As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ATC REPORTED INTERMITTENT MODE C. ALTITUDE REPORTING FAILURES IN ROUTE. ATC TRANSPONDER/AUTOMATIC ALTITUDE REPORT SYS AND A/C VACATED RVSM AIRSPACE. USE FLT AWARE TO VERIFY DATA GAPS FOR THIS FLIGHT. C/A: R/R ATC TRANSPONDER 1 +2 IAW A319 AMM 34-52 BITE TEST PASSED FUNCTION TEST OF ATC/MODE S IAW A319 AMM 34-52 PASSED THIS CLEAR MEL PLACARDS REMOVED NO M PROCEDURES TO RESTORE. (LP: 8904918, AIRCRAFT WAS GROUNDED)