ACAS Test Questions and Complete
Solutions Graded A+
what was ACAS I designed to do? - Answer: the first airborne collision avoidance system, ACAS I, was
designed to provide traffic information between aircraft using SSR transponders that are independent of
ground radar units.
what was ACAS II designed to do? - Answer: ACAS II improves on ACAS I by also providing manoeuvre
advice in the pitching plane to avoid conflict..
what does EU-OPS require of new aircraft in terms of ACAS? - Answer: EU-OPS require new aircraft with
more than 19 passenger seats or with a MTOM of more than 5700Kg to carry and use ACAS II.
what is required of aircraft registered outside of EASA to operate in European RVSM airspace? - Answer:
aircraft of more than 5700Kg registered outside of EASA must have ACAS II to operate in European
RVSM airspace or in the North Atlantic region.
how does the TCAS system operate? - Answer: the TCAS system uses a mode S transponder to
interrogate the SSR transponders of nearby aircraft to plot the relative position and velocities. their
track and closing speed is computer and where a collision risk is identified, issues a warning to the crew.
what data is included in the squitter package? - Answer: the data transmitted in the squitter package
depends on the level set in the system but at minimum it contains and ICAO 24-bit identification code
and its pressure altitude.
how many data points do extended squitters carry? - Answer: extended squitters, used in ADS-B, carry
49 individual data points.
how are bearings obtained? - Answer: bearings are obtained using direction finding antenna.
how is distance obtained? - Answer: distance is obtained by measuring the time delay between the
transmitted and received signals.
, what happens if the computed time to impact is very small? - Answer: TCAS can, if the computed time to
impact is small, generate pitch commands.
what does the TCAS system protect? - Answer: the TCAS system protects a small area of airspace around
the aircraft where a collision is possible.
how are TCAS threats determined? - Answer: TCAS threats are determined by the time to enter the
collision area, known as tau.
what are the typical times form initial intrusion to collision? - Answer: - 48 to 35 seconds to enter the
caution area from initial intrusion.
- 35 to 15 seconds to enter the danger area from initial intrusion..
what conditions require the issue of a TA? - Answer: aircraft that are assessed as being likely to enter the
collision area in 48 to 35 seconds results in a traffic advisory.
what is the audio alert of a TA? - Answer: TRAFFIC TRAFFIC
what conditions require the issue of an RA? - Answer: if the time to enter the collision area reduces to
35 to 15 seconds, TCAS II will generate a resolution advisory.
what is an RA? - Answer: a resolution advisory is an audio command in the form of a manoeuvre to avoid
collision.
what is a TA? - Answer: a traffic advisory is a caution issued to the crew regarding nearby aircraft.
what is the audio alert of an RA? - Answer: - DESCEND DESCEND.
- CLIMB CLIMB.
- INCREASE CLIMB.
- INCREASE DESCENT.
- DESCEND DESCND NOW.
Solutions Graded A+
what was ACAS I designed to do? - Answer: the first airborne collision avoidance system, ACAS I, was
designed to provide traffic information between aircraft using SSR transponders that are independent of
ground radar units.
what was ACAS II designed to do? - Answer: ACAS II improves on ACAS I by also providing manoeuvre
advice in the pitching plane to avoid conflict..
what does EU-OPS require of new aircraft in terms of ACAS? - Answer: EU-OPS require new aircraft with
more than 19 passenger seats or with a MTOM of more than 5700Kg to carry and use ACAS II.
what is required of aircraft registered outside of EASA to operate in European RVSM airspace? - Answer:
aircraft of more than 5700Kg registered outside of EASA must have ACAS II to operate in European
RVSM airspace or in the North Atlantic region.
how does the TCAS system operate? - Answer: the TCAS system uses a mode S transponder to
interrogate the SSR transponders of nearby aircraft to plot the relative position and velocities. their
track and closing speed is computer and where a collision risk is identified, issues a warning to the crew.
what data is included in the squitter package? - Answer: the data transmitted in the squitter package
depends on the level set in the system but at minimum it contains and ICAO 24-bit identification code
and its pressure altitude.
how many data points do extended squitters carry? - Answer: extended squitters, used in ADS-B, carry
49 individual data points.
how are bearings obtained? - Answer: bearings are obtained using direction finding antenna.
how is distance obtained? - Answer: distance is obtained by measuring the time delay between the
transmitted and received signals.
, what happens if the computed time to impact is very small? - Answer: TCAS can, if the computed time to
impact is small, generate pitch commands.
what does the TCAS system protect? - Answer: the TCAS system protects a small area of airspace around
the aircraft where a collision is possible.
how are TCAS threats determined? - Answer: TCAS threats are determined by the time to enter the
collision area, known as tau.
what are the typical times form initial intrusion to collision? - Answer: - 48 to 35 seconds to enter the
caution area from initial intrusion.
- 35 to 15 seconds to enter the danger area from initial intrusion..
what conditions require the issue of a TA? - Answer: aircraft that are assessed as being likely to enter the
collision area in 48 to 35 seconds results in a traffic advisory.
what is the audio alert of a TA? - Answer: TRAFFIC TRAFFIC
what conditions require the issue of an RA? - Answer: if the time to enter the collision area reduces to
35 to 15 seconds, TCAS II will generate a resolution advisory.
what is an RA? - Answer: a resolution advisory is an audio command in the form of a manoeuvre to avoid
collision.
what is a TA? - Answer: a traffic advisory is a caution issued to the crew regarding nearby aircraft.
what is the audio alert of an RA? - Answer: - DESCEND DESCEND.
- CLIMB CLIMB.
- INCREASE CLIMB.
- INCREASE DESCENT.
- DESCEND DESCND NOW.
