Important Questions For AAI ATC Interview | Article 5/5

It’s the 5th and final article of the exclusive AAI ATC Interview Series which primarily focuses on the preparation of the JE (ATC) Interview. The series consists of Five Articles that cover non-technical as well technical questions that I suppose can be asked in the ATC interview.

This article covers some important topics which could not be included in other articles. Some of the topics are radio wave propagation, Line of sight, antenna, duplexer, etc.

Ques. 53: What is Antenna?

Ans. An antenna is an electrical device used to convert electrical signals to radio waves and vice versa. A basic antenna has two parts i.e. Transmitter and Receiver.

Ques. 54: What is Duplexer?

Ans. A duplexer is a device used in communication systems that can eliminate the need for a separate transmitter and receiver antenna. It alternatively switches the single antenna between transmitter and receiver. The duplexer also prevents high-power transmitted pulses to enter the receiver as it might destroy the receiver which is highly power-sensitive device.

Ques. 55: What is ADS-B?

Ans. ADS-B is an acronym for Automatic Dependent Surveillance-Broadcast.ADS-B system uses transmissions from aircraft to provide geographical position, pressure altitude data, positional integrity measures, flight identity, 24-bit aircraft address, velocity, and other data which have been determined by airborne sensors.

Ques. 56: How does Aircraft establish a connection with ATC?

Ans. It is done through VHF or HF communication. Usually, the communication takes place in the VHF band only but in areas like oceans where it is not possible to install navigation equipment, HF communication plays a vital role to establish a connection between ATC and Aircraft.

Ques. 57: How do radio waves propagate?radio wave propagation

Ans. Radio Waves can travel through one of these methods:

  1. LOS (Line of Site): Limited communication area
  2. Sky-wave Propagation: can cover the entire globe.
  3. Ground-wave Propagation: range in between Mode 1 & 2.

Ques. 58: What is the Line of Sight propagation?

Ans. It is the simplest form of propagation. In LOS mode, the Distance between the transmline of sightpropagationitter and receiver is dependent
on the frequency/wavelength of the signal.  Line of site propagation is very useful at VHF and UHF Frequencies. The range of LOS communication depends on the height of the Transmitter.

Ques. 59: What is a critical frequency?

Ans. In Sky wave propagation, Critical frequency is the limiting frequency at or below which wave is reflected back from the ionosphere, above critical frequency the wave penetrates the ionosphere and never comes back. So for sky wave propagation the value of frequency f≤ fc .

Ques. 60: What are different frequency bands?

Ans. Frequency bands are shown in this table. The corresponding wavelength can also be calculated by the formula: wavelength= c/ffrequency bands

Ques. 61: In which frequency band ATC communication takes place?

Ans. VHF Band: Generally Pilot-ATC Communication takes place in this band. However, sometimes HF Band is used as well for long-range communication where VHF communication is not possible. You must know that with the increase in frequency, the Range of communication gets decreased.

Ques. 62: What is Mach Number?

Ans. Mach number is a common term used in the Aviation world that denotes the ratio of air speed to the local speed of sound, e.g. Mach 1 denotes the speed equal to the speed of sound.

Ques. 63: What is Supersonic aircraft?

Ans. A supersonic aircraft is an aircraft that can exceed the speed of sound (Mach 1.0) in level flight. (Level flight means when aircraft is moving at a fixed altitude i.e. not climbing or descending). Concorde was a supersonic aircraft.

Ques. 64: Why uplink and downlink frequencies are different for Satellite or Mobile communication?

Ans. Uplink (fu) and Downlink frequencies (fd) are different so that there is no interference. Remember that in satellite communication: fu>fd whereas in Mobile Communication fd>fu.

The reason is higher the frequency, the higher will be the energy requirement.

Ques. 65: What is the speed of sound?

Ans. The speed of sound varies with the temperature. The speed is proportional to the square root of the absolute temperature, giving an increase of about 0.6 m/s per degree Celsius. Some values are: 340m/s at Sea Level (Temp. 15 C), 331m/s at 0 C.

Also Read: Important Terms and Definitions for JE-ATC Interview

Don’t forget to share it if you find it useful.


Did You Find This Post Useful?

Subscribe Below And Get Such Posts into Your Inbox

About The Author

4 thoughts on “Important Questions For AAI ATC Interview | Article 5/5”

  1. Ruptalyn Ingtipi

    Sir how do we check marks for advt no. 07/2015,exam held on 24th april 2016…i followed your link above but didn find any marks recorded.
    Also my application has ex-serviceman option 2 written which id did not understand.
    Is there any error from my end there?

Leave a Comment

Your email address will not be published. Required fields are marked *

Share via
Copy link
Powered by Social Snap