Airports India - - NEWS -

The air fly­ing routes and pro­ce­dures are de­signed by tak­ing the dis­tance, fuel con­sump­tion, safety and area of Com­mu­ni­ca­tion, Nav­i­ga­tional and Sur­veil­lance (CNS) fa­cil­i­ties in mind. Fur­ther, it’s a chal­lenge for the Air Nav­i­ga­tion Ser­vices (ANS) provider to in­stall the CNS fa­cil­i­ties at a suitable lo­ca­tion/site from where it can serve its pur­pose as per the guid­ance of In­ter­na­tional Civil Aviation Or­ga­ni­za­tion (ICAO). The chal­lenge of site se­lec­tion is al­ways a dif­fi­cult job for CNS En­gi­neers. The lo­ca­tion, ter­rain con­di­tions, ap­proach roads avail­abil­ity and other fa­cil­i­ties re­quired for the smooth op­er­a­tion of such fa­cil­i­ties are most im­por­tant con­sid­er­a­tions in site se­lec­tion. And the most dif­fi­cult con­di­tion is the task to find out the best site on the ba­sis of ter­rain con­di­tions from cov­er­age as well as multi-path in­ter­fer­ence point of view.

The CNS field ex­perts of Air­ports Au­thor­ity of In­dia used to visit the pro­posed sites, con­duct the sur­vey, make man­ual cal­cu­la­tions and se­lect the site on the ba­sis of sev­eral site se­lec­tion pa­ram­e­ters. Due to the man­ual tech­niques, it was time-con­sum­ing and of­ten in­nacu­rate. In to­day’s tech­no­log­i­cally ad­vanced times, sev­eral nu­mer­i­cal meth­ods are be­ing used in the world for the job of site se­lec­tion for in­stalling CNS fa­cil­i­ties for im­proved air nav­i­ga­tion. Tech­niques de­ployed to em­u­late real-time con­di­tions and the en­vi­ron­ment are a part of sim­u­la­tion, and the tools used for the same are called Sim­u­la­tors. One such sim­u­la­tor used by AAI’S CNS en­gi­neers is EMACS (Elec­tro Mag­netic Air­port Con­trol and Sur­vey).

Why are sim­u­la­tion tech­niques re­quired?

The world is wit­ness­ing rapid growth in the aviation sec­tor and to cope up with this fast-paced growth, AAI, as a lead­ing air­port op­er­a­tor and air nav­i­ga­tion ser­vice provider re­quires fast, ac­cu­rate and ad­vanced tools for the job of sim­u­la­tion. EMACS is an ad­vanced tool for the job of Ra­dio Con­verge and Sig­nal Anal­y­sis as­sess­ment of CNS fa­cil­i­ties. It has the site se­lec­tion ca­pa­bil­ity and can also as­sess the im­pact of ex­ist­ing and fu­ture de­vel­op­ments of air­port in­fra­struc­ture on the ex­ist­ing CNS en­vi­ron­ment.


The Aero­nau­ti­cal In­for­ma­tion Ser­vices (AIS) Au­to­ma­tion sys­tem of AAI is an in­te­grated sys­tem used for the CNS sim­ula-

tions, AIS Pub­li­ca­tion, Flight pro­ce­dure design and Airspace Man­age­ment, which is in­stalled at the AAI Head­quar­ters. To com­plete all these ac­tiv­i­ties, the sys­tem has three com­po­nents with a com­mon data­base. EMACS - (Elec­tro Mag­netic Air­port Con­trol Sur­vey) Aeropub - (AIS Pub­lisher) FPDAM - (Flight Pro­ce­dure Design and Man­age­ment) One of the ma­jor and most im­por­tant com­po­nents of this sys­tem is EMACS. This sys­tem is be­ing utilised for the CNS sim­u­la­tion stud­ies to find out the im­pact of ex­ist­ing as well as pro­posed struc­tures, site se­lec­tion and in­ter­fer­ence as­sess­ment of CNS fa­cil­i­ties etc.


EMACS is a set of val­i­dated elec­tro­mag­netic 3D-mod­el­ling and sim­u­la­tion tools, ca­pa­ble of cop­ing with EMC (Elec­tro Mag­netic Com­pat­i­bil­ity) is­sues and EMI (Elec­tro Mag­netic In­ter­fer­ence) prob­lems in Air­port and Air Nav­i­ga­tion site sce­nar­ios. The mod­el­ling func­tion­al­ity (in­clud­ing ter­rain mod­els, ob­sta­cles, in­ter­fer­ing sys­tem, ground and air­borne Nav-aid equip­ment char­ac­ter­is­tics etc.) al­lows an ex­pert user to model the real prop­a­ga­tion phe­nom­ena tak­ing place within a com­plex Elec­tro Mag­netic Air­port sce­nario, where ra­dio nav­i­ga­tion sig­nals in­ter­fere with ar­ti­fi­cial or nat­u­ral ob­struc­tions or other EM Sys­tems.

How does it work?

Ba­si­cally EMACS is a tool based on the most so­phis­ti­cated and widely known com­pu­ta­tional elec­tro­mag­netic tech­niques.

The EMACS soft­ware has two el­e­ments, Mi­cro­sta­tion (CAD soft­ware) used to draw or to cre­ate the 3D Com­puter Model of an Air­port In­fra­struc­ture Sce­nario which in­cludes the ob­sta­cles and CNS fa­cil­i­ties. Sec­ond, is the Elec­tro­mag­netic En­vi­ron­ment ap­pli­ca­tion which is an ap­pli­ca­tion tool for the place­ment and mod­el­ling of An­ten­nas (of a par­tic­u­lar CNS fa­cil­ity), this struc­ture is used in sim­u­la­tion. Both the ap­pli­ca­tions work like an Air­port, where, all the NAV-AID fa­cil­i­ties are in­stalled and are sur­rounded by the air­port in­fra­struc­ture like Ter­mi­nal Build­ing, Tower, Cargo Build­ing etc.


SRTM1 ter­rain data of 900M and 90M res­o­lu­tion is used for the ter­rain el­e­va­tion ac­tiv­i­ties.

The same data is used for the Ra­dio Cov­er­age anal­y­sis and Sig­nal Anal­y­sis. The sys­tem has a very pow­er­ful tool for ter­rain man­age­ment. This can be used for the as­sess­ment of ter­rain in a very typ­i­cal area which is very dif­fi­cult to reach for tak­ing the mea­sure­ment of el­e­va­tion points/slopes and other things re­lated to it. This tool is used to find out the min­i­mum op­er­a­tive ser­vice vol­ume of In­stru­ment Land­ing Sys­tem (ILS). The sys­tem is very use­ful for very dif­fi­cult ter­rain en­vi­ron­ments, es­pe­cially for coun­tries like In­dia.

TYPE OF SIM­U­LA­TION ANAL­Y­SIS Ra­dio Cov­er­age Anal­y­sis

The Ra­dio Cov­er­age of a par­tic­u­lar fa­cil­ity is sim­u­lated for the im­pact as­sess­ment of the sur­round­ing ter­rain, en­vi­ron­ment and man-made ob­sta­cles. The ap­pli­ca­tion is a very use­ful tool to anal­yse the im­pact of pro­posed struc­tures by com­puter mod­el­ling. Gen­er­ally, the Ra­dio Cov­er­age sim­u­la­tion is done to find out the best suitable site

for the in­stal­la­tion.

Sig­nal Anal­y­sis

The sig­nal anal­y­sis is ba­si­cally done to sim­u­late the ex­pected multi-path ef­fect of Ra­dio Sig­nals and their im­pact on the CNS fa­cil­ity.

As of now, with the in­creas­ing de­mand to build or con­struct the in­fra­struc­ture of air­ports like New Ter­mi­nal build­ings, Cargo com­plexes, ATC Tower-cum-tech­ni­cal Blocks and also the com­mer­cial struc­tures like ho­tels etc., the CNS fa­cil­i­ties are be­ing af­fected. The re­sults of the sim­u­la­tions are very sim­i­lar to the flight in­spec­tion; this refers to the pe­ri­odic eval­u­a­tion of nav­i­ga­tional aids used in aviation, such as flight pro­ce­dures and elec­tronic sig­nals, to en­sure they are safe and ac­cu­rate.

AP­PLI­CA­TION OF EMACS Site Se­lec­tion

The main ap­pli­ca­tion of EMACS is for the im­pact as­sess­ment of ex­ist­ing as well as pro­posed in­fra­struc­tures. The ATC tow­er­cum-tech­ni­cal Block and In­te­grated Ter­mi­nal Build­ings are the main projects and their pro­posed height is re­stricted by Lo­cal­izer, VOR2, ASR/MSSR3, INRES4 etc. In the case of such height re­stric­tions, the mat­ter is used to ex­am­ine by CNS for sim­u­la­tion study as per the pro­vi­sions of GSR-751(E) (laid down Rules of the Min­istry of Civil Aviation).

The goal: Elec­tro­mag­netic mod­el­ing and sim­u­la­tion of ra­dio nav­i­ga­tion

EMI In­ter­fer­ence

In the elec­tro­mag­netic en­vi­ron­ment, there is the pos­si­bil­ity that one Trans­mit­ter may af­fect the Trans­mit­ter/re­ceiver of a dif­fer­ent fre­quency. We can say that one fre­quency may be the vic­tim of the other and this can cre­ate in­ter­fer­ence es­pe­cially in the case of VHF fre­quen­cies. The EMI tool of the EMACS is used to as­sess this type of in­ter­fer­ence.

Multi-ra­dio Cov­er­age sim­u­la­tion

To find the ra­dio cov­er­age gaps in be­tween more than two NAV-AIDS or sur­veil­lance sys­tems.

Wind Tur­bine sim­u­la­tion is used to anal­yse its ef­fect of VOR and SSR.


In the last 5-6 years, a num­ber of sim­u­la­tion stud­ies have been com­pleted suc­cess­fully, which in­cludes the issue of NOC (No Objection Cer­tifi­cate) of many Atc­tower-cum-tech­ni­cal Blocks, Ter­mi­nal build­ings, Cargo Com­plexes, Apron Flood Masts, VHF Masts, re­lo­ca­tion of CNS fa­cil­i­ties, Ho­tel Com­plexes, Chen­nai Metro Rail Cor­po­ra­tion study and fea­si­bil­ity study of Mumbai ILS. EMACS sys­tem has also been used for lo­cat­ing Ra­dio Cov­er­age Gap of NAV-AID and Sur­veil­lance over In­dian Airspace. Khusiyal Singh Sr. Man­ager (CNS), AAI


1. Shut­tle Radar To­po­graphic Mis­sion (SRTM) - It is an in­ter­na­tional re­search ef­fort that ob­tained digital el­e­va­tion mod­els on a near-global scale from 56° S to 60° N, to gen­er­ate the most com­plete high-res­o­lu­tion digital to­po­graphic data­base of Earth 2. Very High Fre­quency Omni-range (VOR) – a ra­dio nav­i­ga­tional aid 3. Air­port Sur­veil­lance Radar/monopulse Se­condary Sur­veil­lance RADAR (ASR/MSSR) 4. In­dian Ref­er­ence Sta­tion (INRES) – part of satel­lite based nav­i­ga­tion sys­tem GAGAN (GPS Aided Geo Aug­mented Nav­i­ga­tion)

Fig. 2: Air­craft un­der the guid­ance of CNS sys­tems at an Air­port also hav­ing mul­ti­path and EMI ef­fect.

Fig. 1: Main over­view of EMACS Sys­tem

Fig. 4: An Air­port sur­rounded by a dif­fi­cult ter­rain is the best ex­am­ple for Sim­u­la­tion

Fig. 3: An ex­am­ple of Ter­rain show­ing vis­i­bil­ity and Mul­ti­path ef­fect

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