> Use "jdbc:firebirdsql:host/3050:path?lc_ctype=WIN1251" as JDBC URL.

Then print the characters you get from the database on the console as
integers. Something like:

String myString = rs.getString(1);
char[] chars = myString.toCharArray();
for(int i = 0; i < chars.length; i++) {
System.out.println("char[" + i + "] = " + (int)chars[i]);
}

If you get different character codes, then you ahve the problem with
Tomcat/Servlet/JSP that incorrectly converts them.

Roman