Definition of Spacing based on Spacing Reference Point, SRP

1
Definition of Spacing based onSpacing Reference
Point, SRP

• Presentation of a proposal for a generic
  definition of spacing to be used for ASAS spacing
  applications.
• Most of the work on a spacing definition has been
  performed by SAS within the frame of NUP I and
  NUP II.
• Presented at the ASAS Thematic Network Workshop
  07OCT 2003 by
• Capt. Michael Agelii, representing Aviator System

2
Need for a definition of spacing

• Spacing is a defined distance between two
  aircraft denoted as Leader and Follower
• In order to measure a distance between the leader
  and follower in space you must define along which
  line or curves in space the distance shall be
  measured.
• The great circle track between two aircraft is a
  truly useful representation of spacing only in
  the special case when both aircraft are flying
  with the same track and in line.
• In order to be able to use spacing operationally
  where aircraft frequently alter their track, we
  must broaden the definiton to encompass curves in
  space and track changes.
• It is an advantage to convert the defined
  distance to time by using follower ground speed.

3
Basic requirements on a definition of spacing

• Common to all stakeholdersAll stakeholders must
  have the same definition of the spacing
  dist/time.
• Operational functionalityFor maximum benefit
  spacing should be possible in as many flight
  situations as possible.
• Generic PropertiesThe same generic definition
  should encompass
• All ASAS spacing applications (CP excluded)
• Both distance and time definitions
• ADS-B and TIS-B technical solutions

4
Spacing only

• The SRP spacing definition does not provide
  separation!!!

5
Spacing only

• The SRP spacing definition is a tool to enhance
  traffic flow!!!

6
Basic Idea

• Spacing Reference Point SRPUsed to derive the
  spacing distance Ss
• SRP

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
7
Basic Idea

• Spacing Reference Point SRP (fixed)Used to
  derive the spacing distance Ss
• SRPf

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
8
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss
• SRPd

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
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Basic Idea
Lets start with fixed SRP

• Spacing Reference Point SRP (fixed)Used to
  derive the spacing distance Ss
• SRPf

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
10
Basic Idea

• Spacing Reference Point SRP (fixed) Used to
  derive the spacing distance Ss
• SRPf

F
L
W1
Ls (L W1 - SRP) Fs (F W1 - SRP) Ss Fs -
Ls
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Basic Idea
F

• Spacing Reference Point SRP (fixed) Used to
  derive the spacing distance Ss
• SRPf

W1
L
W2
W4
Ls (L W3 W4 - SRP) Fs (F W1 - W2 W3
W4 - SRP) Ss Fs - Ls
W3
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Basic Idea

• Spacing Reference Point SRP (fixed) Used to
  derive the spacing distance Ss
• SRPf

W1
L
W2
W4
Ls (L W2 W3 W4 - SRP) Fs (F Y3 W3
W4 - SRP) Ss Fs - Ls
W3
F
Y3
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Link sequence
Sequence determined by AMAN/Controller Spacing
executed by indiviual aircraft/pilots Separation
monitored by Controller
SRP
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Basic Idea
Lets go on to dynamic SRP

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss
• SRPd

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
15
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
16
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
17
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

F
L
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
18
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

F
L
L-track 260 dgr F-track 260 dgr Delta-track
0 dgr
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
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Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

F
L
L-track 260 dgr F-track 260 dgr Delta-track
0 dgr
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
Standard rate turn 3 dgr/sec 180 dgr/60 sec
20
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
F
5 s
L-track 260 dgr F-track 275 dgr Delta-track
15 dgr
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
SRP 5 sec ahead of target(based on Leader
ground speed)
Standard rate turn 3 dgr/sec 15 dgr/5 sec
21
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
10 s
L-track 260 dgr F-track 290 dgr Delta-track
30 dgr
F
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
SRP 10 sec ahead of target
Standard rate turn 3 dgr/sec 30 dgr/10 sec
22
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
20 s
L-track 260 dgr F-track 320 dgr Delta-track
60 dgr
F
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
SRP 20 sec ahead of target
Standard rate turn 3 dgr/sec 60 dgr/20 sec
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Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
L-track 260 dgr F-track 350 dgr Delta-track
90 dgr
30 s
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
F
SRP 30 sec ahead of target
Standard rate turn 3 dgr/sec 90 dgr/30 sec
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Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
L-track 260 dgr F-track 035 dgr Delta-track
135 dgr
45 s
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
F
SRP 45 sec ahead of target
Standard rate turn 3 dgr/sec 135 dgr/45 sec
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Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
L-track 260 dgr F-track 080 dgr Delta-track
180 dgr
60 s
F
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
SRP 60 sec ahead of target
Standard rate turn 3 dgr/sec 180 dgr/60 sec
26
Basic Idea

• Spacing Reference Point SRP (dynamic)Used to
  derive the spacing distance Ss

L
L-track 260 dgr F-track 080 dgr Delta-track
180 dgr
60 s
Ls (L SRP) Fs (F SRP) Ss Fs - Ls
SRP 60 sec ahead of target
F
Standard rate turn 3 dgr/sec 180 dgr/60 sec
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2T algorithm
Lets introduce curves

• Two Turn distance algorithmUsed to derive the
  spacing distance Ss closer to real flight path

L
60 s
Ls (L SRP) Fs (F 2T algorithm - SRP) Ss
Fs - Ls
F
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2T algorithm

• The Two Turn distance algorithm has been
  developed in a thesis by mathematics student
  Robert Lundmark on assignment by SAS within the
  framework of NUP II.
• The complete thesis can be downloaded from the
  NUP webside atwww.nup.nu Documents/General
  Documents/sep-algo

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2T algorithm

• The shortest possible way to fly from follower
  position to leader position and end up in the
  same direction is at most via two turns and a
  straight line.

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2T algorithm

• The shortest possible way to fly from follower
  position to leader position and end up in the
  same direction is at most via two turns and a
  straight line.

Leader position can of course be substituted by
SRPd
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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

45
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

46
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

47
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

48
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

49
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

50
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

51
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

52
2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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2T distance algorithm using SRPd
Ls (L SRP) Fs (F 2T algorithm -
SRP) Spacing Fs - Ls

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Operational applicability of SRPd

• MergingIn managed or unmanaged airspace in order
  to establish the desired spacing in the required
  sequence.
• Spacing
• Spacing to TIS-B aircraft
• Spacing to aircraft not flying a predefined route

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Input data to the definition of Ss

• Leader input data (ADS-B/TIS-B)
• Position
• Track
• Velocity (GS)
• Distance to SRP Ls (fixed SRP only)
• SRPf (fixed SRP only)
• Follower input data (onboard ADS-B for ground)
• Position
• Track
• Velocity (GS)
• Distance to SRP Fs
• SRPf (fixed SRP only)

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Addition to basic ADS-B data(for fixed SRP only)

• Distance to SRP (Ls)
• Broadcast as extension to data
• Distance to SRP as 10 bit info (99.9)
• SRP
• Broadcast as extension to data
• SRP as lat, long or Nav database reference

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Operational applicability with SRP

• In-Trail
• STAR (incl. diff STAR) ADS-B
• Straight and curved ADS-B TIS-B
• Merging
• Merging STARs ADS-B
• Free space merging ADS-B TIS-B

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The Spacing Algorithm (highlevel)

• Define SRP method
• Select SRP method to be used
• Define distances to SRPf
• Retrieve Follower distance to SRP from FMS
• Retrieve Leader distance to SRP from ADS-B data
• or
• Define distances to SRPd
• Calculate Leader distance to SRP
• Calculate Follower distance to SRP
• Derive spacing distance and time
• Compare Leader dist to SRP with Follower distance
  to SRP
• Convert spacing distance to spacing time by
  dividing with follower GS

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Thank You

• Remember!
• This is not a final definition of spacing
• but
• It may be a starter!!!