This may seem inconsistent, but it’s the law in Stephenworld: your database does need to know who flew last October 29th’s United 277, but it does not need to know what runway United 277 might have had reserved on that date — all that it needs to know about runway reservations is what runways are currently reserved. (In other words, information about flight crew assignments must be kept in perpetuity, whereas your database only needs to know what current flight has each runway reserved, if any.)