No. All planes that do not belong to this around (ie production withdrawn in year 1999 and before or production begin later than the in-game date, both according to the AM database) should NOT be used. Otherwise, you are begging for discipline. This has been repeated 3 times in different threads (by me... although not an admin, but consider these warnings from StephenM).
These planes include, but not limited to, Concordes, Comets, Viscounts, F-27s, B707s, B732's, A300B2's.
Please drill that into your heads and don't scream unfair in the forum when disciplinary actions are taken. Take the routes and leases and anything off them NOW!