Do we remove the MEL or expect engineers and pilots to understand every problem that can exist on an aircraft and judge every MEL item with their limited information.
MELs are produced by factory engineers to allow aircraft to fly with certain bits inop.
When the MD-80 RAT Heat MEL was written up it allowed flight with no forecast icing conditions. Simple, and no problem so far. Pull the RAT Heater circuit breaker and off you go. Crucially, what wasn’t considered by the MEL writers was
why the RAT might Heat on Ground. A failure of Relay R2-5 (Flight Mode) would do it – which would also disable the TOWS. So, pull the RAT Heat circuit breaker, RAT Heat problem fixed, TOWS is now inop with NO indication of failure. And I defy any line engineer, no matter how smart, to raise his hand and say “Hold on guys, RAT Heat on, I bet R2-5s failed and we can’t just pull the RAT breaker because the TOWS might also be inop”. That’s down to the MEL actions and, from what I’ve seen in this case, they ain’t up to the job.
This accident has been waiting to happen from the day the aircraft left Long Beach. Very poor TOWS/Flight/Ground logic design, and very poorly written MEL.