Rule 39C

Add to Your Knowledge for RTR (A) part 2

ADD TO YOUR KNOWLEDGE FOR PART-II ( Some more questions from the question bank answered)

UTC is a atomic clock time and GMT is a time maintained as per the rotation of the earth with respect to sun.
GMT- is maintained by royal observatory in Greenwich, London.
UTC- is maintained in Laboratories around the world.
The difference of UTC and GMT should not be more than 0.9 seconds and it is added to GMT at irregular interval and called Leap Seconds.
RESTRICTED AIRSPACE- The airspace within which flight of aircraft is restricted in accordance with certain specified conditions. This designation is normally used whenever the activities within
the airspace is hazardous to other users or other users could constitute a hazard to the activities carried out in that defined airspace as restricted.PROHIBITED AIRSPACE- An airspace within which flight of aircraft is not allowed, usually due to security concerns. It is depicted on on aeronautical charts with letter “P” followed by a serial no. It differs from restricted airspace in that entry is typically forbidden at all times for all aircraft and it is not subjected to clearance from ATC or Airspace controlling body.


A Phenomenon, observed for sound and electromagnetic radiation characterized by a change in the apparent frequency of a wave as a result of relative motion between the observer and the source.
(example- an apparent change in car horn when a car is in -motion with respect to stationary observer)


ELT- EMERGENCY LOCATOR TRANSMITTERS(ELT works on frequency 121 mhz, 121.5 mhz, 406mhz and 243 mhz)

working of ELT -1. After Aircraft crash>>>
2. Signals transmitted by ELT on 121mhz, 121.5mhz, 243mhz & 406mhz>>>
3. Signals picked up by polar orbiting any one of the 6 satellites>>>
4. Satellite in turn, relays the same location information of crashed aircraft to a ground station called “Local User Terminal – (LUT)” which has been established at Bangalore & also established in Lucknow, India>>>
5. LUT indicates the position of the active becon site radius of 5nm>>>relays it to – “Mission Control Center (MCC)” which is co-located with LUT, Bangalore>>>
6. MCC processes the Information, Identifies the Concerned FIR`s and automatically transmits the same to one of the 5 RCC(Rescue Co-ordination Center of 5 FIR`s) by Telex.

Facts about ELT:

* In case of Aircraft crashes in foreign>> MCC receives Data from Foreign LUT and relays it to Indian RCC.
* To identify where there crashed Transmission is from Ship or Aircraft which cannot be detected by LUT & MCC, if ship/aircraft uses freq. 121.5 mhz & 243 mhz but by using freq. 406 mhz they
get enough of data to identify the signal is from ship or aircraft. it also identify particular crashed ship or aircraft.

D-VOR (Dopplers VOR)

In dopplers VOR (2nd generation VOR) the reference signal is transmitted from a central aerial and it is amplitude modulated. The variable signal is transmitted from a system of 50 aerials encircling the central aerial and it is frequency modulated. The signals send by VOR is of 30 Hz used for measuring phase difference. Doppler VOR is improved version of VOR, the resultant propagation is much less sensitive to obstructions in the vicinity.

(In conventional VOR, the variable signal is emitted by rotating it with 30 Revolutions per second. It carries a 9960 Hz sub-carrier that is frequency modulated at 30 Hz )

( C-VOR suffers from reflections from objects in the vicinity of the VOR site and found that errors were due to this could have been reduced if the horizontal antenna dimensions were increased)

*(In D-VOR the reference signal is amplitude modulated, while the variable signal is frequency modulated. This means the modulation is opposite as compared to C-VOR. This is because the frequency modulated signal is less subject to interference than the amplitude modulated signal and therefore the received signals provides more accurate bearing determination )

Aerodrome Reference Point (ARP)
Aerodrome Reference Point is Designated geographical location of an aerodrome given to the nearest second of latitude and longitude. The ARP is located as near as it is practical to the geometric center of the Landing area, taking into account of the possible future development of that area. Magnetic bearings and distance of obstructions within 4nm which may constitute hazards to 
aircrafts flying in vicinity of aerodrome are measured from ARP, also called Airport reference point.
Radio Telephony Reading Material

Cessna 172

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