B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 184; Flight Crew Type 12000
Aircraft Equipment Problem Less Severe
General None Reported / Taken
Aircraft; Procedure
This report is submitted to draw attention to questionable MEL guidance. Aircraft was operating under MEL because the 'F/O's ADI runway flag was always in view' according to the original discrepancy as entered in the logbook. We observed that the flag was indeed in view when the F/O had a LOC frequency tuned. And; the airplane was restricted to RVR 4000 or 3/4 mile minimums; per the MEL. My question is whether it would be safe to fly an IMC approach at all? With the runway flag in view; we do not know if the LOC signal is valid. How can the F/O provide reliable LOC deviation callouts on the Captain's leg if he may not be seeing accurate LOC guidance? Perhaps it would be safer if the F/O flew ILS or LOC approaches and the Captain; as PM; could provide sufficient safety monitoring. That way the F/O could fly the LOC as shown on his instruments despite the flag in view; and the Captain would have safe indications from which to provide monitoring? I think this MEL should be changed to limit the aircraft to a visual approach with the LOC flag in view.
B737 Captain questioned the safety of an MEL he was dispatched with that left them with the First Officer's ADI runway flag in view at all times.