B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 245; Flight Crew Type 8000
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Gate; General Maintenance Action
Aircraft; MEL; Procedure
After pushback; we ran the Before Taxi Checklist. Setting flaps to 1 we did not get a green light; only a flap transit light. We noticed that the number four leading edge device was not showing transit position on the overhead panel but did show green overhead along with the rest of the flaps/slats. We ran the QRH; but as we read the QRH the transit light went out and the green LE Flaps EXT illuminated. We had all green on the overhead and green light on the forward panel. We continued our taxi and during taxi the forward green light went back to amber in transit again. We notified Maintenance Control and returned to the gate. MEL Leading Edge Slat Indications Forward Panel and number four slat was applied. We read the MEL and began our second pushback. In the MEL; the list of procedures section A is to verify leading edge slat position for the inoperative indication before each takeoff and landing. Then the MEL has a note to use the wing illumination light to verify normal operation of leading edge; which (to me) means that I must visually see the slat from the cockpit. My First Officer could not see slat number four from the cockpit view. He could see slat number five and number six. I looked out my window and I also could not see slat number three (it's slat three on the number one engine that corresponds to the number four slat on the number two engine) from my vantage point on my wing. The MEL goes on to say all indications on the overhead annunciator panel must be operating normally. The MEL says all items must be complied with so we both concluded that we could not comply with the MEL so we returned to the gate. The only way my First Officer could possibly see the number four slat was by opening his window and sticking his head out to verify. We knew we would be unable to do this in flight. The other option was to go back and look through the passenger window; but on landing you're in a critical phase of flight; so we concluded that was not an option either. My Dispatcher; Chief Pilot on Call; and Maintenance Control were notified as to our decision. My opinion is the MEL should be fixed. If the number four slat is affected; this MEL cannot apply or verify the slat position using the overhead only.
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B737 flight crew reported they could not comply with MEL procedure to verify leading edge flap position in flight because they could not see the device from the cockpit.