Date: 201811
Local time of day: 0001-0600
Location: ZZZ.Tower, CA
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Final Approach
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Reporter organization: Government
Reporter function: Other / Unknown
Reporter qualification: Air Traffic Control Fully Certified
Anomaly: ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter CFTT / CFIT
Detector: Automation Aircraft Terrain Warning; Automation Air Traffic Control; Person Air Traffic Control
Result: Air Traffic Control Issued Advisory / Alert
Contributing factors: Procedure; Human Factors
Primary problem: Human Factors

Narrative: I was not involved in the event; however; I'd be remiss if I didn't report what happened. I became aware of a safety event where Aircraft X; an E145; came dangerously close to terrain to the northeast of ZZZ.Aircraft X checked in on frequency on a visual approach using the wrong flight number. He was on a visual approach. LC [Local Control] corrected the call sign. LC apparently noticed that he was extending downwind and was low. LC asked if he was going to turn base and during his snarky response; you could hear the GPWS [Ground Proximity Warning System] alert in the cockpit and his scared response to it as he said 'Pull up' repeatedly before he unkeyed his mic.This is extremely concerning as Aircraft X is a scheduled air carrier new to this airport. His attitude during his transmission seemed inconsistent with a professional operation. So too seems the attitude of the Controller working the situation. I admit that the Controller did say something about it; but I can only imagine that the reason was due to the MSAW [Minimum Safe Altitude Alerts Warning] LA [Low Altitude] alert; and not due to actual knowledge of the seriousness of the situation. This Controller is known for making remarks in the background when TRACON issues low altitude alerts over the shout line for aircraft on visual approaches. Things like 'They're on a visual approach' with attitude; implying that such an advisory constitutes a pointless annoyance. Those calls are required by their SOP and are designed to prevent this exact type of thing! Even though an aircraft is on a visual; it is entirely possible that they can descend too low; particularly in an unfamiliar area; and at night.Proper 'Low altitude alert' phraseology was not used. The EOVM [Emergency Obstruction Video Map] shows the height of the small mountain in that area to be 1;700 feet. Aircraft X was at 1;800 feet.The situation was not reported; even though it meets criteria for a report. I later found out that this was an intentional effort to 'Sweep it under the rug.'In my opinion; this incident illustrates a frightening lack of professionalism on both sides; which came seriously close to disaster. I'm speechless.Unfortunately; I'm not sure how to fix something like this. Hopefully this will find its way to the hands of somebody who does.




Synopsis: Tower Controller reported an unsafe situation relating to an aircraft in close proximity to a small mountain and another controllers attitude relating to the situation.