In this entire thread, the above is the first reference I can find to '180 at 5' and is from Post #1353 (page 68 currently), an NTSB briefing summary by Knot Apilot.
You can find the actual verbiage from Debbie Hersman's July 9, 2013 NTSB briefing here at about 15:10 in the clip:
C-SPAN
The 160 knot landing flap limit cited by Ms. Hersman seems low to me, as discussed earlier, perhaps this is not correct.