Perplexing Autopilot Discrepancy in C-130 Technical Posted April 29 That seems like it is using the valid signal to turn on the the Capture light, and not deviation. When you do the TACAN and VOR, do you have the HSI course bar centered before you hit the L/NAV switch? If it wasn't< iwould think the A/P would drive the yoke hard one way or another. I will send you a message and give you my e-mail address. We can converse that way. Maybe if it gets solved we can post what the problem was.