TCAS, GPWS And EFIS Flashcards
TCAS
- AKA ACAS
- Airborne Collision Avoidance
- Mandatory for aircraft over 5700kg or carrying more than 19 pax
- TCAS I and TCAS II - I is cheaper and is mainly found on GA aircraft
- Sends an interrogation code every second. Computes the replies to work-out the trajectory of every other aircraft, compares it to its own trajectory and give an alert if possible conflict.
Traffic Advisory (TA)/ Resolution Advisory (RA)
- TCAS II can provide TA and RA, TCAS I can only provide TA.
Traffic Advisory (TA)
When TCAS system detects a possible conflict within the next 48 seconds, sends an oral and visual warning to alert the pilot.
Resolution Advisory (RA)
Only available with TCAS II systems. Will come on if the TA does not get resolved.
Kicks in when there is less than 35 seconds before the conflict and the aircraft is within +/- 600ft.
Gives oral order to the PIC to avoid possible collision, with a visual target
Ground Promximity Warning System (GPWS)
- Invented to reduce number of controlled flight into terrain crashes.
- Radar altimeter - send radar signal straight down and then back up. Measures distance and tells us how far above the ground that we are.
Issue: Only measure terrain below you, not what is in front of you.
E-GPWS
- Enhanced GPWS
- Uses terrain database onboard the aircraft in conjunction with the aircraft’s onboard navigation system to predict terrain conflicts.
- Knows that there is terrain below and around the aircraft
TAWS
- Terrain Awareness Warning System (TAWS)
- Used to describe GPWS and E-GPWS
Class A TAWS
Must provide terrain information to be presented on a display system. Must provide indications of imminent contact with the ground for the following conditions:
- Excessive rate of descent
- Excessive closure rate to terrain
- Negative climb rate or altitude los after take-off
- Flight into terrain when not in landing configuration
- Excessive downward deviation from an ILS
- A voice call-out “five hundred” when the airplane descents to 500ft above the terrain or nearest runway elevation
Class B TAWS
Doesn’t;t require a display. Must provide indications of imminent contact with the ground for the following conditions:
- Excessive rate of descent
- Negative climb rate or altitude los after take- off
- A voice call-out “five hundred” when the airplane descents to 500ft above the terrain or the nearest runway elevation.
Class C TAWS
Configurable system, designed for voluntary usage.
Electronic Flight Information System (EFIS)
Digitally displays flight information to a pilot, as opposed to using conventional instruments and gauges.
Graphic Display unit (GDU)
The screen which displays the information.
- In case of a failure of the PFD, the MFD can be used as a back-up PFD
Symbol/signal Generator (SG)
- Computer at the centre of the entire system.
- Receives digital data and sends a signal (symbol) to the GDUs.
Air Data Computer (ADC)
- Processes raw data from pitot tubes, static vents, temperature probes and angle of attack indicators, in order to obtain key information.
- Sends the digital data it has computed to the signal generator.
Attitude Heading Reference System (AHRS)
- Replaces gyroscopic instrument.
- Has Inertial Measurement Unit (IMU) - uses accelerometers and electronic gyroscope in the three axis.
Engine Indication and Crew Alerting System (EICAS)
- Displays a range of data
- Alerts are displayed on screens to enhance the situational awareness of the crew
- Only shows essential information
EFIS Failure
Caused by:
- Loss of electrical power
- Most systems automatically turn of MFD if the alternator fails so you will have a bit of time before the battery is flat
- Back up alternator is usually provided - smaller than main alternator and typically needs to run around 80% of cruise RPM to provide sufficient electricity
