Altro commento, stavolta da A.Net, che trovo particolarmente interessante (e che risponde anche ad alcune delle questioni poste da CTALIRQ):
This is just brutal. I can’t believe what I’m seeing. Absolutely still processing but, just a couple thoughts as a captain who’s in DCA constantly…
TCAS is inhibited on the CRJ below 1000 feet. This is by design, as the aircraft is too low and slow to maneuver. The PSA crew would not have gotten a traffic resolution advisory.
Runway 33 is a complex landing. Not difficult, but complex. It requires more of a crew’s attention, so they likely wouldn’t have had much extra time/brain bandwidth to scan for traffic.
Helicopters are frequently on another frequency in DC. The CRJ crew may never have been aware another aircraft was even maneuvering in their vicinity.
From altitude, lights are not easily discernible. They blend into the background of lights on the ground. Even with bright landing lights on, from that angle it’s not as obvious as one might think.
“Visual separation” is a prescribed procedure. Accepting it, as the helo did, absolves ATC of responsibility for separating the 2 aircraft.