Definition of Spacing based on
Spacing 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
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.
Spacing Definition based on SRP
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Basic requirements on a
definition of spacing
•
Common to all stakeholders
All stakeholders must have the same definition of the spacing
dist/time.
•
Operational functionality
For maximum benefit spacing should be possible in as many
flight situations as possible.
•
Generic Properties
The same generic definition should encompass:
– ”All” ASAS spacing applications (C&P excluded)
– Both distance and time definitions
– ADS-B and TIS-B technical solutions
Spacing Definition based on SRP
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Spacing only
The SRP spacing
definition does not
provide separation!!!
Spacing Definition based on SRP
4
Spacing only
The SRP spacing
definition is a tool to
enhance traffic flow!!!
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP
Used to derive the spacing distance Ss
F
L
SRP
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (fixed)
Used to derive the spacing distance Ss
F
L
SRPf
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
F
L
SRPd
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
•
Let´s start with fixed SRP
Spacing Reference Point SRP (fixed)
Used to derive the spacing distance Ss
F
L
SRPf
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (fixed)
F
Used to derive the spacing distance Ss
L
SRPf
Ls = (L – W1 - SRP)
W1
Fs = (F – W1 - SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
F
•
Spacing Reference Point SRP (fixed)
W1
Used to derive the spacing distance Ss
SRPf
L
W4
Ls = (L – W3 – W4 - SRP)
W2
Fs = (F – W1 - W2 – W3 – W4 - SRP)
W3
Ss = Fs - Ls
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (fixed)
W1
Used to derive the spacing distance Ss
L
SRPf
Ls = (L – W2 – W3 – W4 - SRP)
W2
W4
Fs = (F – Y3 – W3 – W4 - SRP)
W3
Ss = Fs - Ls
Spacing Definition based on SRP
F
Y3
12
Link sequence
Sequence determined by AMAN/Controller
Spacing executed by indiviual aircraft/pilots
Separation monitored by Controller
SRP
Spacing Definition based on SRP
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Basic Idea
•
Let´s go on to dynamic SRP
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
F
L
SRPd
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
L
5
s
L-track = 260 dgr
F-track = 275 dgr
F
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
Spacing Definition based on SRP
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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
F
Delta-track = 30 dgr
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
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
L
L-track = 260 dgr
20 s
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
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
L
L-track = 260 dgr
30 s
F-track = 350 dgr
Delta-track = 90 dgr
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
Spacing Definition based on SRP
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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
45 s
Delta-track = 135 dgr
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
SRP = 45 sec
F
ahead of
target
Standard rate turn = 3 dgr/sec = 135 dgr/45 sec
Spacing Definition based on SRP
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Basic Idea
•
Spacing Reference Point SRP (dynamic)
Used to derive the spacing distance Ss
L
L-track = 260 dgr
60 s
F-track = 080 dgr
Delta-track = 180 dgr
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
Spacing Definition based on SRP
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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
60 s
Delta-track = 180 dgr
Ls = (L – SRP)
Fs = (F – SRP)
Ss = Fs - Ls
SRP = 60 sec
ahead of
F
target
Standard rate turn = 3 dgr/sec = 180 dgr/60 sec
Spacing Definition based on SRP
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Let´s introduce curves
2T algorithm
•
Two Turn distance algorithm
Used 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
Spacing Definition based on SRP
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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 at:
www.nup.nu
Documents/General Documents/sep-algo
Spacing Definition based on SRP
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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.
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
30
2T distance
algorithm using
SRPd
L
60s
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
F
++
Spacing Definition based on SRP
31
2T distance
algorithm using
SRPd
L
60s
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
F
++
Spacing Definition based on SRP
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2T distance algorithm
using SRPd
L
57s
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
F
++
Spacing Definition based on SRP
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2T distance algorithm
using SRPd
L
54s
Ls = (L – SRP)
F
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
34
2T distance algorithm
using SRPd
L
51s
Ls = (L – SRP)
F
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
35
2T distance algorithm
using SRPd
L
48s
Ls = (L – SRP)
F
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
36
2T distance algorithm
using SRPd
L
45s
Ls = (L – SRP)
F
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
37
2T distance algorithm
using SRPd
L
42s
Ls = (L – SRP)
F
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
38
2T distance algorithm
using SRPd
L
36s
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
39
2T distance algorithm
using SRPd
L
30s
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
40
2T distance algorithm
using SRPd
L
25s
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
41
2T distance algorithm
using SRPd
L
22s
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
42
2T distance algorithm
using SRPd
19s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
43
2T distance algorithm
using SRPd
17s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
44
2T distance algorithm
using SRPd
14s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
45
2T distance algorithm
using SRPd
11s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
46
2T distance algorithm
using SRPd
8s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
47
2T distance algorithm
using SRPd
6s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
48
2T distance algorithm
using SRPd
3s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
49
2T distance algorithm
using SRPd
0s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
50
2T distance algorithm
using SRPd
0s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
51
2T distance algorithm
using SRPd
0s
L
F
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
++
Spacing Definition based on SRP
52
2T distance algorithm
using SRPd
Ls = (L – SRP)
Fs = (F – 2T algorithm - SRP)
Spacing = Fs - Ls
+
Spacing Definition based on SRP
53
Operational applicability of
SRPd
•Merging
In 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
Spacing Definition based on SRP
54
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)
Spacing Definition based on SRP
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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
Spacing Definition based on SRP
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Operational applicability with
SRP
•
In-Trail
• STAR (incl. diff STAR)
• Straight and curved
•
ADS-B
ADS-B
TIS-B
ADS-B
ADS-B
TIS-B
Merging
• Merging STARs
• Free space merging
Spacing Definition based on SRP
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The Spacing Algorithm (highlevel)

Define SRP method
1.

Define distances to SRPf
2.
3.


Select SRP method to be used
Retrieve Follower distance to SRP from FMS
Retrieve Leader distance to SRP from ADS-B data
or
Define distances to SRPd
2.
3.
Calculate Leader distance to SRP
Calculate Follower distance to SRP
Derive spacing distance and time
4.
5.
Compare Leader dist to SRP with Follower distance to SRP
Convert spacing distance to spacing time by dividing with
follower GS
Spacing Definition based on SRP
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Thank You
•
•
•
Remember!
This is not a final definition of spacing
…but
•
– It may be a starter!!!
Spacing Definition based on SRP
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