Routes- are they assigned or determined on seniority bids
 

Do the following airlines assign what route who will fly and when or do they let pilots bid on routes on the basis of seniority; the airlines in question-

Singapore Airlines

Thai Airways

Air India

Sri lankan

Thanks for your reples;

Lastly what context is the term crew rostering used in?

SriLankan

Can't say just now, but when I worked there (1990's) the rosters were assigned, however pilots could make requests (and trade flights) which were nearly always granted.

Local Captains liked LHR but generally dis-liked NRT so personally received many more NRT flights. The system seemed to work pretty well and most everyone was satisfied.