Boeing was mentioned because all A320 carriers documents take air distance as 1500ft or 7sec to touchdown from threshold. But I found one Boeing carrier out of the three that I know were operating using 1000ft air distance while other two used 450mtrs or 1500ft. As mentioned in the SAFO 19001 to use 1000ft air distance pilots need to be trained to recognise 1000ft point, touch down and if unable then to go around. There are other conditions like RW marking of 1000ft. etc. My question is are these conditions mandatory or advisory. Because the carrier that's using 1000ft air distance had overrun problems including two fatals due to long landings. Offcourse it wasn't due to only 500ft but by a long way. But can carrier use 1000ft or four secs to touch down without fulfilling necessary requirements?