1 / 16

OPA Issues and Potential resolutions

OPA Issues and Potential resolutions. SG Meeting of WG78/SC214 08-12 June 2009, Maastricht UAC. Overview. The Allocation Process. Timing values CPDLC transactions. Data Communication Transaction and allocations. Statistical distribution for delays. ET (TRN). 0.06. 0.05. 0.04.

jane
Download Presentation

OPA Issues and Potential resolutions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. OPA Issues and Potential resolutions SG Meeting of WG78/SC214 08-12 June 2009, Maastricht UAC

  2. Overview The Allocation Process Timing values CPDLC transactions

  3. Data Communication Transaction and allocations

  4. Statistical distribution for delays ET (TRN) 0.06 0.05 0.04 Sum of Exp 0.03 pdf Log Normal 0.02 0.01 0 0 20 40 60 80 100 120 -0.01 Delay (seconds) • Assumption: • Allocated delays are independent; • Each delay is modelled as an Exponential distribution • Same ET(TRN): Larger allocated values than arithmetic allocations • Example: ET(TRN)=120s: • Arithmetic: ATSU=4s; AC=6s; ACSP=10s; Responder=100s • Exp sum: ATSU=14s; AC=10s; ACSP=18s; Responder=114s

  5. Issues statistical distribution • Reliability of oper data to be improved • Need more data to examine the assumed (Expon) model • More powerful tool for handling large amount of data • Current MUAC oper data: Longer delays in tail of the curve • Solutions are underway, requires time: not before Mid 2010 • Mapping of model is an approximation • Especially for ‘Tech Comms’ (neither Expon nor Lognormal) • Depends on A/G technology, network typology • Should ‘Tech Comms’ allocations become recommendations? • Initiator and Responder are operationally driven  remain PRs • Drives HMI design

  6. Overview The allocation Process Timing values CPDLC appliation

  7. Timer Overview: tts tts , , latency Optional FC notified Latency Time Check aircraft voice intervention optional voice T_upl T_upl T_dwn T_dwn T_dwn intervention (clearance) (clearance) (response) (response) (ERROR) ground ATCo ATCo notified notified tts or TRN99.9 or ETTRN Timer Overview:Ground-initiated CPDLC transaction • Need for ‘latency time check’ and Ground Timer tts to satisfy SO of OH-CPDLC-10: CPDLC message, impacting separation is not received (Undetected)’

  8. Specifying the timing requirements :Ground-initiated CPDLC transaction • Ground Timer tts and the ‘latency time check’: • Safety driven (OSA): No values • Operationally driven (OSD, OPA): Values • Ground timer tts: • OSA  SR-GD-CPDLC-15 • OSD  ACM-OR-04 • OPA  PR-CPDLC-05 (En-route) • INTEROP  CPC-IR-169 • Latency Time check (aircraft) • OSA  SR-AC-CPDLC-08 • OSD  CPC-OR-92: value TBD • OPA  N/A • INTEROP  N/A

  9. Time/Probability DistributionCPDLC transaction Max acceptable transaction time, after which the initiator reverts to an alternative procedure (Time is linked with Continuity (set at 99.9%)) Nominal time at which 95% of all transactions, that are initiated, are completed. Continuity: Probability that a transaction completes within the expiration time

  10. Issue 1 Timing values: Ground-initiated CPDLC transaction • OSA, OPA assessment of CPDLC on a per airspace basis • Interop also distincts tts on a per airspace basis • OSD, specification of timing values on a per service basis • Should keep consistency -> In OSD: values in CPDLC section and specify per airspace. • 4D-TRAD: Define flight phase ‘4D-TRAD service area’ for 95%, 99.9% values?

  11. Issue 2 Timing values:Ground-initiated CPDLC transaction

  12. OSD: The Consequences … • Undermining CPDLC performance: • Continuity requirement is not met • Early interruption (e.g. ER at 95 %tile=55s rather than at 99.9 %tile=120s) • Increase Controller workload • Unnecessary reversion to voice: Still enough time to receive reply by data link • Controller tends to draw attention to the ‘timed-out’ aircraft • More time-outs when network load increases  Nuisance • Does a well designed HMI need a ‘remember’ function for this? • Safety risk: Controller ignorance when alerts too frequent • Solution for OSD: • The role and value of the timer within the OSD same as OPA • Value is at 99.9%tile, i.e. time at which the transaction expires and is no longer valid. • Recommend to add note in OSD underneath the time requirements: • Upon time-out, the transaction is no longer valid

  13. Latency Time Check:CPDLC transactions • Aircraft • OSA: SR-AC-CPDLC-08 • OSD: CPC-OR-92 (abnormal behaviour) • Ground • OSA: SR-GD-CPDLC-17 • OSD: CPC-OR-91 (abnormal behaviour) • OPA assesses normal mode  No ‘latency time check’ specification • OSA (for AC): Upper limit (ETTRN) determined by SR-AC-CPDLC-08 “When a received message contains a time stamp that indicates that the ETTRN time has been exceeded, the aircraft system shall either discard the message and inform the controller or display the message to the flight crew with an appropriate indication.” • OSD: Should get operationally meaningful value • Smaller value required than ETTRN

  14. Aircraft Ground Latency Time Check:Proposed Values in OSD

  15. Validity E-t-E Time values for CPDLC • Values in SPR: tentative (from ED120/DO290) • En-Route • for IP1: Validated through PETAL and MIAMI • Adequate for ENV-A time frame? • Check MUAC Oper data for 95 %tile and 99.9 %tile • Do simulations and trials • TMA and Airport (non-DCL) and 4D-TRAD • Adequate for ENV-A time frame? • Do simulations and trials • Future expectations on timings • Difficult to predict values more than 10 years ahead • 4D-TRAD service is only for ENV-A • Should the SPR only consider ENV-A?

  16. Thank You

More Related