Small airports to be 1st to rely on GAGAN satnav for landings, at major Indian airports it would to be the second choice


Aircraft ordered by IndiGo and Air India final yr —a complete of 970 Boeing and Airbus planes—will come fitted with receivers that may seize ‘augmented satellite signals’ and thus perform an strategy and touchdown with none assist from ground-based navigation aids. Unlike the Global Navigation Satellite System (GNSS) indicators comparable to the primary GPS indicators utilized by motorists, plane navigation, particularly in low-visibility circumstances calls for augmented GNSS.Augmentation makes the GNSS/GPS indicators dependable sufficient for plane navigation. Augmentation is completed by SBAS or satellite-based augmentation system of geosynchronous satellites that transfer with the Earth to keep above a sure area, that’s. India’s SBAS referred to as GAGAN, stands for GPS Aided Geo Augmented Navigation. GAGAN satellites take the primary GPS indicators and increase them to enhance its accuracy, integrity, availability, and continuity.
But India’s proximity to the equator has posed issues for its SBAS. Will ionospheric occasions influence the use of GAGAN by airline plane? Narayan Dhital, satellite tv for pc navigation engineer and air navigation professional at the Galileo Control Centre in Germany revealed a examine assessing the GAGAN companies for APV-I and APV-II (Approach Procedure with Vertical steering) throughout Indian airspace. His analysis targeted on important integrity parameters comparable to satellite tv for pc error bounds and ionospheric error bounds, offering essential insights into the reliability and accuracy of satellite tv for pc navigation techniques in difficult environments. Dhital spoke to

Manju V

about the findings of his examine.

What had been the salient findings of your GAGAN efficiency evaluation examine, particularly with respect to the system’s usability in finishing up GAGAN-enabled approaches in India by airways?

It has been lengthy mentioned in consultants conferences and aviation stakeholders assembly that equatorial areas pose extreme ionospheric challenges that hinder the exploitation of full advantages of GNSS based mostly flight procedures. As majority of Indian FIR falls underneath the core equatorial area, it is no surprise to discover out that the efficiency of GAGAN service shouldn’t be repeatedly assembly the APV-I requirement which is being met by counterpart WAAS and EGNOS, principally the vertical steering confidence requirement (ionospheric delay principally results the vertical accuracy of the GNSS). The GAGAN system has to repeatedly inflate the ionospheric error safety sure, day by day phenomenon of bigger ion contents round 2 PM native time and troublesome to predict phenomenon of enhanced ion contents triggered by photo voltaic actions.
The massive span of spatio-temporal variation of the vertical confidence sure displays a extreme problem to roll-out APV-I procedures all through Indian FIR. With the enhance in quantity reference stations used to generate the GAGAN corrections for satellite tv for pc orbits, satellite tv for pc clocks and ionospheric delays, such spatio-temporal variation can be decreased. The proposed plan by the GAGAN is to embody extra reference stations in the outer zone of the India geography. This will certainly convey advantages, which now we have to wait and see.

GAGAN is able to


RNP 0.1 plane procedures and APV-I to a big extent. But most crucially, the 99.99% availability shouldn’t be met for APV-I, not to mention APV-II. Also, the influence of ionospheric occasions on GAGAN is extra extreme than, say, on different SBAS techniques, given the higher ionospheric exercise in the equatorial area. Considering these components, how do you see the GAGAN system being utilized by airways in India in the close to future?

Given that the Indian aviation market has a promising forecast and the information earlier in 2023 concerning a big contract of 900 plus aircrafts with Airbus and Boeing, I nonetheless see gradual increment in the uptaking of GAGAN for flight procedures in the future. This will be largely pushed by the Dual Frequency Multi Constellation (DFMC) GAGAN strategy. In such an strategy, the above-mentioned important problem of the ionosphere is basically eradicated and therefore, the confidence in vertical steering is improved. The situation of ionospheric scintillation will nonetheless stay which is much more distinguished in the equatorial area. But scintillation, which is brought on by fast fluctuation in amplitude and part of indicators, impacts principally the continuity of the service. Otherwise, the DFMC will enable dependable APV-I companies. It is to be famous that, up till final yr, solely GPS was licensed by the ICAO for air navigation. Now, Galileo, which can also be a world constellation, has additionally been licensed, and the multi-constellation strategy is on the method.
Another essential use case of GAGAN is the help in direction of PBN implementation and ADS B implementation. The market is clearly there however it will transfer slowly (as all the time is the case with aviation, modifications usually are not simple in security important infrastructure).

Do you assume GAGAN-enabled approaches would largely be restricted to smaller non-metro airports that aren’t outfitted with ILS?

Definitely, the GAGAN approaches are greatest utilized in the smaller airports. In the bigger airports, the airways are working greater plane for lengthy haul flights. Reliability of easy operations comes first and the present ILS provides such a higher diploma of reliability which the GAGAN based mostly APV-I cannot provide.
In the bigger airports, the ILS are offering dependable companies even throughout the All Weather Operations (together with zero visibility). In such context, the uptake of satellite tv for pc navigation based mostly procedures can be foreseen in two methods:
a. a method for enterprise SBAS in such bigger airports is the site visitors move optimization (finally, value efficient…environmental pleasant) the place a CAT-I like strategy is flown. This has to be completed throughout the decreased photo voltaic cycle part and through very calm photo voltaic actions.
b. the uptake of Ground Based Augmentation System (GBAS-F) as an alternative of SBAS (regardless that DF largely reduces iono error, it cannot take away scintillation impact and therefore the continuity can’t be improved). And the GBAS-F has the potential to meet all climate operation upto CAT-III
The GAGAN system for the time being can be utilized by smaller aircrafts flying in the bigger airports and predominantly by aircrafts flying in regional airports. There are a plethora of advantages by way of operational value, upkeep value and environmental safety, when smaller airports implement GAGAN based mostly LNAV/VNAV and APV-I procedures. It has much more advantages in the mountainous areas and regional airports.
Other than that, the newer airports are clearly the fundamental enablers of GAGAN uptake. As is the case of African nations, the place A-SBAS can be promising for regional socio-economic growth, the GAGAN can present nice help to the UDAN-“Regional Connectivity Scheme” (RCS) being developed by the Government of India.
It is talked about in the reply to the earlier query as nicely that the mandate of ADSB in future might convey extra fleets to be GAGAN outfitted. Going ahead, the PBN plan additionally performs a important function.

Last yr, IndiGo carried out a trial through which an ATR plane carried out an LPV strategy at Kishangarh airport. The minima was 250 toes. Do you assume GAGAN system’s integrity efficiency meets the requirements to enable for such LPV approaches to be used on a daily foundation? If not, please clarify the components/circumstances that may restrict its use.

As talked about above, the usability of LPV is presently restricted due to the increased ionospheric actions in India. ICAO has advisable India to repeatedly monitor and consider the efficiency of ionospheric monitoring techniques. A steady evaluation of the efficiency is a primary step to have a plan for common LPV approaches. After that, if the efficiency requirement can be met, the design/validation of LVP flight procedures is essential. It took some whereas for India to collect competences in design and validation of SBAS procedures. That competence can now be used to pace up LPV implementation in different airports.

5) Airports in cities comparable to Mumbai, Delhi, Bangalore, Chennai, Kolkata, Kochi and many others are outfitted with ILS. How do you see GAGAN system being utilized in these airports?

As far as Mumbai airport is anxious, I imagine, an LNAV/VNAV strategy has been revealed by the Airports Authority of India. But LNAV/VNAV has the next minima than ILS CAT-1.

In the close to future then, do you see GAGAN techniques getting used to perform approaches in such metro airports?

Regarding the Mumbai airport, the LNAV/VNAV is revealed however not the LPV due to the terrain and impediment avoidance necessities. The fundamental distinction between LPV and LNAV/VNAV is the configuration of protected areas round the flight strategy path. If the geographical terrain permits, LPV based mostly procedures as an alternative of LNAV/VNAV can be carried out in any airports. LPV 250 is the most possible process if the DFMC GAGAN is realized. From a expertise standpoint, LNAV/VNAV and LPV procedures fall underneath the identical strategy methodology.
At these bigger airports, I see GAGAN procedures as a secondary navigation system to the established ILS. The newer plane that are SBAS outfitted can fly the GAGAN based mostly procedures throughout nominal ionospheric interval and doubtless throughout site visitors congestion interval. The smaller plane would possibly discover GAGAN based mostly strategy extra enticing by way of operational and upkeep value.
In abstract, I see an excellent prospect for GAGAN based mostly approaches in metro airports after the DFMC system comes into play. Until then, the regional airports and smaller aircrafts are the fundamental clients that may drive GAGAN additional.

(Narayan Dhital’s evaluation of GAGAN performances for non-precision plane strategy and touchdown was carried in the September 2023 situation of Coordinates, an unique month-to-month journal on positioning, navigation, related applied sciences and purposes.

Nilesh Desai
Nilesh Desai
The Hindu Patrika is founded in 2016 by Mr. Nilesh Desai. This website is providing news and information mainly related to Hinduism. We appreciate if you send News, information or suggestion.


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