Australian Progress Brief

1. Australian Progress Brief Trajectory Prediction Down-Under Greg McDonald Senior Operational Specialist

2. Airservices Australian Progress Brief Trajectory Activities Where we come from What we have found Where we see the use

3. Best system in the world, however… Can it cope with this? Maybe.. Can it efficiently cope with this?

4. Trajectory Based Operations TBO ICAO GATMOC EUROCONTROL SESAR FAA NextGen Australian AATMSP UPR PLAN CDA RNP CDM SWIM ATFM RNP-AR RNP-AR FPCF CTMS AMAN SEPARATE DMAN ALOFT MAESTRO EFFICIENT ? FIXM TAAATS FDP AFS TRAJECTORY PREDICTION

5. Tailored Arrivals (A Brief History) • A Boeing project to resolve limited FMS memory • Initial trials demonstrated arrival path could be uplinked • In Australia there is little difference to voice issued linked STAR • We have been concentrating on prediction aspects of Tailored Arrivals. • US locations have been concentrating on the move to static paths uplinked to the arriving aircraft. • FAA recently announced Tailored Arrivals would migrate to “Fully Operational Status” • LVNL of Netherlands testing a prototype tool SARA (Speed And Route Advisor)

6. TOD 3353S 14401E MINAT 3403S 14321E 290Kts 18000B VIGRA 2225 2237 HOLLY 280Kts 2243 15000A • Alternate RNAV Routes for: • Path Stretching 2247 STIPE 2252 • Path Shortening LEKMA 250Kts 3000 2255 2257 Components include – Dynamic variation of waypoint positions and route segments… The Classic Tailored Arrival

8. ML RWY 27 Arrivals • Current operations • 732 movements shown • Maestro sequencing to 30NM Feeder Fix • Runway linked STARS • FDP based trajectory prediction • ATC fine tuning required • Large percentage of aircraft untouched • Similar results for all runways • A good location to study

9. What if we could • Allow aircraft to continue to fly STD speed and profile, conduct a CDA and not impact on efficiency? • To do this we would need to: • Know what the FMS was thinking • Have a confidence in the trajectory prediction including aircraft derived information?

10. FANS How can we extract trajectory predictions made by the FMS using current day technology? • Implemented in most wide body aircraft since early 90’s • CPDLC • ADS-C • Position report • Observed weather • Predicted Route Group • Fixed Projected Intent • Intermediate Projected Intent

11. Intermediate Projected Intent (IPI) Trajectory Change Points (TCP). Set of maximum 10 Only TCPs in IPI that are within a specified look-ahead-time  Fixed Projected Intent (FPI). TCP: Bearing and distance (converted to lat/lon) Altitude Time Remaining IPI becomes visible as aircraft progresses. Current Position Intermediate Projected Intent Fixed Projected Intent Remaining IPI Longitudinal AIRCRAFT TRAJECTORY Horizontal Look-ahead-time Tmax FPL Track FPL Track Look-ahead-time Tmax FPL Track

12. Ground Based Air Based Trajectory Prediction • Ground Based • Has complete forecast • ATC intent • Missing aircraft intent • Unclear aircraft performance • Air Based • Actual weather • Actual aircraft performance model • Limited forecast • Unaware of ATC intent or Combination?

13. Trajectory Prediction Process

14. Airborne (FMS) Input Ground (TAAATS) GROUND AIR Differences between FMS and TAAATS TP Derived from GPS/IRS and baro. altitude, all relevant conditions known (e.g. weight). Initial Conditions Surveillance. Not all relevant conditions known (e.g. weight). Detailed model of aerodynamic and thrust coefficients to evaluate equations of motion to derive A/C performance (kinetic model). Aircraft Performance Model A/C performance is defined by static performance tables (static solution of equations of motion; kinematic model). Limited weather forecast (QNH, enroute winds, climb/descent winds and temperature). Benefit of sensing current winds/temp. Environmental Model Extensive weather forecast (area forecast, multiple levels). Kinetic. Trajectory Engine Kinematic. FMS knows exactly how it is going to operate the aircraft to fulfil the flight plan taking into account any imposed (procedural) constraints by ATC (when input by crew). Aircraft Intent Limited view of what aircraft is going to do. ATS Flight Plan provides info on lateral path, cruise level and cruise speed. TAAATS is not aware of A/C intended climb and descent performance (static performance tables)

15. What if we combine best of both worlds? • A kinetic model on the ground deriving aircraft performance from BADA aerodynamic and thrust models, • Using extensive weather forecast on ground enhanced with actual data from aircraft, and • Synchronise Aircraft Intent between ground and air.

16. It will take years before aircraft intent can be exchanged between ground and air. Back to today… Is there a way to demonstrate the benefits of using AIDL in a ground based TP? AIDL?

17. ASIS Project

18. ASIS Results As shown the deviations of the flown distances can be reduced by a factor of 10 (from ~2% to about ~0.2%) using AI information from the FMS via AIDL.

19. BADA AIP DATA Flight Plan How to fill the blanks? Where to get the Aircraft Intent? Longitudinal HA TOD TOC START STAR END SID AIRCRAFT INTENT AIRCRAFT TRAJECTORY COA COA ? ? Horizontal Speed Profile TLP TLP TLP TLP TLP TLP TLP TLP HS(MACH) HS(MACH) HS(MACH) HS(CAS) TLP HS(CAS) HS(CAS) HS(CAS) HS(CAS) TL(LIDL) TL(CMB) TL(CMB) HA TL(LIDL) TL(LIDL) TL(LIDL) HS(CAS) TL(LIDL) TL(MTKF) HS(MACH) TLP HS(CAS) HS(CAS) TLP TLP TLP TLP TLP TLP TLP TLP TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) TL(CMB) TL(CMB) TL(TKF) TL(LIDL) Vertical Profile Propulsive Profile Lateral Profile Consider a typical operation modelled in AIDL (simplified)… Constant CAS descent Constant Mach descent Constant Mach climb Take Off Approach and landing 250KCAS in TMA Cruise Constant CAS climb Flap deployment ? ? ? ? ? ? ? ?

20. What about FANS? We can make assumptions to fill the blanks: “Aircraft climbs at 280KCAS and crosses over into flight-planned cruise Mach number. Descent is initiated at flight-planned cruise Mach number into 280KCAS”. “ Flap deployment is started at 230KCAS, and approach speed is 180KCAS”. “Aircraft weight is...” Etc… Better than using kinematic performance tables as TAAATS FDP is currently doing, but still does not allow for flexibility of operation… Is there a way to get some of the blank fields from the aircraft using current available technology? For example get the actual descent target CAS instead of a assumed 280kts?

21. Airline Proce-dures FANS Longitudinal HA TOC TOD START STAR END SID AIRCRAFT INTENT AIRCRAFT TRAJECTORY COA COA Horizontal Speed Profile TLP TLP TLP TLP TLP TLP TLP TLP HS(CAS) HS(MACH) TLP HS(MACH) HS(CAS) HS(MACH) HS(CAS) HS(CAS) HS(CAS) TL(LIDL) HS(CAS) TL(CMB) HA TL(LIDL) TL(CMB) TL(LIDL) TL(LIDL) TL(LIDL) TL(MTKF) TLP TLP TLP HS(MACH) HS(CAS) TLP TLP TLP TLP TLP HS(CAS) HS(CAS) HS(CAS) HS(CAS) HS(CAS) HS(MACH) HS(MACH) TLP TL(LIDL) TL(TKF) TL(CMB) TL(CMB) TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) Vertical Profile Propulsive Profile Lateral Profile Consider a typical operation modelled in AIDL (simplified)… This will work, but have we modelled the descent correctly?

22. Can we synchronise the descent path and use a hold path approach instead? A main focus in TBO is improved predictions for the metering fix and runway; hence improved predictions for the descent trajectory are required. Most TPs compute the descent path by backwards integrating the aircraft’s target performance (e.g. target descent speed) until cruise level is reached (hold speed approach/ VNAV-SPD), like example previous slide. Even with synchronised Aircraft Intent between ground and air, differences in the Environmental Model will lead to different descent paths.

23. HPA HPA HPA HPA HPA HA HA AIRCRAFT INTENT AIRCRAFT INTENT VNAV-SPD Speed Profile Speed Profile TLP HS(CAS) TLP TLP TLP TLP HS(CAS) TLP TLP HS(MACH) TLP HS(MACH) HS(CAS) TLP HS(CAS) HS(CAS) HS(MACH) HS(CAS) HS(CAS) HS(MACH) TLP HS(CAS) TLP TLP TLP HS(MACH) TLP TLP TLP TLP TLP TL(CMB) TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) TL(TKF) TL(TKF) TL(CMB) TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) TL(LIDL) TL(CMB) TL(CMB) What if we model the behaviour? Vertical Profile Vertical Profile VNAV-PTH Propulsive Profile Propulsive Profile Lateral Profile Lateral Profile The flexibility of AIDL allows to model a VNAV-PTH descent instead. VNAV-SPD: Hold speed VNAV-PTH: Hold (geometric) path Altitude free variable How does that affect the prediction? Speed free variable

24. Allowable region for speed to vary HPA HPA HPA AIRCRAFT INTENT Metering Fix Speed Profile HS(CAS) TLP TLP TL(LIDL) TL(LIDL) Vertical Profile Propulsive Profile Lateral Profile The airspeed keeps fluctuating, however within the buffer. The resulting ETA for the final point is obtained from the variable speed instead of target descent speed and is more representative of the reality. The aircraft speeds up again and thrust is set back to idle. The AIDL changes from TL(IDLE) to HS(CAS); i.e. thrust is the free variable while speed and path are fixed. Target speed on descent; reverse engineered from FANS. Graph that displays CAS and thrust versus altitude. While in VNAV-PTH, the speed on descent is allowed to vary form the target speed within a specified buffer. The airspeed reaches lower boundary of buffer. Throttle is required to maintain path and the lower-buffer-speed. More pitch up is required to maintain the geometric path, as result the aircraft slows down further. Airspeed varies as experienced winds are different to forecast (geometric path inaccuracies). Point mass model to be integrated along geometric path. Suppose we need an ETA for the metering fix Geometric path created from FANS Trajectory Change Points. Speed free variable!! Speed fixed Speed free variable!! Altitude (path) fixed Thrust fixed Thrust free variable!! Thrust fixed

25. Results Results • Same 413 flights • Bias in data disappeared • 58% reduction in std w.r.t. EUROCAT • 13% reduction in std w.r.t. FMS(!)

26. Thoughts? • All ground systems require some trajectory prediction capability in order to sequence effectively - even for an RTA solution. • This is how we have achieved accuracy in trajectory prediction, other systems may do it differently and to different requirements but the same basic elements are used. • It is not simply about the trajectory but the specific aircraft intent for the flight. • What are the performance parameters or objectives for that specific flight • How best to model “what if” options on the ground for that flight. • FIXM has to carry information to enable each system to build a synchronised trajectory from intent and meeting local accuracy requirements. • AIDL has proven to be an effective method to describe intent.

27. Questions?

29. The Aircraft Intent Description Language (AIDL) • Two levels in the language grammar: lexical and syntactical • Lexical Level: Instructions • Instructions are atomic inputs to the Trajectory Engine that capture basic commands and guidance modes at the disposal of the pilot/FMS to direct the operation of the aircraft • Syntactical level: Operations • Operations are sets of compatible instructions that, when simultaneously active, univocally determine the ensuing aircraft motion • With a reduced set of instructions (AIDL alphabet), any possible aircraft operation can be formally specified in such a way that the ensuing aircraft motion is unambiguously determined

30. AIDL elements Lexical Rules Lateral Instructions Syntactical Rules Vertical Instructions Speed Instructions Propulsive Instructions Configuration Instructions (7) (3) (8) (7) (4) (4) (9) AIDL Grammar (10 Rules) Alphabet (32 Instructions) 1. An operation must contain three non yellow instructions of different color 2. An operation can contain as much yellow instructions as configuration elements are modeled 3. One instruction must be green

31. Example 1: Climb at constant CAS ? ? ? ? ? ? Instructions Attributes Aircraft Intent Instructions Speed Instructions • Speed: CAS • Law: Constant • Value: 280 Knots Vertical Instructions • Throttle: Maximum Climb • Law: Engine Regime • Value: Given by the APM Throttle Instructions Lateral Instructions • Lateral: Aircraft bearing • Law: Constant • Value: 175º Configuration Instructions • Clean Configuration (e.g. high lift devices, landing gear and speed brakes)

32. Example 2: Economy Cruise ? ? ? ? ? ? Instructions Attributes Aircraft Intent Instructions Speed Instructions • Speed: Mach • Law: Economy • Value: Given by the economy law Vertical Instructions • Vertical: Altitude • Law: Constant • Value: 33000 ft Throttle Instructions Lateral Instructions • Lateral: Track • Law: Great Circle • Value: Given by the law Configuration Instructions • Clean Configuration (e.g. high lift devices, landing gear and speed brakes)

33. Example 3: Descent with a constant radius turn ? ? ? ? ? ? Instructions Attributes Aircraft Intent Instructions Speed Instructions • Vertical: Path angle • Law: Constant • Value: 3º Vertical Instructions • Throttle: Idle • Law: Engine Regime • Value: Given by the APM Throttle Instructions Lateral Instructions • Lateral: Track • Law: Circular Arc • Value: Given by the law Configuration Instructions • Clean Configuration (e.g. high lift devices, landing gear and speed brakes)

34. HS HS HS HS HS HS HS Longitudinal HA HA TL HA HA AIRCRAFT INTENT AIRCRAFT TRAJECTORY Horizontal SBA HBA SBA OPERATIONS OP#3 OP#5 OP#6 OP#7 OP#8 OP#9 OP#10 OP#11 HS HA TL ST TL TL TL TL TL TL THP THP THP THP THP THP THP THP OP#1 OP#2 OP#4 Time Example: i) Combining Aircraft Intent Instructions FL320 TOD TA M .88 M .78 280 KCAS 4500ft 180 KCAS N370945.72 W0032438.01 R? 110 075 Speed Profile Vertical Profile Propulsive Profile Lateral Profile

35. Capture Speed CAS=180 kt Capture DES CAS CAS=280 kt Capture altitude h=4500 ft Capture DES Mach M=0.78 HS HS HS HS HS HS HS HS HA TL HA HA HA HA HA AIRCRAFT INTENT Pilot event Roll-in anticipation End of engine transient to IDLE Capture of target bank Roll-out anticipation Capture of great circle ? ? ? d d d d SBA HBA SBA OPERATIONS OP#3 OP#5 OP#6 OP#7 OP#8 OP#9 OP#10 OP#11 HS HA TL TL TL TL TL TL ST TL TL THP THP THP THP THP THP THP THP THP THP Fixed Floating Auto OP#1 OP#2 OP#4 Example: ii) Defining Instructions’ Execution Intervals Speed Profile Altitude Profile Propulsive Profile Lateral Profile Trigger Condition Explicit Implicit Default LinkedL

36. HS HS HS HS HA HA AIRCRAFT INTENT d ? ? d d SBA HBA SBA OPERATIONS OP#3 OP#5 OP#6 OP#7 OP#8 OP#9 OP#10 OP#11 ST TL THP THP OP#1 OP#2 OP#4 Example: iii) Providing Instruction Parameters Speed Profile Altitude Profile Propulsive Profile Lateral Profile Parameter Scalar Object Auto Fixed Default

37. Potential Benefits of using the AIDL Determines a unique trajectory (no ambiguity) Determines the trajectory before hand without the need to compute or execute it (abstraction) Guarantees feasibility (flyability) of the described trajectory (correctness by construction) Determines the trajectory at any point (continuity) Represents any possible aircraft motion that makes sense operationally (realism) Admits arbitrary level of detail in the definition of the aircraft motion (scalability) Independent from the varying atmospheric conditions (invariance to atmospheric conditions) Independent from the specific aircraft model (invariance to aircraft performance) Conveys any operationally relevant aspect of the trajectory (completeness) Information involved is necessary and sufficient (reduced bandwidth requirements) Readily understandable by humans (intuitiveness) Natural trajectory encryption (security)