You can add optimistic locking capability to an entity bean using the @Version annotation:

@Entity
public class Flight implements Serializable {
...
    @Version
    @Column(name="OPTLOCK")
    public Integer getVersion() { ... }
}           

The version property will be mapped to the OPTLOCK column, and the entity manager will use it to detect conflicting updates (preventing lost updates you might otherwise see with the last-commit-wins strategy).

The version column may be a numeric (the recommended solution) or a timestamp as per the EJB3 spec. Hibernate support any kind of type provided that you define and implement the appropriate UserVersionType.