Narrative:

I operated as pilot flying (captain) on flight from ZZZ to ZZZ1. During the takeoff; my airspeed read 80 KIAS. My first officer said nothing. I responded '90 KIAS.' I was unclear what was going on. He said something like '80'. At this point we were above 100 KIAS. Weather was VMC. Rather than execute high speed reject; I continued takeoff. Going airborne; after getting gear up; I noticed I lost my flight director and auto throttles disengaged. I flew raw data. Rather than make the turn on the SID; I asked for straight ahead. Noticing several TCAS targets and unsure of the aircrafts' status; we elected to [advise ATC]. We retracted the flaps; left slats out; and I called for [personnel] to come forward to work with first officer as we climbed to 4;000 ft. The first officer and [personnel] ran (lvl 2) 'sel elev feel man' and (lvl 2) 'sel flap lim ovrd' checklists. Both directed us to 'non alert' 'airspeed unreliable' checklist. This checklist isolated the (suspected) faulty component as CADC2. First officer selected data off my side... Normal indications. Since we had [advised ATC] and at the time of takeoff there was convective activity on the first third of our route; I elected to return to ZZZ. First officer and [personnel] worked landing data; got ATIS; used 'divert' function of ACARS. We flew uneventful arrival and ILS to [runway] xxl. Hats off to TRACON for excellent handling and reference airspeed calls. Also to ZZZ arff (airport rescue and firefighting) for excellent response.

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Original NASA ASRS Text

Title: MD-11 Captain reported that CADC2 failed during takeoff resulting in a return to departure airport.

Narrative: I operated as Pilot Flying (Captain) on flight from ZZZ to ZZZ1. During the takeoff; my airspeed read 80 KIAS. My First Officer said nothing. I responded '90 KIAS.' I was unclear what was going on. He said something like '80'. At this point we were above 100 KIAS. Weather was VMC. Rather than execute high speed reject; I continued takeoff. Going airborne; after getting gear up; I noticed I lost my flight director and auto throttles disengaged. I flew raw data. Rather than make the turn on the SID; I asked for straight ahead. Noticing several TCAS targets and unsure of the aircrafts' status; we elected to [advise ATC]. We retracted the flaps; left slats out; and I called for [personnel] to come forward to work with First Officer as we climbed to 4;000 ft. The First Officer and [personnel] ran (lvl 2) 'SEL ELEV FEEL MAN' and (lvl 2) 'SEL FLAP LIM OVRD' checklists. Both directed us to 'Non Alert' 'Airspeed Unreliable' checklist. This checklist isolated the (suspected) faulty component as CADC2. First Officer selected data off my side... normal indications. Since we had [advised ATC] and at the time of takeoff there was convective activity on the first third of our route; I elected to return to ZZZ. First Officer and [personnel] worked landing data; got ATIS; used 'divert' function of ACARS. We flew uneventful arrival and ILS to [Runway] XXL. Hats off to TRACON for excellent handling and reference airspeed calls. Also to ZZZ ARFF (Airport Rescue and Firefighting) for excellent response.

Data retrieved from NASA's ASRS site 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.