Many companies which operate under a just-in-time or "JIT" inventory method often use on-board couriers (OBCs). On-board couriers are individuals who can travel at a moment's notice anywhere in the world, usually via commercial airlines. While this type of service is the second costliest—general aviation charters are far more expensive—companies analyze the cost of service to engage an on-board courier versus the "cost" the company will realize should the product not arrive by a specified time (an assembly line stopping, untimely court filing, lost sales from product or components missing a delivery deadline, loss of life from a delayed organ transplant).