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OPA

VIEWS: 10 PAGES: 17

									       OPA

WG78/SC214 SG-meeting
   24-28 Oct 2011


                        1
         CPDLC Operational Transaction
                                                   ATSU                ACSP              AIRCRAFT


                                           Controller     ATSU        Comm.           Aircraft
                                                          System      service         System     Flight crew



                     Composition
                                                                    Initiating
                                                                    message


       Initiator                       Reaction:
 RCP               TRN                 Responder
                            RCTP




                                                                   Closure Response
                         Recognition




• RCP : E-t-E performance in support of an ATS function
• TRN : Pseudo E-t-E and monitoring purposes
• RCTP: Technical systems (AC, ATSU, ACSP) for data communication
• Initiator : Msg composition and recognition, including HMI manipulations                  2
• Reaction : Thinking time and response composition of Responder, including HMI manipulations
                              Core Principles
1.   Realistic times for RCTP
     –   ENR-2 allows larger times than CONT
     –   Current ‘78/214’ draft considers RCTP Specs for RCP120 as lowest common denominator for
         future Continental RCP specs:
     –   Worst case msg = Route Clearance ~15 Waypoints Msg size = 2Kbyte

2.   Realistic Human Response times
     –   Complex UM requires more FC time than simple UM
     –   WILCO response is a truly closure response and includes the time the pilot has evaluated and
         is able to complete the instruction.
     –   STANDBY is an Interim response Does not count for transaction closure.

3.   ATSU & AC Delays
     Idea is to have same delay values for Aircraft, independent from RCP Spec
     –   AC value in RCP240/400 (OCR) =10s (95%). AC value for RCP120/300 (CONT) =7s (95%).
     –   AC value will become 10s as common value With equal E-t-E, Responder becomes slightly
         less for CONT RCPs.

4.   Common approach for timing allocations
     –   Based on Exponential Statistical distribution
     –   Requires change of RCP240 and RCP400 Spec Is this acceptable?




                                                                                                    3
  RCP Specs in ENR-1, TMA, APT
Core principles from slide 2 has led to
• RCP120: ATC Comm-simple/VCM
   – Certainty that perf is correct: Systems (VDLM2-M) are designed
     to meet it.
• RCP300: DCL and 4DTRAD
      • Complex CPDLC msg Operations
      • Uncertain they are correct
          – FAA/DCL – simulations are ongoing
          – Need to wait for 4DTRAD validation


• Observed that RCP assignments in Updated ATS
  functions section for DCL & 4DTRAD do not match

                                                                      4
            Current draft SPR timings:
    ENR-1, TMA, APT, using VDLM2-M
            RCP communication Transaction Time and Continuity

RCP Type                    RCP120                       RCP 300
Transaction Time             ET (sec)       TT (sec)      ET (sec)        TT (sec)
Parameter                    C=99.9%        C=95%         C=99.9%         C=95%
Transaction Time                120             57           300             136
                              RCP Time Allocations
Initiator                       30              13            30             13
TRN                             100             48           280             126
                              TRN Time Allocations
Responder                       92              40           272             118
RCTP                            27              15            27             15
                                                                                         Need to
                                 RCTP Allocations                                        become
ATSU                            14              6             14              6          10s
                                                                                         99.9% value
ACSP                            18              8             18              8          to be
Aircraft                        16              7             16              7          changed
                                        Notes
                                                                                              5
Note 1: The bolded values represent the constraining points in the assumed statistical
distribution, the remaining points are allocated to fit the assumed distribution.
First Perf findings: FAA-DCL Sim Current
  draft against RCP300 (1), using POA
             RCP communication Transaction Time and Continuity

 RCP Type                  Simple     Complex     RCP300         RCP400
                          DCL SIM     DCL SIM
                                                                            Fits into SIM
 Transaction Time         TT (sec)    TT (sec)    TT (sec)       TT (sec)
 Parameter                C=95%       C=95%       C=95%          C=95%
                                                                            results
 Transaction Time            ?           ?          136            182
                           RCP Time Allocations
 Initiator                   ?           ?           13            13
 TRN                         83         181         126            168
                           TRN Time Allocations
 Responder (Pilot)           67         156         118            156
 RCTP                        16          25          15            25
                             RCTP Allocations                               POA
 ATSU                         ?          ?           6              6       7s need to be
                                                                            changed
 ACSP                         ?          ?           8             19       ACSP slightly less
 Aircraft                     ?          ?           7              7
                                                                                       6
  First Perf findings: FAA-DCL Sim Current
    draft against RCP300 (2), using POA

• Pilot Response time for complex DCL clearance
  shows that RCP300 is not met
  – 181sec vs 136sec
• RCTP (POA) time for complex DCL clearance
  shows that specified RCTP is not met
  – 25sec vs 15 sec
  – Q: POA timing based on future AC traffic demands and
    high rate of AOC messages?
• RCP400 fits the DCL Sim results
                                                       7
         Impact POA on RCTP120
• Current SPR draft specifies RCTP(95%)=15s.
   – Based on practical experience (LINK2000+) and Ops approved
     products.
   – A/G-sub-network: VDLM2-multichannel (ATS + AOC traffic).
   – Current performance should drive the future data comms.
   – Wrong signal that future performance is worse than current performance

• Impact on POA based RCTP in En-Route
   – Evaluation not started by FAA:
       • POA  Larger RCTP (25s at 95%). It is known that POA perf can be worse
         than 25s.
       • AOA  RCTP TBD

• Consequences larger RCTP times:
   – For same E-t-E value, Responder time is compromised for large RCTP
     times
       • POA  Not used in EUR for DL-IR due to its unpredictable performance.
   – Usability of CPDLC service in dense ER degrades.
                                                                                  8
RCP120: Draft SPR vs RCTP POA=25s
               RCP communication Transaction Time and Continuity
   RCP Type                    RCP120                       RCP 120
   Transaction Time             ET (sec)       TT (sec)      ET (sec)        TT (sec)
   Parameter                    C=99.9%        C=95%         C=99.9%         C=95%
   Transaction Time                120             57           120             57
                                 RCP Time Allocations
   Initiator                       30              13            30             13
   TRN                             100             48           100             48
                                 TRN Time Allocations
   Responder                       92              40            81             35
   RCTP                            27              15            50             25
                                    RCTP Allocations
   ATSU                            14              6             14              6          POA
   ACSP                            18              8             44             19
   Aircraft                        16              7             16              7
                                           Notes
   Note 1: The bolded values represent the constraining points in the assumed statistical
   distribution, the remaining points are allocated to fit the assumed distribution.          9
RCP300: Draft SPR vs RCTP POA=25s
               RCP communication Transaction Time and Continuity

   RCP Type                    RCP300 (VDL2-M)              RCP 300 (POA)
   Transaction Time             ET (sec)       TT (sec)      ET (sec)        TT (sec)
   Parameter                    C=99.9%        C=95%         C=99.9%         C=95%
   Transaction Time                300             136          300             136
                                 RCP Time Allocations
   Initiator                       30              13            30             13
   TRN                             280             126          280             126
                                 TRN Time Allocations
   Responder                       272             118          267             116
   RCTP                            27              15            50             25
                                    RCTP Allocations
                                                                                            POA
   ATSU                            14              6             14              6
   ACSP                            18              8             44             19
   Aircraft                        16              7             16              7
                                           Notes
   Note 1: The bolded values represent the constraining points in the assumed statistical    10
   distribution, the remaining points are allocated to fit the assumed distribution.
                   Conclusions
• Until DCL and ER simulations are done:
  – Suggest to keep tentatively RCP120/300.
  – Come back to it in 2012/2013
  – Make a note:
     • DCL tend to become RCP400, pending final FAA
       simulations. SPR stays draft until mid/end 2013!
     • ACSP and ATSU are recommendations-> Importance is that
       (ACSP + ATSU + AC) need to meet RCTP.
     • Also Responder & Initiator times are recommendations for
       HMI design, training and operations.
     • Requirements are: RCP, TRN, RCTP and AC
        – Make AC delay 10s (95%) for all Specs; Amend 99.9% value




                                                                     11
                        Time and Continuity


Distribution of                                         Transaction Failed
Exchanged
                  Transaction valid
Transaction
                  95% of the Transactions

 Prob




         95%                                                          Lost messages
        99.9%




                                                                      8
                                            TT95   ET99.9     Time




                                                                                      12
     SRs related to Expiration Time
• In absence of response, at certain moment dialogue becomes
  operationally invalid. Indication required for safety reasons:
    – SR-GD-CPDLC-15 (Continental)
      The ground system shall indicate to the controller when a required
      response for a message sent by the ATSU is not received within the
      required time ET(TRN).

    – SR-14 (Oceanic)
      The ATSU system shall indicate to the controller when a required
      response for a message sent by the ATSU is not received within the
      required time ET(TRN).


 • Local option (FAA) to have pre-warning, set at TT(95) to indicate to the
 controller outstanding UM
     • 1 out of 20 msg  warning
     • Probably worse than 1 out of 20 due to unpredictable POA perf!
     • Tuning required!
                                                                              13
RCP Specs ENR-2




                  14
       Timings ENR-2: GOLD-v1
            RCP communication Transaction Time and Continuity

RCP Type                   RCP240                        RCP 400
Transaction Time            ET (sec)        TT (sec)      ET (sec)   TT (sec)
Parameter                   C=99.9%         C=95%         C=99.9%    C=95%
Transaction Time               240             210           400       350
                              RCP Time Allocations
Initiator                       30             30            30        30
TRN                            210             180           370       320
                              TRN Time Allocations
Responder                       60             60            60        60
RCTP                           150             120           310       260
                                 RCTP Allocations
ATSU                            15             10            15        10
ACSP                           120             100           280       240
Aircraft                        15             10            15        10
                                       Notes
Note 1: Allocations based on arithmetic sum
Q: Response time: Does it represent worst case, i.e. complex msg?               15
                Demo New Timings ENR-2
•       At one hand desire to use a single approach (Stats
•       On the other hand, large population of AC are certified/ops
        approved with curent GOLD specs
•       Users understand curent GOLD and are used to it.
•       Better not to touch with one exception:
    –         Current GOLD should be changed for 99.9% Responder.
    –         Stats shows this is constantly not met. Seize the opportunity to
              amend?

•       Did Statistical approach for demo, based on the following:
    1.        ATSU and AC delays as in RCP120/RCP300
    2.        RCP240 only operated with SATCOM
                 –   Based on statistics, mentioned at SG-mtg Sep11, ACSP is reduced to 60s(95%)
          •      RCP400 satisfies HFDL operations
    3.        Kept Human Response time the same for RCP240/400
          –      Same time 99.9% and 95% not realistic  see previous slide


                                                                                              16
              Demo Timings ENR-2
             RCP communication Transaction Time and Continuity

RCP Type                    RCP240                        RCP 400
Transaction Time             ET (sec)        TT (sec)      ET (sec)         TT (sec)
Parameter                    C=99.9%         C=95%         C=99.9%          C=95%
Transaction Time                240             125           400             273
                               RCP Time Allocations
Initiator                        30             13             30              13
TRN                             210             110             ?             273
                               TRN Time Allocations
Responder                       166             72             166             72
RCTP                            143             65              ?             245
                                  RCTP Allocations
ATSU                             14              6             15               6
ACSP                            138             60              ?             240
Aircraft                         16              7             15               7
                                        Notes
Note 1: The bolded values represent the constraining points in the assumed statistical
distribution, the remaining points are allocated to fit the assumed distribution         17

								
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