Narrative:

I was the pilot flying the bhm RNAV (GPS) runway 36 approach. We were cleared direct to gotby (IAF) at or above 3;000 ft for the GPS runway 36. At gotby we stepped down to 2;800 ft to imoby; then down to 2;300 ft to berfy (FAF). We were handed off and checked in with tower outside berfy. The tower cleared us number 1 to land runway 36. Two minutes later the tower issued us a 'low altitude alert' and advised us to check our altitude immediately. At that time we were slightly above the MDA of 1;480 ft. I continued for a few more seconds until the aircraft issued an 'obstacle; obstacle' alert and the mfd indicated a yellow shaded circle directly in front of the aircraft. I again noted my altitude was correct at 1;500 ft however executed an immediate missed approach as we were solid IMC and there was no way to visually verify the situation outside the aircraft. We were issued a climb to 4;000 ft and vectored instead for the bhm ILS 24 approach to a landing. Perhaps of some relevance was that the aircraft that was following us on the bhm RNAV (GPS) runway 36 approach; a cessna sovereign; was also issued a 'low altitude alert' two minutes after mine; and advised to check their altitude immediately. As it's not clear why the taws indicated 'obstacle; obstacle' during this approach I cannot suggest how to avoid this in the future. We are required at night to utilize the taws screen on the mfd at night; but given the variety of airports we fly to in less than VFR conditions; it may be advisable to utilize the taws screen at all times in the terminal area at night or when IMC exist.

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Original NASA ASRS Text

Title: Turboprop pilot reports being issued a low altitude warning by the BHM Tower while at minimums on the RNAV (GPS) Runway 36. Within a few seconds the aircraft TAWS system issued 'OBSTACLE' alert and the MFD indicated a yellow shaded circle directly in front of the aircraft. A go-around is initiated; followed by an approach to a different runway. It was reported that the following CE680 was issued the same warning by the Tower.

Narrative: I was the pilot flying the BHM RNAV (GPS) Runway 36 approach. We were cleared direct to GOTBY (IAF) at or above 3;000 FT for the GPS Runway 36. At GOTBY we stepped down to 2;800 FT to IMOBY; then down to 2;300 FT to BERFY (FAF). We were handed off and checked in with Tower outside BERFY. The Tower cleared us number 1 to land Runway 36. Two minutes later the Tower issued us a 'Low Altitude Alert' and advised us to check our altitude immediately. At that time we were slightly above the MDA of 1;480 FT. I continued for a few more seconds until the aircraft issued an 'OBSTACLE; OBSTACLE' alert and the MFD indicated a yellow shaded circle directly in front of the aircraft. I again noted my altitude was correct at 1;500 FT however executed an immediate missed approach as we were solid IMC and there was no way to visually verify the situation outside the aircraft. We were issued a climb to 4;000 FT and vectored instead for the BHM ILS 24 approach to a landing. Perhaps of some relevance was that the aircraft that was following us on the BHM RNAV (GPS) Runway 36 approach; a Cessna Sovereign; was also issued a 'Low Altitude Alert' two minutes after mine; and advised to check their altitude immediately. As it's not clear why the TAWS indicated 'OBSTACLE; OBSTACLE' during this approach I cannot suggest how to avoid this in the future. We are required at night to utilize the TAWS screen on the MFD at night; but given the variety of airports we fly to in less than VFR conditions; it may be advisable to utilize the TAWS screen at all times in the terminal area at night or when IMC exist.

Data retrieved from NASA's ASRS site 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.