It would be completely dependent on the employer. Some airlines are very good with sick leave (a certain Dutch airline provides superb support to its staff in times of sickness, but that's perhaps due to more comprehensive Dutch employment law?). A certain low-cost carrier based in the north of England gives you ZERO in terms of sick pay during your first year, and not a right lot after that. Fine, there's always statutory sick pay, but that's a joke.
It's a how-long-is-a-piece-of-string question really. The package will differ depending on who you were to work for. You may wish to search the terms and endearment forum for sick pay and see what turns up.