The 1170 WCOV DA-D facility was indeed built decades before Hanceville came on the air. 50 years ago I could name every station in Alabama with its power and freq. I knew WCOV was DA-D then. I'm sure it could have gone non-DA-Day before 1986, but it cannot now because of Hanceville. It protects Hanceville now; it did not protect it back when the facility was planned. I think the consultant is not making himself clear on that subject. Hanceville was able to shoe-horn its facility in because Montgomery already had the null decades earlier.
I have known of stations that built a DA to protect a CP that never came on the air, and the station continued to be DA for years after that. Two examples: WABF 1220 in Fairhope (where I live) came on in 1960, protecting 1220 in Monroeville, which changed to 1360 perhaps a year later. WABF continued to protect this non-existent station until about 7 years ago. WMOO 1550 Mobile, 2 tower 50 kw-D came on the air in 1964. It had a null to the NE to protect a Selma station which had a CP to move from 1570 to 1550. Selma stayed on 1570, and WMOO kept that NE null until it moved to 660 around 1990.
I have known of other owners who did not know the true nature of their DA situation.
WABF and WMOO, both located on the eastern shore of Mobile Bay, got some benefit from their DA in that they pushed more signal into Mobile proper, though they lost some other areas. Think of the DA as a balloon ... you squeeze it in at one place, and it bulges out in the other.
Sometimes you choose a DA to focus more signal in an intended area. We no longer have Class 1-A clear channel stations, but two of them - WWL 870 New Orleans and WBZ 1030 Boston, chose to be DA-1 to redirect signal that would go out into the water (Gulf of Mexico and Atlantic Ocean respectively), back over land with ERP greater than 50 kw. Come to think of it, 1100 Cleveland (KYW/WTAM/WKYC) did the same at one time, reducing its signal into Canada (they've since gone non-DA). It wasn't about protecting some other station, because there were no other stations on their freq.
The WACV/WCOV DA-D increases the signal more to the East and West than South; maybe they were trying to be listenable in Selma and Columbus. Who knows what they were thinking 50+ years ago (the station was originally on 1240, moved to 1170 way back when).
The main reason AM stations go DA is because they have to avoid interfering with an existing station; sometimes it's to increase signal in a certain direction, as mentioned above. A third, infrequently invoked reason, is because at one time the FCC would not let you own two stations with contour overlap (we've come a long way since then). I once heard of a station having to implement a DA because its non-DA signal would have prohibited overlap with another station (on an entirely different frequency) that it also owned. WVOK 690 and WBAM 740 (once commonly owned) were both DA for other reasons, but I once heard that if both had been non-DA, their 0.5 mv/m contours would overlap significantly between Montgomery and Birmingham.
