE XING TFC LANDED, THE RWY WAS CLR AND ATC GAVE US INSTRUCTIONS CONSISTENT WITH A TKOF CLRNC. NORMALLY, IF ATC HAD ALTERNATE INSTRUCTIONS, BUT NOT A CLRNC, THEY ARE VERY CLR ABOUT CONTINUING TO HOLD. OUR INSTRUCTIONS WERE TYPICAL OF A CHANGE IN DEP PLANS THAT ARE FOLLOWED BY A TKOF CLRNC. UPON ARR AT DEST, WE BRIEFED OUR CHIEF PLT. I WAS ASKED TO CALL EWR TWR AND THE SUPVR ASKED ME FOR MY CONTACT INFO AND SAID THERE WAS GOING TO BE AN INVESTIGATION. SHORTLY THEREAFTER, I RECEIVED A CALL, BUT LET IT GO TO VOICEMAIL AND IT WAS THE TWR CALLING ME. BEFORE I CALLED BACK, I ADVISED MY CHIEF PLT THAT I HAD ORIGINALLY PLANNED TO TAKE A NAP DURING MY 2 HR BREAK, BUT SINCE I WAS TIED UP WITH THIS EVENT, I WOULD NEED TO BE RELIEVED OF MY LAST TURN DUE TO FATIGUE. I HAD A REDUCED REST 2 NIGHTS AGO (5.5 HRS OF SLEEP) AND AN XA30 AM WAKEUP CALL THIS MORNING (5-6 HRS OF SLEEP). I FIGURED I HAD ENOUGH FOR 1 DAY AND THAT IT WASN'T SAFE TO FLY THE LAST TURN GIVEN THE LACK OF SLEEP AND THE STRESS OF A POSSIBLE CERTIFICATE ACTION. WHILE I BELIEVE THE OVERWHELMING REASON WE COMMENCED THE TKOF WAS DUE TO THE TIMING AND NATURE OF ATC'S XMISSION, THE LACK OF SLEEP CERTAINLY DIMINISHED MY ALERTNESS, BUT NOT TO A DEGREE THAT I FELT AT RISK AS THE WX WAS CLR. I TAKE EXTRA DILIGENCE AND CARE WHEN LACKING A FULL NIGHT'S SLEEP. I RETURNED THE CALL TO THE EWR TWR ABOUT 1 HR AFTER RECEIVING THE VOICEMAIL. I WAS TOLD THAT AFTER REVIEW OF THE TAPE, THE AMBIGUITY WAS APPARENT AND THAT NO FURTHER ACTION WOULD BE TAKEN. I WAS ADVISED TO BE MORE ALERT TO THE SPECIFIC 'CLRED FOR TKOF' CLRNC AND THE CTLR THAT WORKED MY FLT WAS ADVISED TO REITERATE THE 'POS AND HOLD' INSTRUCTION NEXT TIME. WHEN A CREW TAKES THE RWY, THERE IS THE ANTICIPATION OF AN IMMINENT DEP. THE ISSUANCE OF ALTERNATE TKOF INSTRUCTIONS WITHOUT A TKOF CLRNC IS TO A DEGREE ABNORMAL AND UNEXPECTED AND I BELIEVE CTLRS SHOULD BE EXTRA CAUTIOUS BY REITERATING THE CURRENT 'POS AND HOLD' CLRNC. THIS EVENT CERTAINLY GOT MY ATTN, AND I'LL BE EVEN MORE DILIGENT IN THE FUTURE. ALSO, ATC AT EWR WAS VERY PROFESSIONAL DURING THE EVENT AND ON THE PHONE AS WELL.

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.