As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(SUPP-CLOSED) FLIGHT NUMBER 279. DURING CLIMB AND CRUISE CAPTAINS VSI FLUCTUATES +- 500 FEET TO 1000 FEET. SWITCHED TO ALTN IRS AND FLUCTUATIONS STOPPED. MAINTENANCE REMOVED AND REPLACED VSI PER MM 34-22-06-4. OPERATIONAL CHECKS NORMAL.