A B727-200 FLC RPTS THAT A 465 FT TWR LOCATED NEAR THE LOC BACK COURSE CTRLINE IS NOT INDICATED ON THE PUBLISHED APCH PROC. THE FLC HAD INADVERTENTLY DSNDED BELOW THE MDA WHILE IN A NON PRECISION APCH DSCNT AND NOTICED THE TWR (PWR LINE) AS IT PASSED UNDER THE R WING. THE RPTR ALLEGES THAT OTHER CREWS MAY BE SIMILARLY CAUGHT IN THIS SIT AS A RESULT OF THE COMBINATION OF THE APCH DESIGN AND THE SHORT RWY AT BTR.

Narrative

I WAS THE PNF ON A LOC (BACK COURSE) APCH TO RWY 4L AT BTR. WX WAS CLR BELOW 12000 FT AT THE FIELD; BUT 3000 FT OVCST JUST TO THE S. THE IAF ALT IS 2100 FT AT 5.5 MI S OF THE FIELD. PASSING THE IAF WE STEPPED DOWN TO 720 FT WHICH WAS THE INTERMEDIATE ALT TO 2.0 MI. AUTOPLT RESTRS REQUIRE THIS PORTION OF THE APCH TO BE HAND FLOWN WITH A GOOD SINK RATE (1300-1500 FPM) TO LOSE 1380 FT IN 3.5 MI. PF WENT THROUGH THE INTERMEDIATE ALT BOTTOMING OUT ABOUT 660 FT AS WE BROKE OUT APPROX 2.2 MI S. TWR CALLED US IN SIGHT AND ASKED US IF WE COULD SEE THE FIELD; STATING HE WAS GETTING A LOW ALT ALERT. WE REPLIED FIELD IN SIGHT AND WERE CLRED FOR THE VISUAL APCH. WE WERE IN A SLIGHT CLB PASSING THE FAF AT 2.0 MI WHEN I NOTICED A VERY LARGE PWR LINE PASSING UNDER THE R WING. IT GOT MY ATTN. IT IS NOT DEPICTED ON THE PLATE BUT IS REFLECTED ON ALL THE OTHER BTR PLATES WHERE IT IS NOT NEARLY AS SIGNIFICANT. A STABILIZED APCH REQUIRES A VDP APPROX 1.7 MI S FROM 580 FT. EVEN UNDER IDEAL CONDITIONS THIS APCH IS TIGHT AND DOES NOT ALLOW FOR ANY DEVS. MY GUESS IS THAT MORE THAN 1 CREW HAS BEEN TEMPTED TO STEP DOWN A LITTLE EARLY SO AS TO BE COMFORTABLY STABILIZED AT THE VDP. IN ADDITION TO THE TIGHT APCH; THE SHORT RWYS DO NOT LEND THEMSELVES TO BEING HIGH OR FAST AT THE FAF. NOT HAVING A CRITICAL PIECE OF INFO (465 FT TWR ON CTRLINE) ON THE PLATE IS NOT GOOD; AND POTENTIALLY CATASTROPHIC. IN OUR CASE THE REMAINDER OF THE APCH AND LNDG WAS UNEVENTFUL. I ESTIMATE WE FLEW OVER THE PWR LINE AT ABOUT 680 FT MSL. AT A MINIMUM I THINK THIS APCH SHOULD BE REVIEWED; THE PWR LINE DEPICTED ON THE CHART; AND A NOTE ENTERED IN THE SPECIAL PAGES. I DOUBT THAT WE WERE THE FIRST CREW TO HAVE THIS EXPERIENCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVOCATES PLACING THE OBSTRUCTION ON THE APCH PLATE AND REVIEWING THE PROC'S TERPS COMPLIANCE. THE VISUAL DSCNT POINT CITED IN THE NARRATIVE IS NOT PUBLISHED ON THE IAP; BUT IS A PROC THAT THE RPTR LEARNED IN TRAINING. THE MDA (AGL) FIGURE IS DIVIDED BY 3; FOR A 300 FT PER NM DSCNT TO THE RWY FROM THE VDP.