special attempt has the following criteria.
1. Reason as to why u need to give an exam in the special attempt (Recency lapsing etc.)
2. Only if you have rest of the papers passed except just One left.
In addition, CEO conducts ‘Special Examinations’ to facilitate candidates to complete their written examinations so that they can fulfill the requirements for issue of license as per Aircraft Rules. These Special Examinations are conducted for those candidates who have completed all requirements for issue of Pilots License except passing of one written paper. These special examinations shall be conducted in the month of March, June, September and December each year or as may be decided by Director General from time to time . The information regarding the dates of examination is given on the DGCA website.
http://dgca.nic.in/cars/D7B-B1.pdf