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Candidate Operator Data Items For Trajectory Modeling

Candidate Operator Data Items For Trajectory Modeling. Dan Kirk, Ph.D. Stéphane Mondoloni, Ph.D . October 10, 2012. Overview (1 of 2). Operator-provided data includes that obtained from a flight operations center, and directly from the flight deck

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Candidate Operator Data Items For Trajectory Modeling

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  1. Candidate Operator Data Items For Trajectory Modeling Dan Kirk, Ph.D. StéphaneMondoloni, Ph.D. October 10, 2012

  2. Overview (1 of 2) • Operator-provided data includes that obtained from a flight operations center, and directly from the flight deck • Need to assess rough benefits (increased accuracy) vs. cost • Where possible, consider alternatives to a flight deck downlink due to equipage and transmission costs • Goal is to first produce a list of candidates, then narrow-down based on cost/benefits • Classify operator data into path-independent vs. dependent data

  3. Overview (2 of 2) • Path-independent data; tailored parameters for • Vertical/Speed modeling, e.g., thrust and drag • Lateral modeling • Path-dependent Data • SC-214 ADS-C Extended Projected Profile (EPP) • Vertical, speed and lateral waypoint data • ARINC 702A-3 FMS trajectory data • Provision of turn data • ARINC 424 Path/Terminator data • Operational performance limits • Planned FMS Hold data

  4. Path-Independent Data • Subcategories; aircraft-specific data for • Vertical/Speed modeling of • Thrust, Drag and Weight • Speed modeling on interim level-offs • Lateral modeling • Bank angle, FMS handing of parallel offsets • Data access alternatives include • Database lookup with aircraft registration • Direct provision from the Operator

  5. Path-Independent DataVertical/Speed Modeling - Thrust • Engine variant • Variation of engine models on a given airframe can lead to significant differences in climb performance • Application of climb de-rating • Used to reduce in-service deterioration • Applied to maximum climb thrust, e.g., • Applied as a fixed % reduction below a given altitude (such as 10,000 ft); gradually reduced to 0% within a higher altitude band • Anti-icing impact on thrust • Additional thrust required on descent • Air bleed reduces the maximum thrust available

  6. Path-Independent DataVertical/Speed Modeling – Drag & Weight • Drag multiplier - Deviation from a base drag profile • The addition of winglets to an older airframe will likely reduce the drag profile • Increased drag, e.g., due to • Addition of antennae • Operation due to a different Center of Gravity location • Weight • Takeoff weight • Engine variant to improve fuel burn estimates • (Operator-provided along-path weight estimates covered in path-dependent data)

  7. Path-Independent DataSpeed Modeling on Interim Level-Offs • Need to improve prediction of the airspeed on an interim level-off before it is assigned • Speeds likely dependent on the anticipated time of the level-off, e.g., on climbs • Maintain climb thrust (and thus accelerate) if a short level segment • Throttle-back and maintain airspeed if a longer segment • Need to either • Establish guidelines for speeds on level-off, or • Identify alternatives/parameters for operator selection

  8. Path-Independent DataLateral Modeling • Bank Angle Limit • Function of airspace type or altitude • Alternative to the transmission of turn radius for each turn • Roll-in and roll-out rates (or lead/lag times in turn initiation/completion) if modeled • Parallel offset maneuvers; FMS differences including • Initial and rejoin turn size (e.g., 300) • Ability to enter a route rejoin fix into the FMS • Offset termination at the start of a STAR

  9. Path Dependent DataSC-214 ADS-C Extended Projected Profile • For up to 128 waypoints, position (latitude/longitude) and (as available): • Fix name, Altitude, Estimated ETA, Airspeed • Vertical Type (e.g., Top of Descent, Top of Climb) • Lateral Type (e.g., Offset Start, Overfly) • Altitude constraints (At, At or Above, At or Below, Window) • RTA (Time, Optional: Achievable, Not Achievable) • Speed restriction value • The Extended Projected Profile (EPP) can also contain • Gross mass, gross mass at top-of-descent • Speed schedule, min/max speed schedule • Trajectory intent status, crossover level ____________________ Source: Data Communications Safety and Performance Requirements, PU-10, Version J – Converged SPR, 22 June 2012

  10. Path Dependent DataEPP Waypoint Vertical Types • Top of climb • Top of descent • Start of step-climb • End of step-climb • Start of step-descent • End of step-descent • Start of cruise climb segment • End of cruise climb segment • Level off • Start of descent • Start of climb • Constant Mach segment • Speed change • >10 K IAS or 0.10 Mach • Speed limit • Altitude–based speed limit or restriction (e.g., 250 knots at 10,000 ft)

  11. Path Dependent DataEPP Speed, Min/Max Speed Schedules • Speed Schedule • Climb airspeed(Indicated and/or Mach) • Initial cruise airspeed at Top of Climb • Last cruise airspeed at Top of Descent • Descent airspeed • Min/Max Speed Schedule (used by the ground system to compute min/max ETAs1) • Min/Max Climb airspeed (Indicated and/or Mach) • Min/Max Initial cruise airspeed at Top of Climb • Min/Max Last cruise airspeed at Top of Descent • Min/Max Descent airspeed ____________________ 1. It is assumed the ETA range will be buffered by the ground system to generally avoid cases where the ETA cannot be met, e.g., due to unexpected headwinds

  12. Path Dependent DataEPP Waypoint Lateral Types

  13. Path Dependent DataEPP Trajectory Intent Status • Aircraft coupled/not coupled with FMS specified lateral flight plan • Aircraft coupled/not coupled with FMS specified vertical flight plan • Aircraft coupled/not coupled with FMS specified speed flight plan • Date and time of last meteorological model update (if available)

  14. Path Dependent DataAdditional ARINC 702A-3 Data • ARINC 702A-3 (Advanced Flight Management System) provides a Trajectory Intent Format • Supports multiple flight plan types, e.g., • Active, Secondary, Data Link, Modified/Temporary • Ability to support multiple types expected to be important in any trajectory negotiation • Active trajectory should reflect the current clearance • Non-active trajectories support automated trajectory negotiation • Also provides • Additional waypoint information and labels • Barometric pressure at climb/descent transition altitudes

  15. Path Dependent DataAdditional 702A-3 Waypoint Data • Additional (not in EPP) waypoint data items are • Geometry: Start point, Line to point, Arc to point • Path RNP • Wind speed, direction • Turn radius, turn center latitude/longitude • Barometric correction flag • Additional waypoint labels; waypoint is • The aircraft projection onto the route • Non-flyable; Point of discontinuity; Runway • On current or next leg • Turn points on holds presumably modeled, but no labels provided

  16. Path Dependent DataProvision of Turn Data • 702A-3 provides turn radius and center position • These are not provided in the ADS-C EPP (or the CPDLC Route Clearance) • This data could typically be derived from • Operator-provided bank angle limits (if accurate), or • Published route, e.g., RF turn or DME Arc • However, the turn start/center is ambiguous for turns cleared to start “now” (without a specified start position) • Only needed for the initial turn on a new clearance; could be covered under short-term intent data

  17. Path Dependent DataOperator Provision of ARINC 424 Data (1 of 2) • Not all trajectory segment legs will be flown with equal accuracy • Depends on how the path will be navigated • Can be flown as a track (most accurate) • Course (to NAVAID), or • Heading (least accurate) • Depends on how the leg will be terminated, e.g., • Fix (most accurate) • Intercept radial, or • A target altitude is reached (least accurate, depends on the aircraft’s actual altitude rate)

  18. Path Dependent DataOperator Provision of ARINC 424 Data (2 of 2) • ARINC 424 defines the allowable Path/Terminator (P/T) combinations • Used in coding the SID/STAR and Approach Procedure definitions • When not flying one of these procedures • Operator-provided P/T data (from the FMS) would assist in estimating the lateral navigation state and uncertainty, e.g., • En route aircraft is flying a track vs. course, or • Aircraft has been cleared direct to a fix following a heading • Is now established on a DF (Direct to Fix) leg

  19. Path-Dependent DataOperational Performance Limits (1 of 2) • Reflect limits applied by the operator • Particularly needed for Trial Plan modeling • Avoid ground automation-generated plans that are rejected due to limit violation • Min/Max operational speed limits could be similar to the EPP Min/Max Speed Schedule • Min/Max Climb airspeed limits (Indicated, Mach) • Min/Max Initial cruise airspeed limit at Top of Climb • Min/Max Last cruise airspeed limit at Top of Descent • Min/Max Descent airspeed limits (Indicated, Mach)

  20. Path-Dependent DataOperational Performance Limits (2 of 2) • Also need • Operational min/max climb and descent rates • Maximum altitude • These could be specified for selected waypoints to reflect • Dependence of the rate ranges on altitude and (for long flights) flight duration • Need for maximum altitude only on the cruise portion and (for long flights) flight duration

  21. Path Dependent DataPlanned FMS Hold Data • No planned hold information is explicitly represented in the ARINC 702A-3 Intent trajectory • Planned FMS Hold information could be useful to the ground automation, e.g., • In planning hold release times • Will the aircraft be able to exit the hold at the slot time that is now available? • Free up airspace by reducing the required holding pattern size • Trajectory information could include • Planned holding speeds pattern size and speeds • Planned time(s) at the holding fix

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