Date: 201702
Local time of day: 1201-1800
Location: BWI.Airport, MD
Light: Daylight
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Approach
Airspace: Class B BWI
ATC / advisory: Tower BWI
Aircraft component: GPWS
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Second reporter function: Pilot Not Flying; Captain
Anomaly: Aircraft Equipment Problem Less Severe; Inflight Event / Encounter CFTT / CFIT
Detector: Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Ambiguous

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.


Second narrative: We were cleared for the visual approach Runway 15R. We were between the fix BMORE and KEVVN and at 2300. I felt we were going too close to the tower at 1504 feet with the arrow on top. We climbed back a few hundred feet and passed the tower on the right side of the aircraft. The EGPWS never went off and we did not have a yellow warning on our navigation display. BWI Tower got a low altitude alert.


Synopsis: 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.