Flight deck interval management and delegated separation for equivalent visual operations
An emerging Next Generation Air Transportation System concept — Equivalent Visual Operations (EVO) — can be achieved using an electronic means to provide sufficient visibility of the external world and other required flight references on flight deck displays that enable the safety, operational tempos, and visual flight rules (VFR)-like procedures for all weather conditions. Synthetic and enhanced flight vision system technologies are critical enabling technologies to EVO. Current research evaluated concepts for flight deck-based interval management (FIM) operations, integrated with Synthetic Vision and Enhanced Vision flight-deck displays and technologies. One concept involves delegated flight deck-based separation, in which the flight crews were paired with another aircraft and responsible for spacing and maintaining separation from the paired aircraft, termed, “equivalent visual separation.” The operation required the flight crews to acquire and maintain an “equivalent visual contact” as well as to conduct manual landings in low-visibility conditions. The paper describes results that evaluated the concept of EVO delegated separation, including an off-nominal scenario in which the lead aircraft was not able to conform to the assigned spacing resulting in a loss of separation.
Is the B757 Really a "Heavy" Aircraft?
In July 1996, a new wake vortex category was created for the B757 which placed it between revised Large and Heavy categories. Shortly thereafter, the B757-300, stretched version of the B757-200, was placed in service and soon was treated by Air Traffic Control as a Heavy aircraft due to its maximum certificated takeoff weight. This study examines the behavior of vortices from both aircraft during approach/landing operations and shows little difference between the vortices of the two B757 series. In fact, both measurements and theory indicate that B757-300 vortices decay somewhat faster than B757-200 vortices. Therefore, the B757-300 is being penalized by unneeded increased wake vortex spacing during approach/landing operations.
Euthanasia — again: “Letting die” is not in the patient's best interests: a case for active euthanasia
Recent discussions in the Journal on the subject of euthanasia have relied on intuitive appeals to distinctions traditionally considered to be morally relevant, such as the distinction between acts and omissions (or killing and letting die), or ordinary and extraordinary means of treatment. These discussions remained inconclusive. However, the question of euthanasia no longer remains inconclusive if one adopts the perspective suggested by the United States President's Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research and by the World Medical Assembly – that a doctor should act in his or her patient's best interests. From this vantage point, it is argued, there will be instances when active euthanasia is the proper cause of action.