Some posts mention that the MD80 TOWS shall be checked before every flight. IMHO a level 2 safety shall catch a level 1 failure, but if the level 2 has to be checked is not doing the job for what was designed.
That is something else I was trying to get at... level 2 should be automatically checked not manually and engineered to fail-safe... and hence report problem if there is one or system is not working, or fails self-test.