Informative slides on Anti collision system in Airplanes.

1. Traffic Collision Avoidance System
(TCAS)

2. Submitted to : Ma’am Abeer Bashir
Submitted by :
Ammar Ahmed UET-08
M.Rizwan UET-29
M.Sheharzad UET-18
Sohal Shezad Uet-09
M. Khizar UET-21

3. History :
In 1956 a deadly collision took place over Grand
Canyon between a United Airlines DC-7 and a TWA Flight.
At that time it was the deadliest accident, so research
started to develop an anti-collision system to avoid such
kind of incidents in future. In 1960-70’s many collision
avoidance systems were designed but gave useless alarms
when tested in heavy traffic regions. In 1978 a PSA Flight
182 collided with a 4-seated small plane near San Diego
Airport, killing all 144 passengers on board. After this
incident Federal Aviation Authority (FAA) developed a
system which now called TCAS.

4. Abstract :
A traffic collision avoidance system both
pronounced as TCAS, and (te-kas) is an airliner collision
avoidance system designed specifically to reduce the
incidents of mid air collisions between airplanes. It checks the
airspace around an airplane for other airliners which are
equipped with an active transponder device, irrespective
of air traffic control commands it warns pilots about the
existence of other same instrument prepared airliner which
may result in a mid air collision (MAC).It uses cross
communication with other airliner which is equipped with the
same device. In the case of any intruder it sounds an alarm in
the cockpit which tells the pilot that there is another airliner
flying in the same airspace with a gap of less then 500 feets.

5. Working :
It makes sure to maintain a distance of at
least 500 ft among both of these two airliners. This is how
this system works. specific range about their positions
(through the 1.03 GHz radio frequency and all other
airliners reply to the monitoring cross communications via
(1.09 GHz). This cross-examination and response process
can occur more than one times per second. This system
creates a multi dimensional map of airliners in the airspace,
keeping in view their height (as reported by the monitoring
airliner) and behavior (by the respective directional aerial
from the reaction). By checking existing range and height
difference to probable expected values, it determines if a
possible accident risk exists.

7. •
Mechanism of TCAS :
TCAS consists of following
mechanism.
• TCAS computer unit.
• Aerials.
• Cockpit Presentation.

8. Technology Before TCAS:
Before the invention of TCAS,
radars were used to navigate the positions of an
airliners and in the case of any intruder flying in the
same airspace, it was the ATC’s responsibility to make it
sure that both of these airliners pass by each other
with enough distance so that they made not end in a
collision. But this idea was proven wrong very soon
when a number of collisions occurred in a calendar
year. In 1956 a deadly collision took place over Grand
Canyon between a United Airlines DC-7 and a TWA
Flight.

9. Versions of TCAS :
TCAS 1 :
TCAS I systems are able to monitor the traffic situation around a plane (to
a range of about 40 miles) and offer information on the approximate bearing and
altitude of other aircraft.
TCAS 2 :
TCAS II is the first system that was introduced in 1989 and is the current
generation of instrument warning TCAS, used in the majority of commercial
aviation aircraft .
TCAS 3 :
TCAS III was envisioned as an expansion of the TCAS II concept to include
horizontal resolution advisory capability.
TCAS 4:
TCAS IV uses additional information encoded by the target aircraft in the
Mode S transponder reply (i.e. target encodes its own position into the
transponder signal) to generate a horizontal resolution to an RA

10. TCAS 7.1 :
A new edition has been planned but has not
been implemented because the research is still in progress
on it named TCAS 7.1, it involves certain new features in it
like dispatching an alarm before 100 feets mark between
two airliners and making a decisions even right before the
accident, which means that it can change the direction of
airliner keeping in view the information being transmitted
and received by the transponders of both airliners.
Researchers are discussing upon the idea to give TCAS 7.1
more priority than the commands of Air Traffic Control
(ATC). Because it has more reliability and especially it is
able to make quick and fast decisions in very less time.

12. Conclusions :
• Although the system rarely suffers from fake alarms, pilots
are now under severe instructions to look upon all TCAS
messages as valid alerts demanding an instant, high
precedence rejoin.
• Only Wind shear Detection and GPWS alerts and warnings
will have higher precedence than the TCAS.
• If one airliner follows a TCAS RA and the other follows
opposing ATC instructions, a collision can occur, so both
airliners must follow the instructions of TCAS.
• This system thus improved the safety measures and hence
number of collisions decreased after it’s implementation

13. The End