The 321 is filling in for a replacement 733 which is due late in the summer. However, It is my understanding that it is staying for the majority of the summer season. Baby are booking the flights scheduled to be operated by the 321 for the 321s capacity. I'm not sure if they know in advance big brother might switch it to a 319 ! The 321 is doing the fllights it is doing because MAN can take the additional capacity on those routes during the summer season and the business is seriously looking at this potential.