Today’s Indy Bump Day explained

Any qualifying attempt on the fourth day (Bump day) that is faster than a qualified entrant in the 33 positions in the starting field will bump the slowest qualifier from the field. The “bumped" entrant will be removed from the field of 33, and the remaining field will move ahead one position in the starting field as the newly qualified entrant will take the 33rd position, or a higher position if faster than the other fourth day qualifiers.