Correct Answer : Reduced visibility
Explanation : Considerable interference to civil and military operations results due to reduced visibility in terminal areas. While the successful landing of aircraft depends on many factors other than visibility and ceiling, such as cross winds and storm activity, the term all weather operations often refers only to operations in conditions of reduced visibility.
Correct Answer : Instrument meteorological conditions
Explanation : Instrument meteorological conditions or IMC are those in which visibility is restricted to various degrees defined by law in certain countries. Aircraft operating in IMC are supposed to fly under instrument flight rules also defined by law.
Correct Answer : Decision height
Explanation : During a landing, the decision height or DH is the height above the runway at which the landing must be aborted if the runway is not in sight. Usually, with better avionic systems and electronic aids, the DH can be lowered.
Correct Answer : 200ft
Explanation : The decision height for category I systems is not less than 200ft, visibility not less than 2600ft, or runway visual range not less than 1800ft with appropriate runway lighting.
Correct Answer : 5-10%
Explanation : Since during a flare maneuver the angle of attack is increased both lift and drag is increased. The excess lift causes upward acceleration to reduce the rate of descent and the increase in drag accounts for the reduction in the speed of the aircraft.
Correct Answer : 3ft/sec
Explanation : Land based aircraft are not designed to touch down at the 6 to 16ft/sec sink rate that exists along the glide path. Thus, a flare maneuver must be executed to reduce the descent rate to less than 3ft/sec at touchdown.
Correct Answer : 250 to 1000ft
Explanation : For non precision approach, the minimum descent altitude is defined below which the aircraft may not descend without visual contact with the runway. It ranges from 250 to 1000ft depending upon local obstructions, aircraft type, navigational aids and runway lighting.
Correct Answer : Pitch, roll and azimuth cues
Explanation : The light bars provide azimuth, roll and pitch cues to the pilot. Center line and edge lights provide rollout cues.
Correct Answer : Ceilometers
Explanation : Ceilometers and transmissometers are used to measure terminal area visible conditions. These measures visible conditions differ from each airport and due to weather. During each approach, these data radioed to the pilot.
Correct Answer : Head up display
Explanation : In a category II system the aircraft must carry dual ILS receivers, dual flight directors, two pilots, radar altimeter, rain removal equipment and missed approach attitude guidance. Auto throttle system may also be required.
Correct Answer : Category III C
Explanation : Category III C is the system’s ability to fly under zero visibility conditions. It has no DH and RVR limits.
Correct Answer : Alert height
Explanation : Alert height is the altitude below which landing may continue in case of equipment failure. To meet alert height restrictions, either the avionics must be fault tolerant or the crew must be able to take over manually.
Correct Answer : Category II
Explanation : Air carrier aircraft that are authorized for precision approach below Category II must have an automatic landing system. Auto land systems use information from various landing systems like ILS Tacan and at some cases even GPS to safely land the aircraft.
Correct Answer : Gain scheduling
Explanation : During the final approach the glide slope gain in the auto land system is reduced in a programmed fashion and is called gain scheduling. Supplementary sensors must supply the vertical guidance below 100ft.
Correct Answer : 1.5 ft
Explanation : Low range radar altimeters have a nominal accuracy of 1.5 ft below 100ft altitude and 2% of full scale at higher altitude. They have a low noise output that allows the derivation of vertical rate information.
Correct Answer : 75ft
Explanation : The flare command is initiated at a wheel height of about 75ft, well before the runway threshold. However, the radar altimeter may not be used prior to threshold due to uneven terrain or tidal variations.
Explanation : The localizer gain must be scheduled to decrease as the runway is approached because the surfaces of constant DDM coverage to make the error signal more sensitive to distant displacement.
Correct Answer : ILS
Explanation : The instrument landing system or ILS is a collection of radio transmitting stations used to guide aircraft to a specific airport runway, especially during times of limited visibility.
Correct Answer : Depends upon density of traffic on the airspace
Explanation : High density airports where a lots of planes land and take off typically have more than one runways with multiple ILS systems. Chicago’s O’Hare airport had an ILS installed on 12 runways in 1996.
Correct Answer : ICAO standards and recommended practices
Explanation : The ICAO Standards and Recommended Practices for the ILS, subscribed by the180 member states, standardize the signal in space for the ILS ground transmitting equipment, no matter where they are manufactured to maintain international standards.
Correct Answer : 75 MHz
Explanation : All the marker beacons, all around the world, operate on a single frequency of 75MHz.
Correct Answer : Horizontal polarization
Explanation : Every transmitter in the ILS including the glide slope transmitter, localizer and the marker beacons radiate continuous wave, horizontally polarized, radio frequency energy which can be received by the on-board receiver.
Correct Answer : Radiation monitors
Explanation : Radiation monitors are used to detect ILS failure. They are placed at a particular distance away from the runway to check for errors in ILS transmission or drift in the frequency of radiation.
Correct Answer : Beyond the stop end of the runway
Explanation : The localizer antenna is centered on the runway beyond the stop end to provide lateral guidance. The glide slope is located beside the runway near the threshold to provide vertical guidance.
Correct Answer : Crystal controlled
Explanation : The marker beacon receiver is a dedicated crystal controlled receiver fixed tuned to 75 MHz. This is because all marker beacons use the same frequency.
Correct Answer : Ground reflection
Explanation : Mulit path Signals are created when a part of the original signal take a different path than LOS to reach the receiver. Thus a signal with same information reaches the receiver at multiple times. Multi path signals are created when the actual signal gets reflected from the ground and reaches the receiver.
Correct Answer : Localizer
Explanation : An audible Morse code identification signal is transmitted on the localizer frequency. A voice channel from the control tower may also be provided.
Correct Answer : Fan shape
Explanation : Marker beacons provide pilot alerts along the approach path. Each beacon radiates a fan shaped vertical beam that is approximately ±40° wide along the glide path by ±85° wide perpendicular to the path.
Correct Answer : Image glide slope
Explanation : Image array glide slope systems depend on reflections from the ground in the direction of approaching aircraft to form the radiation pattern.
Correct Answer : Long periodic antenna
Explanation : Almost all of the localizer antenna is long periodic antenna. It provides unidirectional radiation, can be installed without guy cables and has good broadband characteristics.
Correct Answer : Clearance signal
Explanation : When the localizer CSB pattern is narrow, to reduce reflections from buildings and other aircraft, the system requires the addition of “clearance” signals to provide 35° coverage in both directions.
Explanation : The localizer establishes a radiation pattern in space the provides a deviation signal in the aircraft when the aircraft is displaced laterally from the vertical plane containing the runway center line.
Correct Answer : Environment sensitivity
Explanation : The main weakness of the ILS system was its sensitivity towards the environmental factors. Since the frequency used by the system is in MHz, it was more susceptible to atmospheric and weather interference.
Correct Answer : Bit error rate
Explanation : The acceptable bit error rate of the differential phase shift keying (DPSK) transmissions at the 20-nmi limit determines the transmitter power needed in the ground stations.
Correct Answer : 200
Explanation : The MLS station transmit both angle and data functions on one of 200 frequencies between 5031.0 and 5190.7 MHz. The relatively high number of channels allows the use of multiple MLS in metropolitan cities.
Correct Answer : Narrow beam width antennas
Explanation : The main weakness of the ILS system is eliminated by using narrow beam width antennas which are physically small since the frequency is high. As frequency increases antenna size decreases.
Correct Answer : Radar
Explanation : A basic MLS consists of azimuth and elevation ground stations and a conventional DME for 3D positioning on approach course to 40° on either side of center line and to 15° elevation above the runway.
Correct Answer : Missed approach
Explanation : An expanded MLS system uses back azimuth stations. It is generally used for departure and for missed approaches. It provides lateral guidance to 40° on either side of the center line.
Correct Answer : Number of users
Explanation : The primary reason for not using basic GPS for landing systems is because does not provide the accuracy that is required for landing, it lacks a monitoring system and the availability of a sufficient number of satellites to provide location information.
Correct Answer : WAAS
Explanation : For non-precision and Category I precision approaches, the limitations by the GPS is mitigated by the FAA’s Wide Area Augmentation System. It may be supplemented with local differential GPS stations located near runways.
Correct Answer : Provide precision approaches for Category III C
Explanation : WAAS addresses the limitations by providing Wide area differential GPS error correction, a ground integrity broadcast, and a GPS ranging function from three or four geostationary satellites providing additional availability.
Correct Answer : Multi-path signal interference
Explanation : LDGPS operation leads to the nearly complete cancellation of errors due to satellite ephemerides, clock offset, selective availability, and ionospheric propagation, leaving mainly those errors due to multipath signal interference and receiver noise.
Correct Answer : High- integrity ground to air data link
Explanation : To support Category II and III landing operations, the additional requirement for accuracy and monitor-response times can be achieved with a differential GPD reference station and a high-integrity ground to air data link located near the runway.
Correct Answer : Lower
Explanation : Jet aircraft approach the carrier deck with at airspeeds up to 125 knots. Their speed relative to the deck is lower due to the “wind over the deck,” which is normally about 30 knots.
Correct Answer : 4°
Explanation : The approach path, often called the glide slope, is in the vertical plane containing the runway center line and is inclined 3.5° relative to the sea at the touchdown point and 4° relative to the moving flight deck.
Correct Answer : Steady state wake
Explanation : Steady state wake caused by the relative wind over the ship’s deck and around the superstructure, Which causes a “burble” at the threshold and the glide path.
Correct Answer : Heaving motion of ship
Explanation : Wake perturbations, due to the ship’s angular motions and heave, causing fluctuations with standard deviations of 2 ft/sec(horizontal) and 4 ft/sec (vertical) about the steady state wake.
Correct Answer : Bolter
Explanation : An aircraft executing a missed approach from low altitude is called a bolter. Bolters fly to a Tacan- defined holding point that moves with the aircraft carrier.
Correct Answer : Aircraft beacon
Explanation : The SPN-42 was retrofitted with a small X-band parabola when aircraft beacons were added to eliminate errors caused by wandering of the echo skin.
Correct Answer : Only handle one aircraft at a time
Explanation : The two identical conically scanned radar antennas can track two aircraft simultaneously and, if desired, can uplink guidance signals to autopilots.
Correct Answer : Ka band
Explanation : Two electronic instrument landing systems are found o all large U.S. carriers. Th ACLS involves two identical conically scanned Ka band radars set aft of the island about 125 and 135ft above the water line.
Correct Answer : FLOLS
Explanation : FLOLS or the Fresnel lens optical landing system consists of an array of 5 Fresnel lens showing the pilot a yellow spot that moves relatively to a lighted green horizontal reference bar.
Correct Answer : Two aircraft use simultaneously
Explanation : Lens pointing angles can be adjusted to a quadratic function of heave and can be compensated. This compensation is not implemented because the “meatball” is often shared by two aircraft on final approach simultaneously.
Correct Answer : Air traffic control and traffic flow management
Explanation : The purpose of air traffic management is safe, efficient, and expeditious movement of the aircraft in the airspace. Its two major principles are air traffic control and traffic flow management.
Correct Answer : ATM
Explanation : The primary service provided by ATM is separation assurance for the prevention of collisions between aircraft and to prevent aircraft collisions with terrain and obstructions.
Correct Answer : ICAO
Explanation : Standardization of the air traffic management practices internationally is the responsibility of the International Civil Aviation Organization or IACO, which is affiliated with the United Nations and located in Montreal, Quebec, Canada.
Correct Answer : Flight technical error
Explanation : Flight technical error is the lateral displacement error of the aircraft from the intended track given the course deviation error signal generated by the navigation system.
Correct Answer : 54,000ft
Explanation : Pressure altitudes are expressed as flight levels on hundreds of feet using three digits. Hence, FL540 represents a pressure altitude of 54,000 ft.
Correct Answer : One statute mile
Explanation : VFR operators below 10,000ft MSL must have a minimum visibility of one statute mile. VFR operators are not required to contact ATM in the controlled or uncontrolled airspace.
Correct Answer : VFR operator
Explanation : Visual Flight Rules operator are responsible for avoiding collisions with obstacles, terrain and other aircraft by visually observing these hazards and maintaining visual separations. VFR operators are not required to contact ATM authorities and are not subject to their directions.
Correct Answer : ATM operator
Explanation : In controlled airspace, the crew must operate in accordance with instructions received from ATM authorities, and these authorities are responsible for separating the aircraft from all other IFR aircraft.
Correct Answer : VFR
Explanation : VFR flights usually involve small aircraft operated for personal or business purposes. Navigation may be by visual reference to the ground and aircraft attitude control may be based solely on the natural horizon visible through the windscreen of the aircraft.
