Ferris, I totally agree, the Mark I eyeball is the primary tool to be used for spotting traffic. But for 2 pilots to be continually scanning outside for about a minute with neither looking in at any of the displays (I am in no way suggesting this is what happened incidentally-that is what investigations are for) is a bit strange.
I am aware of the limitations on TCAS thank you. But if it wasn't supposed to be used to increase SA and assist in traffic spotting, why does it display aircraft +-2700', with later some systems giving you an option of +-10 000'? It may not have been it original purpose, but it sure does help spot aircraft. I guess it's like the GPS system. The US DoD originally designed it to guide cruise missiles onto enemy targets, not for lighties to conduct GPS approaches. Not the original design concept but very useful nevertheless.
I fly a high performance jet into some extremely busy MBZs and CTAFs and have found it incredibly useful. Yes some aircraft are not shown but it certainly assists finding the majority.