<a href="http://www.fsis.usda.gov/OA/pubs/tbcook.htm">FOOD SAFETY FACTS Turkey Basics: Safe Cooking </a>: Many factors can affect the roasting time of a whole turkey:
- A frozen or partially frozen turkey takes longer to cook than a completely thawed turkey.
- A turkey will cook faster in a dark roasting pan.
- The depth and size of the pan can affect heat circulation to all areas of the turkey.
- The use of a foil tent for the entire cooking time can slow cooking.
- Putting a lid on the roasting pan speeds up cooking.
- An oven cooking bag will shorten cooking time.
- A stuffed turkey will take longer to cook than an unstuffed turkey.
- Ovens may heat unevenly.
- The oven rack position can have an effect on even cooking and heat circulation.