Narrative:

On a 4 mi final with the runway in sight, the tower controller informed us of a 'low altitude alert' in the vicinity of the FAF. We were in level flight and on course with the VASI coming into view. Everything looked correct. However, during the approach, a constant flight director aural voice states 'GS, GS,' which is stated on the commercial chart for the localizer runway 24 back course. The note states 'ignore GS indications.' also, a recent NOTAM states, required radar only fixes and that DME approachs are 'not applicable from feeders.' approach was flown in VMC, however, I wouldn't option to fly this non precision approach with less than 3 mi visibility. However, the company commercial special 10-0 page states 'you may receive a GPWS warning and to execute an immediate go around if terrain isn't vdp visible. Also, the tower low altitude alert may be triggered due to the altitude rate or change to descend from the FAF altitude to the MDA by the vdp. Callback conversation with reporter revealed the following information: reporter is very concerned that in this situation all of the warnings -- low altitude alert from abe tower, GPWS verbal warning (most likely activated from the front course of this back course approach), and the FAF idented on the approach plate by a slant range from a VOR 16.9 NM away -- all combine to produce a very hazardous condition for all air crewmen. On this incident, the reporter is a check airman for the air carrier and was working with a new hire with the additional burden of a slight language problem and this helped to point out the potential hazards of this situation. The air carrier does a good job of providing a tailored commercial chart 10-1 page that points out many of these hazards and adds a measure of safety.

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Original NASA ASRS Text

Title: RPTR OF B737 POINTS OUT DANGEROUS CONDITIONS OF BACK COURSE 24 APCH PROC INTO ABE.

Narrative: ON A 4 MI FINAL WITH THE RWY IN SIGHT, THE TWR CTLR INFORMED US OF A 'LOW ALT ALERT' IN THE VICINITY OF THE FAF. WE WERE IN LEVEL FLT AND ON COURSE WITH THE VASI COMING INTO VIEW. EVERYTHING LOOKED CORRECT. HOWEVER, DURING THE APCH, A CONSTANT FLT DIRECTOR AURAL VOICE STATES 'GS, GS,' WHICH IS STATED ON THE COMMERCIAL CHART FOR THE LOC RWY 24 BACK COURSE. THE NOTE STATES 'IGNORE GS INDICATIONS.' ALSO, A RECENT NOTAM STATES, REQUIRED RADAR ONLY FIXES AND THAT DME APCHS ARE 'NOT APPLICABLE FROM FEEDERS.' APCH WAS FLOWN IN VMC, HOWEVER, I WOULDN'T OPTION TO FLY THIS NON PRECISION APCH WITH LESS THAN 3 MI VISIBILITY. HOWEVER, THE COMPANY COMMERCIAL SPECIAL 10-0 PAGE STATES 'YOU MAY RECEIVE A GPWS WARNING AND TO EXECUTE AN IMMEDIATE GAR IF TERRAIN ISN'T VDP VISIBLE. ALSO, THE TWR LOW ALT ALERT MAY BE TRIGGERED DUE TO THE ALT RATE OR CHANGE TO DSND FROM THE FAF ALT TO THE MDA BY THE VDP. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR IS VERY CONCERNED THAT IN THIS SIT ALL OF THE WARNINGS -- LOW ALT ALERT FROM ABE TWR, GPWS VERBAL WARNING (MOST LIKELY ACTIVATED FROM THE FRONT COURSE OF THIS BACK COURSE APCH), AND THE FAF IDENTED ON THE APCH PLATE BY A SLANT RANGE FROM A VOR 16.9 NM AWAY -- ALL COMBINE TO PRODUCE A VERY HAZARDOUS CONDITION FOR ALL AIR CREWMEN. ON THIS INCIDENT, THE RPTR IS A CHK AIRMAN FOR THE ACR AND WAS WORKING WITH A NEW HIRE WITH THE ADDITIONAL BURDEN OF A SLIGHT LANGUAGE PROB AND THIS HELPED TO POINT OUT THE POTENTIAL HAZARDS OF THIS SIT. THE ACR DOES A GOOD JOB OF PROVIDING A TAILORED COMMERCIAL CHART 10-1 PAGE THAT POINTS OUT MANY OF THESE HAZARDS AND ADDS A MEASURE OF SAFETY.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.