It looks likely the game will be staged on Monday March 7, just two days after Arsenal play the north London derby against Tottenham at White Hart Lane and despite Hull having a Championship game against Brentford scheduled for the following day.
The tie cannot be played midweek because it would clash with UEFA competitions, which could result in a big fine for the FA.
It is thought there is little appetite to play it on sixth round weekend because of the potential knock-on effects later in the competition, like trying to fit in more replays.
There are still no dates for the three quarter-finals that can be arranged – Reading v Crystal Palace, Everton v Chelsea and West Ham’s visit to Manchester United.
Fans of the east London club are already applying for tickets and some United fans have paid for theirs.
The games are due to be played over the weekend of March 11-14, but problems around TV scheduling and the fact the Old Trafford outfit could be playing Europa League games on March 10 and 17 mean no dates have been finalised.