Narrative:

During initial climb noted altitude miscompare altitude alert on captains pfd instrument. At this time I cross checked my baro setting and altitude to the first officer and seemed normal. Passing thru 3000 ft I noted the first officer altitude miscompare also. I asked the first officer to put autopilot on due to previous maintenance write up for CADC2 failure and suspected airspeed unreliable. We were now well above the overcast cloud layer in VMC. Ran airspeed unreliable checklist. Determined that CADC2 was bad and got numerous altitude and airspeed edification checks from ATC. Stopped climb at FL330 and notified ATC that our altitude and airspeed were unreliable and inaccurate due to equipment malfunction. Got block altitude clearance of Fl320-FL340 and leveled off using vertical speed 0 at FL330 and [advised ATC] due to safety concerns and degraded capability. We also got wind shear det fail and IAS miscompare alerts. ATC confirmed our altitude as FL331 which agreed with the ca instruments. We noted/checked and verified our pitch and power settings for each phase and configuration of flight and all seemed ok after selecting CADC1 as good. We also got our altitude selector window back and prof. After contacting goc we determined that best option was to continue to destination as weather was VMC and we could descend VMC to landing per the checklist and they had parts. We received priority handling from ATC and did a long slow straight in ILS; captain did approach and landing; to successful landing. First officer did a great job with the checklists and backing up configuration speeds and verification checks with ATC. Event caused by bad CADC2. We ran the airspeed unreliable checklist and completed flight using good CADC1.

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Original NASA ASRS Text

Title: MD11 Captain reported a Central Air Data Computer 2 (CADC2) failure on climbout that resulted in unreliable airspeed and altitude information.

Narrative: During initial climb noted altitude miscompare ALT alert on Captains PFD instrument. At this time I cross checked my baro setting and altitude to the FO and seemed normal. Passing thru 3000 FT I noted the FO altitude miscompare also. I asked the FO to put autopilot on due to previous maintenance write up for CADC2 failure and suspected Airspeed Unreliable. We were now well above the overcast cloud layer in VMC. Ran Airspeed Unreliable checklist. Determined that CADC2 was bad and got numerous altitude and Airspeed edification checks from ATC. Stopped climb at FL330 and notified ATC that our altitude and Airspeed were Unreliable and inaccurate due to equipment malfunction. Got block altitude clearance of Fl320-FL340 and leveled off using vertical speed 0 at FL330 and [advised ATC] due to safety concerns and degraded capability. We also got wind shear det fail and IAS miscompare alerts. ATC confirmed our altitude as FL331 which agreed with the CA instruments. We noted/checked and verified our pitch and power settings for each phase and configuration of flight and all seemed ok after selecting CADC1 as good. We also got our altitude selector window back and PROF. After contacting GOC we determined that best option was to continue to destination as weather was VMC and we could descend VMC to landing per the checklist and they had parts. We received priority handling from ATC and did a long slow straight in ILS; Captain did approach and landing; to successful landing. FO did a great job with the checklists and backing up configuration speeds and verification checks with ATC. Event caused by bad CADC2. We ran the Airspeed Unreliable checklist and completed flight using good CADC1.

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.