Enhanced Low Visibility Operations — Increasing flight operations services in the National Airspace System in low visibility conditions

Abstract

Aircraft landing and taking off in low visibility is a critical area for aviation and the aviation industry. Flights can be cancelled, diverted, or delayed if aircraft cannot land or take off in low visibility. This impacts all users and stakeholders of the National Airspace System (NAS), including passengers. Low visibility can develop from weather or fog, causing air traffic to move from Visual Meteorological Conditions (VMC) under Visual Flight Rules (VFR) to Instrument Meteorological Conditions (IMC). During IMC, aircraft are under Instrument Flight Rules (IFR) and only those aircraft that appropriately equipped with appropriately trained crews can continue operations. If aircraft could be equipped such that flight operations could continue for a longer period of time while conditions are worsening, more operations could continue to land rather than divert or take off rather than wait for conditions to improve. In a combined effort, and as part of the Next Generation Air Transportation System (NextGen), the FAA is in the initial stages of implementing increased low visibility capabilities in an effort initiated and led by FAA Flight Standards and supported by Navigation Services. Prior to this work, Standard Category (CAT) I, CAT II, and CAT III were available. Minima are defined by the Runway Visual Range (RVR) system. New levels of service include take offs with a minimum as low as 500', as well as landing operations that include RVR 1800 (vice RVR 2400), Special Authorization (SA) CAT I, and SA CAT II. As will be discussed, this allows for advantages such as lower RVR-defined minima, lower Decision Altitude (DA), and for SA CAT II, lower life cycle costs for the infrastructure over the Standard CAT II services. The updates to FAA Order 8400.13, “Procedures for the Evaluation and Approval of Facilities for Special Authorization Category I Operations and All Category II and III Operations” allow for these additional categories of service. In an oversimplification, Flight Standards grants operational credit for equipage such as the Head Up Display (HUD) and Autoland so that such aircraft suitable equipped can continue with operations in conditions where other aircraft may have to be diverted. In many cases are obtained through publication of a new procedure, or in other cases may require some minimal ground infrastructure changes or enhancements, such as an additional Runway Visual Range (RVR) sensor or upgrade to the Instrument Landing System (ILS). What is arguably a particular advantage is that less lighting is required for these services.