International Civil Aviation Organization FLTOPSP/WG/2-WP/11 24/04/2015 WORKING PAPER FLIGHT OPERATIONS PANEL WORKING GROUP SECOND MEETING (FLTOPSP/WG2) Rome, Italy 4 to 8 May 2015 Agenda Item 6: Any Other Business Type B Instrument Approach Operations to 150 Feet Decision Height (Presented by Mr. Chris Hope) SUMMARY This paper proposes additional guidance material that is necessary to implement ICAO guidance and design criteria for Instrument Approach Procedures (IAP) with a Decision Height (DH) of 150 feet based on work performed in the All Weather Operations Harmonization Aviation Rulemaking Committee (AWOH ARC) 1. INTRODUCTION 1.1 There is presently no ICAO guidance material available to accommodate the use of 3D Type B approach operations to 150 foot Decision Height (DH). Some states currently conduct precision approach instrument procedures to 150 feet with the use of a Head-Up Display (HUD). Additionally, new hybrid technology incorporating vision systems and advanced guidance is encouraging states to seek minima lower than the historical and arbitrary 200 feet. There is no current ICAO guidance for the operation of such systems. 2. BACKGROUND/DISCUSSION 2.1 The Instrument Landing System (ILS) has been the mainstay of landing navigation aids for well over 50 years. The first landing of a scheduled U.S. passenger airliner using ILS was on January 26, 1938, when a Pennsylvania Central Airlines Boeing 247D flew from Washington, D.C., to Pittsburgh, Pennsylvania, and landed
in inclement weather guided only the Instrument Landing System. ILS was accepted as a standard system by the ICAO in 1947. The initial steps toward achieving the current CAT I operating minimums was taken on September 28, 1961. Prior to this time, turbojet minimums were 300 ft ceiling and ¾ statute miles visibility. The first air carrier operations with minimums of a ceiling of 200 ft. and a visibility of 1/2 statute miles were authorized on May 11, 1962. The concepts developed to permit this reduction in operating minimums established the foundation for a building block approach. With this approach operations evolved in an orderly manner as airborne and groundbased capabilities improved. The 1962 reduction in minimums to a ceiling of 200 ft. and 1/2 statute mile visibility was based on further improvements of airborne equipment, electronic ground-based navigation aids (NAVAID s), ground-based visual aids and enhanced pilot training and qualifications. In 1964, the minimums for runways not equipped with a high-intensity touchdown zone and runway centerline lights were reduced to 200 feet DH and RVR 2400. The modernized versions of the ILS used worldwide today continue to provide aircraft with precision vertical and horizontal navigation guidance information during approach and landing. With a growing emphasis on performance-based operations, different levels of operation may be authorized based on the flight equipment of a specific operator, and the ground equipment available at specific runways. While certain ground facility requirements are needed to support all levels of operations, a higher category of operations may be performed on different types of ground equipment if the airborne equipment, crew training, or other factors offset any changes in ground facility requirements. In these situations, operations are predicated on the use of specific equipment and/or procedures, which will require a specific approval. Additionally, the recent development of advanced displays, advanced guidance, vision systems, and hybrid systems have enabled a reduction of flight technical error (FTE) during approach operations. The reduction in FTE combined with a guided transition to the visual segment has led several states to develop, publish, and authorize IAPs with a 150 foot DH. 2.2 The FAA began publishing Special Authorization Category (SA CAT) I ILS approaches in 2010. The operational criteria are detailed in FAA Order 8400.13D. This order authorizes Category I ILS approaches with a DH as low as 150 feet (using radio altimeter minima) and a visibility as low as RVR 450 m (1400 ft) at runways with reduced lighting (compared to standard Category II requirements). Only operators authorized for Category II operations using aeroplanes operationally approved for at least Category II operations and equipped with an operable HUD approved for at least Category II operations are eligible for this operation. A specific approval is required and the HUD must be operated in the mode used for Category II or III operations and used to the DH. SA CAT I ILS approach minimums to 150 feet make no changes in pilot/controller terminology, procedures, or pilot procedures, and require no new ground equipment, airborne equipment, or certifications at suitably equipped runways. It leverages the use of advanced avionics and flight guidance systems that are already in many aeroplanes today to get lower minimums on more runways. Additionally, the SA CAT I ILS uses the advanced avionics and flight guidance systems to mitigate some of the runway lighting and ancillary equipment that is normally required for low visibility operations. Specifically, centerline and touchdown zone lights are not required for SA CAT I operations. There was substantial testing done to demonstrate that this operation can be done safely without these lights. This movement to a cockpit centric operation provides significant cost savings for aerodromes and opens up the possibility of many more runways for low visibility operations. Figure 1 depicts a profile view of a typical Special Authorization CAT I ILS operation. The flight crew s visibility cone at 1400 RVR from an aircraft with a minimum 17 cockpit downward view angle is shown in yellow. As the drawing shows, at 150 feet DH with RVR 450 m (1400 ft.) the aircraft will have flown over the first 600 feet of a MALSR with the crew able to see approximately an 800 feet segment of the approach lights. Calculation also shows that the crew will be able to use the approach lights for runway alignment until approximately 210 feet from the threshold at an altitude of 65 feet, when the approach lights will no longer be visible. This approach procedure currently requires the use of HUD to DH. 2
Figure 1 Cockpit Visibility at 150 foot Decision Height 2.3 There are many benefits derived from a new 150 foot DH. Expanding capacity; increasing flexibility in the terminal environment; minimizing the impact of weather and other disruptions; reducing transit time; and increasing predictability (decreasing domestic curb-to-curb transit time) are all identified as key goals and objectives in planning future air operations. A 150 foot minimum contributes to meeting each of these objectives by making additional runways available during periods of reduced visibility. Having more approaches available with the lower authorized minimums of RVR 450 m (1400 ft.) means fewer flights will divert. Flights that divert will have shorter distances to fly to a diversionary airport. Fewer diversions and shorter routings will result in reducing the workload and minimizing the impact of weather disruptions to the airspace system. Diversions to airports nearer the planned destination means reduced fuel cost, reduced passenger inconvenience and faster return to scheduled operations. Lower minimums will have no effect on determination of suitable alternate airports for flight planning purposes. However, it will increase the number and proximity of suitable diversionary airports for aircraft that need to divert due to weather conditions or mechanical problems while airborne. For example, an aircraft en route from Washington Dulles to New York City s La Guardia airport may be able to divert to Islip, NY instead of the filed alternate of Boston, MA, since Islip will be able to accept arrivals down to RVR 450 m (1400 ft.) instead of RVR 550 m (1800 ft.). 2.4 With the success of the FAA SA CAT I ILS and the many benefits to a 150 ft. DH, the AWOH ARC is proposing establishing total system performance based criteria for operations down to 150 ft. DH. There have been numerous advances in both the navigational systems (ground and satellite based) and the aircraft avionics since the establishment of 200 ft. DH. The total system error (TSE) is much reduced compared to the ILS of the 1960 s. Simply put, these advances can consistently deliver the aeroplane to DH in a much tighter window than ever before. An example of a new technology that could meet the performance based criteria for operations down to a 150 ft. DH is Synthetic Vision Guidance System or SVGS. RTCA SC-213 has recently published Minimum Aviation Performance Specifications for a Synthetic Vision Guidance System (SVGS), DO-XXX. SVGS as defined in this MASPS is a new airborne guidance system designed to enable operations to a Decision Height as low as 150 ft. height above touchdown. SVGS is a combination of flight guidance display technology and high precision position assurance monitors. The SVGS flight instrument display provides a continuous, geo-spatially correct depiction of the external scene topography, including obstacles, augmented by the display of the runway of intended landing. The SVGS display may be implemented on a head down Primary Flight Display, and/or a Head- Up Display (HUD. SVGS includes additional symbology elements, integrity and performance monitors and 3
annunciations that support and enable low visibility operations. Additional flight instrument symbology and monitors to assure accurate rendering of the external scene are included. The additional systems and flight instrument display symbology, including an earth referenced flight path vector (FPV), flight path angle reference cue (FPARC) and Depiction of the Runway of Intended Landing (DRIL), provide enhanced control, and position and path awareness via a continuous, intuitive indication to the pilot of the aircraft trajectory relative to the touchdown zone. The additional airborne monitoring ensures the same level of accuracy, availability and integrity as the equivalent ground based systems normally used for these operations. The SVGS provides the pilot with a dynamic perception of position, trend, and motion, which facilitate the pilot s transition to the use of visual references out-the-window (OTW). The interpretation of this spatial context, i.e., interpretation of present and future position with respect to runway of intended landing, by the pilot, allows for improved flight technical error performance and reduced cognitive workload. The SVGS may be implemented on a Head-Down Display (HDD) or a Head-Up Display (HUD). However, when SVGS is implemented on a HUD, the SVGS must also be displayed on the pilot monitoring display to support crew coordination, and also be available to the primary flight display of the pilot flying in the event of failure of the HUD. The development of SVGS brings increased importance toward developing an ICAO standard for 3D Type B approach operations to 150 feet. 2.5 In summary, the AWOHARC has three recommendations for the development of published IAPs with 150 foot DH. First, coordinate with the IFPP to verify that current PANS-OPS criteria are suitable for IAPs with 150 foot DH if based on radio altimeters. Second, develop the performance based conditions required to obtain a specific approval for SA CAT I operations to a 150 foot DH. Third, work with the IFPP to develop criteria for charting these new procedures. 3. ACTION BY THE MEETING 3.1 The FLTOPSP/1 is invited to: a) Note and review the contents of this working paper; b) Agree, as may be amended, the actions listed in paragraph Attachments 1. Sample U.S. FAA Special Authorization CAT I ILS Instrument Approach Procedure 4
Attachment 1