Reading over locked rows

Hi, i've a program which unload tables to an ascii file and updates a specific column in the rows after they are written to the file. Isolation mode is set to repeatable read to avoid rows to be written to the file which are not committed. Everything was fine but if there are open transactions over some rows of a table i got repeated errors in the range -242 to -246 (depends if the table is indexed or not) until all transactions for this table are completed. Is there a way to "jump" over the locked rows? Greetings, Joerg