A B737-300 was dispatched with the captain's pitot input to the air data computer disconnected.

Attributes
ACN	394560
Time
Date	199802
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz
State Reference	US
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	other
Flight Plan	None
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	394560
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence : published procedure other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

At approximately XA30 feb/xa/98, I was assigned aircraft YYY (a commercial passenger B737-300 turbojet) turn-over from prior shift maintenance. The pilot write-up was they were getting an 'att' flag in the captain's ADI (altitude director indicator) during climb out. The prior shift a&P mechanic replaced the left IRU (inertial reference unit) but did not fix the problem. On my shift I troubleshot the problem to the left daa unit (digital analog adapter), but our station did not have one in stock. I swapped the right daa unit with the left daa to verify that the left daa was in fact faulty. It was. While swapping the left daa unit with the right daa unit I accidentally must have disconnected the flex line to the air data computer. Before I closed the electrical bay door, I looked around the areas that I was working and everything appeared to be in place. I was done with my shift at XI00. At approximately XJ45 aircraft YYY was on takeoff roll. The captain noticed he had no airspeed indication and aborted takeoff and returned to gate. The mechanics on the day shift fixed the problem and the aircraft departed with no further incident.

Original NASA ASRS Text

Title: A B737-300 WAS DISPATCHED WITH THE CAPT'S PITOT INPUT TO THE AIR DATA COMPUTER DISCONNECTED.

Narrative: AT APPROX XA30 FEB/XA/98, I WAS ASSIGNED ACFT YYY (A COMMERCIAL PAX B737-300 TURBOJET) TURN-OVER FROM PRIOR SHIFT MAINT. THE PLT WRITE-UP WAS THEY WERE GETTING AN 'ATT' FLAG IN THE CAPT'S ADI (ALT DIRECTOR INDICATOR) DURING CLBOUT. THE PRIOR SHIFT A&P MECH REPLACED THE L IRU (INERTIAL REF UNIT) BUT DID NOT FIX THE PROB. ON MY SHIFT I TROUBLESHOT THE PROB TO THE L DAA UNIT (DIGITAL ANALOG ADAPTER), BUT OUR STATION DID NOT HAVE ONE IN STOCK. I SWAPPED THE R DAA UNIT WITH THE L DAA TO VERIFY THAT THE L DAA WAS IN FACT FAULTY. IT WAS. WHILE SWAPPING THE L DAA UNIT WITH THE R DAA UNIT I ACCIDENTALLY MUST HAVE DISCONNECTED THE FLEX LINE TO THE AIR DATA COMPUTER. BEFORE I CLOSED THE ELECTRICAL BAY DOOR, I LOOKED AROUND THE AREAS THAT I WAS WORKING AND EVERYTHING APPEARED TO BE IN PLACE. I WAS DONE WITH MY SHIFT AT XI00. AT APPROX XJ45 ACFT YYY WAS ON TKOF ROLL. THE CAPT NOTICED HE HAD NO AIRSPD INDICATION AND ABORTED TKOF AND RETURNED TO GATE. THE MECHS ON THE DAY SHIFT FIXED THE PROB AND THE ACFT DEPARTED WITH NO FURTHER INCIDENT.

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.