Incident at TORONTO / LESTER B. PEARSON INTL ON (CYYZ) (ATM - other)

1996-09-26: Beginning at 1931Z, the ILS for runway 06R glidepath failed numerous times, yet technicians reporte the system operating normally. Problem was thought to be caused by the MONCO. At 2045Z, due wind forecast, decision was made to arrive 24L/R. At 2230Z, the 24L glidepath failed and the ACC was advised it would be some time before it was brought back up. At 2305Z, the 24L localizer failed. At 2320Z, a decision was made to return to 06L/R. The ILS was turned on prior to the changeover and worked normally. Before the first arrival was turned to final for 06R, a request was made to try the 24L localizer. It functioned satisfactorily. When 06R ILS was reselected, difficulty was experienced. At 2328Z, the 06R ILS was reported on. At 2333Z, the 06R glidepath failed according to the ILS MONCO yet OIDS reported normal functioning. At 2336Z, the ILS for 06R was reported normal by the MONCO and verified by a technician. Ops. Impact -- no delays to the users.