Flight crew of LJ45 mistakenly start takeoff roll at cxy when only cleared into position and hold.

Attributes
ACN	590665
Time
Date	200308
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cxy.airport
State Reference	PA
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Learjet 45
Operating Under FAR Part	Part 91
Flight Phase	ground : position and hold ground : takeoff roll
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 100 flight time total : 15800 flight time type : 1350
ASRS Report	590665
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 6500 flight time type : 1000
ASRS Report	590273
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance controller : issued alert flight crew : rejected takeoff
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were about to depart cxy when we received a reroute from tower. While we were loading the new route in our FMS, tower advised us to, 'let me know when you are ready,' or words to that effect. He then told us to taxi into position and hold, but thinking that we would be cleared for takeoff as soon as we were 'ready,' I began my takeoff roll. Tower immediately advised us that we had not been released. We aborted our takeoff immediately and taxied back. We then received our takeoff clearance and proceeded with our flight. I believe that what really caused this problem was my attention to the reroute, and to the fact that when the tower told us to advise him when we were ready, I had the assumption in my mind that we would be cleared for takeoff when we were ready. Supplemental information from acn 590273: the crew was preoccupied with setting in a new route and circumnaving the WX in the area. The tower used relaxed and ambiguous language. Both pilots must agree on any clearance and not accept non standard phrases.

Original NASA ASRS Text

Title: FLT CREW OF LJ45 MISTAKENLY START TKOF ROLL AT CXY WHEN ONLY CLRED INTO POS AND HOLD.

Narrative: WE WERE ABOUT TO DEPART CXY WHEN WE RECEIVED A REROUTE FROM TWR. WHILE WE WERE LOADING THE NEW RTE IN OUR FMS, TWR ADVISED US TO, 'LET ME KNOW WHEN YOU ARE READY,' OR WORDS TO THAT EFFECT. HE THEN TOLD US TO TAXI INTO POS AND HOLD, BUT THINKING THAT WE WOULD BE CLRED FOR TKOF AS SOON AS WE WERE 'READY,' I BEGAN MY TKOF ROLL. TWR IMMEDIATELY ADVISED US THAT WE HAD NOT BEEN RELEASED. WE ABORTED OUR TKOF IMMEDIATELY AND TAXIED BACK. WE THEN RECEIVED OUR TKOF CLRNC AND PROCEEDED WITH OUR FLT. I BELIEVE THAT WHAT REALLY CAUSED THIS PROB WAS MY ATTN TO THE REROUTE, AND TO THE FACT THAT WHEN THE TWR TOLD US TO ADVISE HIM WHEN WE WERE READY, I HAD THE ASSUMPTION IN MY MIND THAT WE WOULD BE CLRED FOR TKOF WHEN WE WERE READY. SUPPLEMENTAL INFO FROM ACN 590273: THE CREW WAS PREOCCUPIED WITH SETTING IN A NEW RTE AND CIRCUMNAVING THE WX IN THE AREA. THE TWR USED RELAXED AND AMBIGUOUS LANGUAGE. BOTH PLTS MUST AGREE ON ANY CLRNC AND NOT ACCEPT NON STANDARD PHRASES.

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.