INVENTORIES

The majority of our inventories are for business-jet aircraft. Our inventories are stated at the lower of cost or net realizable value. Work in process represents largely labor, material and overhead costs associated with aircraft in the manufacturing process and is based primarily on the estimated average unit cost in a production lot. Raw materials are valued primarily on the first-in, first-out method. We record pre-owned aircraft acquired in connection with the sale of new aircraft at the lower of the trade-in value or the estimated net realizable value.

Inventories consisted of the following:



	March 31, 2019		December 31, 2018
Work in process	$	4,510	$	4,357
Raw materials	1,535		1,504
Finished goods	45		33
Pre-owned aircraft	95		83
Total inventories	$	6,185	$	5,977

The increase in total inventories during the three-month period ended March 31, 2019, was due primarily to the ramp-up in production of the new G600 aircraft in our Aerospace segment, for which we are anticipating FAA type certification and entry into service in 2019.