Michael Cramer

Estimated Time Of Arrival (ETA) performance system comparative evaluation

As the United States (U.S.) moves toward the various phases of Next Generation Air Transportation System (NextGen), there will be more emphasis on control of aircraft using time as well as the traditional speed control. With this in mind, Radio Technical Commission for Aeronautics (RTCA) was directed by Federal Aviation Administration (FAA) in 2012 to revisit the Minimum Aviation System Performance Standards (MASPS): Required Navigation Performance (RNP) for Area Navigation (RNAV), DO-236B [1], to update the requirements for RNP RNAV systems based on lessons learned from implementing Performance Based Navigation (PBN). The committee was also asked to consider a forward look/refinement of the time-based requirements for systems. The RNP RNAV system performance standard DO-236C [2] Change 1 [3] amended existing standards from DO-236B by expanding the minimum requirement for system computed Estimated Time of Arrival (ETA) in a Flight Management System (FMS). The new minimum functional requirement is that the ETA must be available for each fix in a flight plan; the previous minimum only required ETA at the “go to” fix. In an important addition, DO-236C Change 1 sets a minimum performance requirement on ETAs at all planned (future) fixes in the onboard flight profile. Thus the standard has been expanded both in the functional and the performance requirements for ETA in an RNP RNAV system.

Use of magnetic variation and station declination for heading (VX) and course (CX) leg types

Leg types, also known as path terminators, are used in aircraft navigation to define paths as routes for RNAV equipped aircraft. Many leg types are specifically defined to cause the Area Navigation (RNAV) system to emulate the actions that an aircrew would take when flying the route manually based on the text and other depictions on the chart. Some emulate magnetic headings or courses, which, for various reasons, can lead to differences between what the procedure designer intended and what the RNAV system displays or flies. Two in particular are in common use individually and in combination, and this paper will explore the potential for unexpected differences in the resulting paths. These two are the heading type (Vx) which may be used where the procedure or airspace designer calls for a heading to some type of termination, and the Course type (Cx) which may be used where designers wish to fix the aircraft path over the ground using a course defined by a navigational aid (NAVAID). Issues arise because of the need to implement magnetic courses and headings in an RNAV system that navigates in a true north reference frame. Given that the Earths magnetic field orientation varies with location on the Earth (hence true north and magnetic north change relative to each other), changes with time, and that NAVAIDS and runways are marked/oriented in the magnetic reference frame of the time they are surveyed, care must be taken to make the RNAV system emulate the procedure intent; this paper will describe and summarize those cautions and issues.

Collection and analysis of 4D intent downlink data from operational flights

Continental Airlines and The MITRE Corporation have collaborated in an effort to collect and analyze intent data from operational flights in the U.S. National Airspace System (NAS). Flight intent in four dimensions (4D) which provides latitude, longitude, altitude and time (among other information) is being provided by Continental Airlines from Boeing 737–800 series aircraft equipped with GE Aviation Flight Management System (FMS) avionics.

Flight management computer (FMC) field observations trials: Standard instrument departure with Radius-to-Fix (RF) path terminators

• 2004 — Assessment of Operational Differences Among Flight Management Systems • 2005 — Analysis of Advanced Flight Management Systems (FMSs • 2006 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Lateral Path • 2007 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Vertical Path • 2008 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Radius-to-Fix Path Terminators • 2009 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Lateral and Vertical Path Integration • 2010 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Standard Instrument Departures • 2011 — Analysis of Flight Management Systems (FMSs), FMC Field Observations Trial, Area Navigation (RNAV) Holding