Originally Posted by
WineCountryUA
I see NF, NC, XF, XC, XY & NY for the flights you mention
Note these are only visible if doing an award / mileage booking
Take a look a UA 946 LAX-IAD 10/1
UA 846 IAD-EZE 10/1
Booking codes F/P/A/C/D/Z/Y/P/B/E/M/U/H/Q/V/W/T/S/K/L/G