TCAS / GPWS / TAWS stuff that matters

Question 1

TCAS alerting is based on a couple different criteria of threats… what are they?

Answer 1

• Other traffic. Aircraft not within ± 1,200 feet vertically or beyond 6 NM and not considered threats.
• Proximate traffic. Aircraft within ± 1,200 feet vertically and 6 NM, but still not considered threats.
• Traffic Advisories (TA). Target aircraft are within 6 NM and could be potentially hazardous. Depending on altitude, the time to the closest point of approach is 20 to 48 seconds.
• Resolution Advisories (RA). Target aircraft are within 6 NM and projected to be a collision threat. Depending on altitude, the time to

Question 2

What must another aircraft be equipped with for our TCAS to categotize them into 1 of 4 categories?

Answer 2

An operating Mode C or Mode S transponder providing altitude information.

Question 3

What places the TCAS in standby?

Answer 3

The TCAS is in standby when the IFF is in standby or off, or when either Mode C or Mode S are out.

Question 4

What happens when TA/RA mode is
selected on the EMCON pages?

Answer 4

the TCAS reverts to TA only mode when descending through 900 feet AGL and returns to
TA/RA mode after climbing through 1100 feet AGL.

Question 5

TCAS TA and RA aural alerts are inhibited below xxxxxxxxx feet AGL while descening and below xxxxxxxx feet AGL while climbing.

Answer 5

400 Feet AGL on the descent and 600 AGL while climbing

Question 6

TCAS ABV (above) parameters

Answer 6

ABV (above) indicates the -2700 to +8700 foot zone is selected (climb phase).

Question 7

TCAS BLW (below) parameters

Answer 7

BLW (below) indicates the +2700 to -8700 foot zone is selected (descent phase).

Question 8

TCAS NORM (normal) parameters

Answer 8

NORM (normal) indicates the ± 2700 feet zone is selected (enroute phase).

Question 9

MFD Symbology for TA / RA / Prox / Other

Answer 9

TA: Solid Yellow Circles

RA: Solid Red Squares

Prox: Solid White Diamond

Other: Open White Diamond

Question 10

TCAS cone of confusion. What is it?

Answer 10

• The TCAS has a cone of confusion within ± 10° directly above/below the aircraft. All affected MFD formats do not depict TCAS intruders within this cone.

Question 11

TCAS Special Annunciations

Answer 11

Special annunciations are generated when a TA or RA is active. For TAs, TRAFFIC is generated. TRAFFIC is removed when an RA is generated or when the TA is no longer a factor.

Question 12

TCAS Submode Engagement

Answer 12

The F/D Traffic Collision Avoidance System (TCAS) submode is engaged by pressing the AP disengage switch on either control stick when a TCAS Resolution Advisory (RA) is present and the A/R mode is not engaged.

The purpose of the mode is to provide guidance to a vertical speed target while holding the current airspeed. The TCAS submode has no effect on the roll axis.

Question 13

What happens after you engage the TCAS submode?

Answer 13

When the TCAS submode is engaged, both P and CP F/Ds, if not already on, will automatically engage. The Pitch and Thrust FMAs will depict TCAS. PACAH is disengaged if engaged. Any armed pitch/thrust modes will be disarmed. If the AP and/or ATS were engaged, they will disengage with no aural warning but the red AP/ATS warning annunciators will illuminate steady.

When the TCAS submode is engaged, the F/D will provide guidance to achieve and maintain the target vertical speed on the flight path controlling axis and to hold the existing airspeed on the speed controlling axis. The TCAS vertical speed target will be displayed on the AFCS
control panel VERT SPD window.

Question 14

GROUND PROXIMITY WARNING SYSTEM (GPWS) explanation

Answer 14

The GPWS provides warnings of dangerous ground proximity flight conditions. The GPWS inputs include the aircraft configuration (flap and gear positions), radar altitude, barometric altitude, vertical velocity, glide slope deviation, and pilot inputs. All four flight control computers process ground proximity warnings. The MC, A/PDMCs, and WCCs generate visual and aural warnings.

Question 15

GPWS Altitude Enevelope

Answer 15

The GPWS operates from radar altitudes of 50 to 10,000 feet. A ground proximity warning is issued for each of the GPWS modes of operation

Question 16

How many GPWS modes are there?

Answer 16

9 different modes

Question 17

GPWS Mode Warnings are based on what?

Answer 17

All mode warnings are based on fixed warning envelopes.

Aural and visual warnings are given when an unsafe ground proximity condition occurs.

The visual warning is presented by the GROUND PROX annunciator on both the pilot and copilot glareshield panels and the word TERRAIN displayed on the PFDs for Modes 2A and 2B.

The aural warnings are repeated until silenced or the conditions which caused the warnings are removed

Question 18

TERRAIN AWARENESS AND WARNING
SYSTEM (TAWS) explanation

Answer 18

The Terrain Awareness and Warning System (TAWS) provides situational awareness formats for the MFD and generates PFD annunciations and CAWS alerts of impending controlled flight into terrain or an obstacle when the aircraft is at or will be below the terrain’s elevation
or obstacle’s height.

Question 19

What are the 4 databses for the TAWS

Answer 19

• Worldwide Flight Map
• Tactical Flight Map
• Airport Flight Map
• Obstacle Flight Map

Question 20

TAWS normal vs. tactical vs. runway mode

Answer 20

– The normal mode is optimized for enroute flight. The MFD displays terrain even if it is up to 2000 feet below the aircraft. Normal is the default mode at power-on.

– The tactical mode is intended for the low level tactical environment. It changes the MFD colors so that yellows and reds are above the aircraft and greens are below. Terrain more than 300 feet below the aircraft is not displayed.

-The Runway mode is intended to declutter the display and reduce nuisance alerts for approach and takeoff. Colors are changed to make areas which should be safe in IMC show as black or shades of green, and some alerts are inhibited to lessen nuisance warnings.
When a CNDB runway is used in the MC’s flight plan for TOLD, the TAWS can use that runway’s data to enter runway mode.

Question 21

How to enter / select TAWS Runway Mode

Answer 21

Automatic entry within 15 NM of runway, flaps 1/2 or more, and either TOGA mode
or gear down.

Exited after climb to 1500 feet above runway OR farther than 15 NM from runway.

Question 22

Minimum Height Clearances of various TAWS modes

Answer 22

Normal: 700 feet

Tactical: 50-700 feet

Runway: Varies in steps from within 15 NM of the runway
- outside of 15 NM you get 700 feet clearance
- between 15 NM and 5 NM you get 350 feet of clearance
- betwen 5 NM ans 2 NM you get 150 feet of clearance
- Inside of 2 NM it steps down from 150 to no warnings or caws

Question 23

Windshear Alerting Profile

Answer 23

Windshear alerting is available when in TOGA mode from 70 knots TAS up to 1500 feet radar altitude and APPR when radar altitude is between 30-1500 feet.