Overview of ACAS II / TCAS II

32 Pages·2009·0.29 MB·English

Overview of ACAS II / TCAS II
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this presentation.
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Version 1.4 –7 January 2009
Maastricht ATC 2006
ACAS
ACAS: Airborne Collision Avoidance System
(cid:122)
ACAS is a set of standards defined by ICAO:
(cid:122)
an ACAS I issues Traffic Advisories (TAs)
(cid:122)
an ACAS II issues Resolution Advisories (RAs), in addition to TAs, in the
(cid:122)
vertical plane only
an ACAS III issues Resolution Advisories (RAs), in addition to TAs, in both the
(cid:122)
vertical and in the horizontal plane
Only ACAS II standards have been defined and approved
(cid:122)
ACAS equipage automatically implies Mode S equipage
(cid:122)
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Version 1.4 © 2009 EUROCONTROL
TCAS
TCAS: Traffic alert and Collision Avoidance System
(cid:122)
TCAS II v7.0 is the current in-use system for Europe
(cid:122)
An upgrade to TCAS II v7.1 is planned – the implementation schedule is not
(cid:122)
known yet
TCAS II v6.04a is still in-use in some countries, notably USA
(cid:122)
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Version 1.4 © 2009 EUROCONTROL
ACAS II principles
Intended as a last resort protection against risk of collision
(cid:122)
Designed for collision avoidance only
(cid:122)
Independent of ground-based systems and the auto-pilot and of
(cid:122)
NAV systems
ACAS algorithms and parameters as far as possible chosen to be
(cid:122)
compatible with separation standards - but:
Does not warn of loss of separation
(cid:122)
Sometime generate unnecessary (nuisance) alerts
(cid:122)
Sense of RAs coordinated between ACAS equipped aircraft
(cid:122)
Complying with RAs can result in deviation from clearance
(cid:122)
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Situation in the world
Europe:
(cid:122)
The carriage of ACAS II has been mandatory from 1-1-2005 for all civilian
(cid:122)
turbine-engined aircraft carrying more than 19 passengers or with the maximum
take-off mass more than 5700 kg
USA:
(cid:122)
TCAS II has been mandatory in US airspace since 1994, for all civilian turbine-
(cid:122)
engined aircraft carrying more than 30 passengers
Three manufacturers (Rockwell-Collins, ACSS, Honeywell)
(cid:122)
ICAO has recommended world-wide mandatory ACAS II carriage
(cid:122)
(1-1-2003)
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Version 1.4 © 2009 EUROCONTROL
Equipment description
MODE S
TCAS DIRECTIONAL
ANTENNA
ANTENNA
AURAL
ANNUNCIATION
COORDINATION
& INHIBITION
EFIS or TCAS DISPLAY
TCAS II MODE S
UNIT XPDR
RADAR ALTIMETER AIR DATA TCAS + SSR
COMPUTER GEARS & CONTROL
(ADC) FLAPS PANEL
RADAR ALTIMETER
ANTENNA LOWER TCAS MODE S
ANTENNA ANTENNA
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Version 1.4 © 2009 EUROCONTROL
Functions
Surveillance of adjacent transponders (range = 14 NM)
(cid:122)
Maximum number of aircraft processed = 30
(cid:122)
Determination of the alerts: TA and RA
(cid:122)
Co-ordination between two TCAS units (through the mode S data-link)
(cid:122)
Aural annunciations
(cid:122)
Display of information on Vertical Speed Indicators (VSI) or on EFIS (ND
(cid:122)
+ PFD)
Processing cycle = 1 second
(cid:122)
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Version 1.4 © 2009 EUROCONTROL
Example of IVSI-type TCAS display
(classic instrumentation)
Intruder target
Other traffic
Proximate traffic
Relative altitude (ft x 100)
Intruding traffic
Threat
Vertical trend arrow
TCAS display centre
Vertical speed needle
2-NM radius circle
Resolution advisory
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Example of EFIS with RAs displayed on
the vertical speed scale
MACH ALT HDG AP1
A/THR
FL 310
360
315
340
40
320 310
20
300
305
280
2
.818 STD
The pilot must manoeuvre the aircraft to comply with the specified vertical
speed (here: -1500 fpm)
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Version 1.4 © 2009 EUROCONTROL
Example of EFIS with RAs displayed on
the artificial horizon
SPD L-NAV ALT
M 0.82 31000
380
31400
360
340 31200
5
40
32 310
6 20
320
30800
300
280
30600
240
CRS 110
260
10 11 12
0.818 0 9 13 STD
0 8 14
The pilot acts on the aircraft attitude
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Version 1.4 © 2009 EUROCONTROL