Narrative:

I was flying the leg into bwi which was operating on runway 15R. We were cleared to 2500 MSL; called the airport and in sight and were cleared [for] a visual approach by potomac approach. We were also directed to switch to tower frequency. I was approaching from the east on a vector to final which intercepted between bmore and kevvn. We were cleared the visual when the aircraft was at about 4000 MSL. We were at about 230 knots descending with flaps 5. Once cleared the visual I set the aircraft up to go direct to kevvn and selected 2100 in the altitude window. I announced and verified these changes with the captain; then executed. As we switched to tower the captain said 'those are big towers.' I was looking at the runway and changed my view in front of the aircraft. I saw 2 towers I believed to be the 1504 and 1437 ft towers depicted on the ILS 15R chart. We had a quick discussion. There were no GPWS warnings and nothing showing yellow on the terrain display. I made the comment 'I'm surprised there was no terrain caution or yellow.' I adjusted the path of the aircraft to intercept final inside kevvn keeping us well clear of the towers vertically and horizontally. The aircraft did not leave 2100 MSL until we were intercepting glide path and final course past the towers. As we had the discussion about the towers; bwi tower issued a low altitude alert and the altimeter of 29.79 (which had been set in the approach check). We completed a normal visual approach and landing with no incident. [Later] I researched the obstacles on the 15R approach chart. At no time were we closer than 500 feet vertically of the towers. We did not fly over them and remained clear. The captain became concerned after the flight and called the operations center. I am surprised the terrain database did not at least turn yellow on the display.

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Original NASA ASRS Text

Title: B737 flight crew reported receiving a low altitude alert from BWI Tower on the visual approach to Runway 15R; but did not receive an EGPWS warning.

Narrative: I was flying the leg into BWI which was operating on Runway 15R. We were cleared to 2500 MSL; called the airport and in sight and were cleared [for] a visual approach by Potomac Approach. We were also directed to switch to Tower frequency. I was approaching from the east on a vector to final which intercepted between BMORE and KEVVN. We were cleared the visual when the aircraft was at about 4000 MSL. We were at about 230 knots descending with flaps 5. Once cleared the visual I set the aircraft up to go direct to KEVVN and selected 2100 in the altitude window. I announced and verified these changes with the Captain; then executed. As we switched to Tower the Captain said 'Those are big towers.' I was looking at the runway and changed my view in front of the aircraft. I saw 2 towers I believed to be the 1504 and 1437 ft towers depicted on the ILS 15R chart. We had a quick discussion. There were no GPWS warnings and nothing showing yellow on the terrain display. I made the comment 'I'm surprised there was no terrain caution or yellow.' I adjusted the path of the aircraft to intercept final inside KEVVN keeping us well clear of the towers vertically and horizontally. The aircraft did not leave 2100 MSL until we were intercepting glide path and final course past the towers. As we had the discussion about the towers; BWI Tower issued a low altitude alert and the altimeter of 29.79 (which had been set in the approach check). We completed a normal visual approach and landing with no incident. [Later] I researched the obstacles on the 15R Approach chart. At no time were we closer than 500 feet vertically of the towers. We did not fly over them and remained clear. The Captain became concerned after the flight and called the Operations Center. I am surprised the terrain database did not at least turn yellow on the display.

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.