52 mins is doable.......but be sure you wear your lucky underwear, go to confession before you leave, and hope they open an elite security line that day. The biggest challenge, as danville said, is going out of C&I in T6 then trying to go back thru security in T7.

Now, to UA's credit, I have been very lucky with a itinerary similar to yours. Schedule change cut our connection time way too close. The onward flight was 747, and we had 4 award seats confirmed in F/C. The later flight was only a 777, and checking on line, there were no upgrade seats available, and only a total of 4 seats were open. Considering the problem was caused by United's schedule change, they confirmed the 4 remaining F/C seats for us.