- How does EGPWS (TAWS) operate?
o From a world surface database input & GPS it can calculate which terrain is conflicting with the aircraft and warn the pilots (forward looking)
- What is TAWS?
Terrain Awareness and Warning System will provide increased vertical situational awareness.
Continuous terrain display so that they would have perceived these terrain threats and responded to them before TAWS was required to generate warnings.
- How does TCAS interrogates intruder aircraft, and what are the symbols?
o TCAS uses transponder signals from other aircraft to determine relative positions.
o Surveillance target - Open white diamond (nearby)
o Proximity target - Solid cyan (blue) diamond (within 1200 ft + 6 miles)
o Traffic advisory - Solid yellow circle (within 20 - 48sec’s)
o Resolution advisory - Solid red square (Within 15 - 35 sec’s -Avoidance
- With TCAS when given a traffic advisory what would the pilots display indicate to him?
o A relative indication of a solid amber circle / the aircraft’s altitude / if it is climbing or descending (an arrow) and an aural “TRAFFIC TRAFFIC’
- What is GPS, how does it work, and how many satellites are required?
o The Global Positioning System is a satellite-based radio navigation system which can provide users with position and time information of tremendous accuracy, anywhere on the earth, 24 hrs a day, and in all weather.
o Position in space is determined by measuring dist from a group of satellites in space, much like a DME fix but in 3 dimensions not 2.
o 4 minimum
- What is differential GPS?
o Using ground based receivers at a known location to calculate error in the satellite data they then send other receivers (aircraft) an error correction message. Which in turncorrect themselves, computing a more ‘relative position between an aircraft receiver and a ground based receiver for them to track to.
- Multi channel receivers are able to do what?
o Assign and lock onto individual satellites per channel enabling them to track and compute the most accurate position using the best satellites. Reducing the GDOP effect
- What is GDOP?
o Geometry dilution of precision – the angle of the satellites relative to the aircraft, larger angles provide better accuracy of position and distance.
- What is ADS?
o ADS is Automatic dependant surveillance – the ability to track aircraft using GPS position information which is automatically fed to ATC via the aircraft avionics. This will assist in reduced separation, least fuel tracks,
o ADS communication will also effectively relieve the need for voice communication.
- Explain FANS.
Future Air Navigation System – Implementation of satellite technology for improved communication and navigation tracking surveillance.
It is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting.
- Explain ETOPS.
o ETOPS stands for Extended Range Twin Engine Operations and is the term used to govern regulations and procedures pertinent to twin engine commercial aircraft operating on extended global or domestic routes with poor off track alternates. The basic premise regarding this topic is related to the concept of redundancy and failures of the powerplant,/hull. The basis of ETOPS is the improved engine reliability shown by new age aircraft.
o The rules state that any aircraft with two engines must be capable of flying to an adequate airport where it can land safely within 90 minutes at normal cruise speed or 60 minutes at single engine cruise speed (in still air conditions). If the aircraft can not comply with the above regulation – it is then required to become an ETOPS rated aircraft.
o With an ETOPS rating, this rule is extended up to 90mins, 120mins, 138mins and 180mins.
o Individual aircraft must be specifically authorised. As new aircraft are introduced to the fleet a proving period is implemented at 120 min before a higher classification is considered.
o Air New Zealand currently operates B777 on 330 min ETOPS. However when suitable alternates exist it for 120 min ETOPS it may be advantageous to operate to this criteria as opposed to 180 min. These advantages are in the area of MEL dispatch and minimum fuel reserves to be carried.
o The ETOPS times stipulated simply determine the single engine time in still air from which an aircraft must remain from a suitable alternate.
- Explain Great Circle.
o A circle drawn on the face of the earth whose radius is the earth. Its plane passes through the centre of the earth. It is the shortest distance between two places.
- Explain Small Circle.
o Any circle drawn on the earth whose radius is not the earth. Its plane does not pass through the centre of the earth.
- Explain Rhumb line.
o A line drawn on the centre of the earth which cuts each meridian at the same angle.
- Explain Parallel’s of Latitude.
o Small circles joining points of equal latitude – except equator, which is a great circle
o All are rhumb lines
o Lie east to west
- Explain Meridian’s of Longitude.
o Semi-great circles passing thru the poles.
- What is Prime Meridian?
o A semi-greatcircle passing through the poles and also Greenwich. Known as the Greenwich meridian. It defines a longitude of zero degrees.
o 0000UTC is said to exist when the sun is directly over head the anti meridian (180)
- What is an Isogonal?
o Line joining points of equal variation
- Define Nautical Mile.
o Distance on the surface of the earth which subtends an angle of one minute of arc at the centre of the earth
o 6080 ft
o One degree of change of latitude along a meridian represents a distance of 60nm (60min of arc)
- What is departure formula?
o Necessary due to the fact that 1 degree of longitude is only equal to 60nm at the equator. Any deviation from the equator needs reference to the departure formula. o Distance (nm) = change of long(in mins of arc) x cos lat
- Explain Earth Convergency.
o The angle of inclination between two meridians at any given latitude
o Earth convergency = change in long x sin mean lat
- What is the rotation of Earth?
o 900kts at equator, or
o 900 x Cos Lat = speed at a given latitude
- Explain Mercator Projection?
o Cylindrical projection
o All meridians appear as straight lines with parallel spacing
o All parallels are straight lines with the distance between them increasing with increase in latitude
o Poles are unable to be projected
o Lat and long intersect at right angles
o A Rhumb line will appear as a straight line
o A great circle will appear as a curved line concave to the equator
- Explain Lambert Projection
o This utilises a conical projection with the apex of the cone directly above the pole
o Meridians appear as straight lines converging towards the pole
o Parallels appear as straight lines with the distance between them being constant
o Lats and Longs intersect at right angles
o Rumb lines appear as curved lines concave to the nearest pole
o Great circles appear as straight lines (in fact the are very slightly curved toward the parallel of origin.
