What does it indicate if the LAVS INOP indicator illuminates?

When the LAVS INOP indicator illuminates, it indicates that the tank has become full. This means that the aircraft's lavatory waste system is unable to process any more waste, and therefore the lavatories may be rendered inoperable until the tank is emptied. Recognizing this signal is crucial for cabin crew and maintenance personnel to ensure passenger comfort and hygiene.

While the other choices may pertain to various maintenance or operational issues related to the aircraft, they do not directly correlate to the LAVS (Lavatory Service) system malfunction indicator. The other options reflect situations that would not specifically trigger this particular alert, further emphasizing the importance of understanding the relationship between system indicators and their meanings.