Unions at Flightcare had threatened to take strike action earlier this summer, but withdrew the threat after management promises to recruit staff and make sure shifts were properly manned.
Kurt Callaerts of the Christian union told VRT News: "Last week we noticed that several promises were not being kept. Shifts were not properly manned."
"The situation was compounded by a series of delays on Sunday. This triggered protests by staff members. We organised a staff meeting. Work came to a halt as a result and this led to delays for passengers."
The protest was at an end by 7:15 PM after the unions received new guarantees from the management.