A MD80's autothrottle system failed during takeoff because of a number two air data computer fault. ...

Narrative:

Takeoff runway 18L. Captain flying. First officer calls out '80 KTS.' auto throttles disconnected shortly after and EPR chevrons began to roll towards 1.0. I advised captain. Captain rotated about 10 KTS early (on my airspeed indicator). When I saw V1 I called it out with a tone that reflected that we were just now reaching V1. As I called out 'rotate;' the aircraft was already lifting off. Captain stated the airspeeds differed. Cross checking showed that captain and 'standby' indicators agreed. V bars biased out of view. I reported to tower we were 'unable RNAV.' tower switched us to departure and told us to tell them. Departure gave us vectors for the remaining of the SID. We ran checklists and completed the flight with CADC both on 1. Once 'both on 1;' we were able to engage autopilot and continue with RNAV navigation. I asked for and received an intermediate level off at FL220 to work the checklists. We received multiple CAWS 'overspeed' warnings (with none of the 3 airspeed indicators near the 'barber pole') and after running appropriate checklists; continued uneventful to our filed destination.

Original NASA ASRS Text

Title: A MD80's autothrottle system failed during takeoff because of a number two air data computer fault. The First Officer's airspeed was in error and the Captain rotated 10 KTS early according to the First Officer's reading.

Narrative: Takeoff Runway 18L. Captain flying. First Officer calls out '80 KTS.' Auto throttles disconnected shortly after and EPR Chevrons began to roll towards 1.0. I advised Captain. Captain rotated about 10 KTS early (on my airspeed indicator). When I saw V1 I called it out with a tone that reflected that we were just now reaching V1. As I called out 'rotate;' the aircraft was already lifting off. Captain stated the airspeeds differed. Cross checking showed that Captain and 'Standby' indicators agreed. V bars biased out of view. I reported to Tower we were 'unable RNAV.' Tower switched us to Departure and told us to tell them. Departure gave us vectors for the remaining of the SID. We ran checklists and completed the flight with CADC both on 1. Once 'both on 1;' we were able to engage autopilot and continue with RNAV navigation. I asked for and received an intermediate level off at FL220 to work the checklists. We received multiple CAWS 'overspeed' warnings (with none of the 3 airspeed indicators near the 'barber pole') and after running appropriate checklists; continued uneventful to our filed destination.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	877605
Time
Date	201003
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Dusk
Aircraft 1
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Initial Climb
Flight Plan	IFR
Component
Aircraft Component	Autothrottle/Speed Control
Person 1
Function	First Officer Pilot Not Flying
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy

A MD80's autothrottle system failed during takeoff because of a number two air data computer fault. The first officer's airspeed was in error and the captain rotated 10 KTS early according to the first officer's reading.