This set of Aircraft Maintenance Question Bank focuses on “Aviation Communication Systems – ILS-2”.
1. What are the maximum number of channels in an instrument landing system?
Explanation: There can be a maximum of 40 channels in an Instrument Landing System. The channels are alternatively modulated at 90 Hz and 150 Hz. Signals from these channels are transmitted by means of co-located antennas.
2. What is the full form of IGS?
a) Instrument guiding system
b) Instrument guidance system
c) Instrument gauge system
d) Instrument gate system
Explanation: IGS refers to Instrument guidance system. It is a modified ILS used to accommodate a non-straight approach. A famous example for the IGS is approach to runway 13 at Hong Kong Kai Tak Airport.
3. Marker beacons operate at a carrier frequency of ________
a) 75 MHz
b) 75 Hz
c) 750 MHz
d) 75 Hz
Explanation: The marker beacons operate at a carrier frequency of 75 MHz. The beacons transmit signals which in turn activate an indicator on the flight deck instrument panel. This further enables the pilot to hear the tone of the beacon.
4. Which of the following instrument is used in CATII and CATIII approaches to determine decision height?
c) Radar altimeter
d) Radio altimeter
Explanation: The radar altimeter instrument is used in CATII and CATIII approaches to determine the decision height of an aircraft. In contrary, the CATI approach relies solely on altimeter indications.
5. CATIII localizers must cut off within __________ seconds of detecting an error.
Explanation: CATIII localizers must cut off within 2 seconds of detecting an error. On the other hand, CATI localizers may cut off within 10 seconds of detecting an error. Higher CAT categories involve shorter cut off times.
6. Generally, an aircraft is established by at least __________ prior to the final approach.
a) 2 nautical miles
b) 10 nautical miles
c) 8 nautical miles
d) 200 nautical miles
Explanation: Generally, an aircraft is established by at least 2 nautical miles prior to the final approach. At a controlled airport, ATC will direct the aircraft to the localizer course via certain assigned headings.
7. ALS is a mandatory requirement to perform CATIII landing operations.
Explanation: True, ALS is a mandatory requirement to perform CATIII landing operations. Further, the systems should also have sufficient capability and reliability in order to control the aircraft for a safe landing.
8. When was the first landing of a scheduled passenger airliner using ILS, in the U.S?
a) 26 January 1958
b) 26 January 1938
c) 26 January 1998
d) 26 January 2008
Explanation: It was on 26 January 1938, that a scheduled passenger airliner landed using the instrument landing system for the first time ever, in the United States of America. The flight was operated by the Pennsylvania Central Airlines.
9. The Wide Area Augmentation System provides precision guidance to __________ standards.
a) Category IIIIB
b) Category IIIA
c) Category II
d) Category I
Explanation: The Wide Area Augmentation System provides precision guidance to Category I standards. The Local Area Augmentation System is under development to provide guidance for Category III minimums or lower.
10. The first Category III Microwave Landing System for civil aviation was commissioned at Stansted airport.
Explanation: False, the first Category III Microwave Landing System for civil aviation was commissioned at Heathrow airport. It was commissioned in March 2009 and removed from service in 2017.
Sanfoundry Global Education & Learning Series – Aircraft Maintenance.
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