#45: Obstacle ahead

40% of height clearance NOC applications are rejected by the Airports Authority of India

Image edited via ChatGPT

The Government of India plans to build airports in 29 cities over the next two decades. These projects promise more than terminals and runways; they create hubs that can attract businesses and generate jobs. However, offices, hotels, and homes around these hubs require a No Objection Certificate from the Airports Authority of India (AAI) prior to construction.

Every proposed building must be evaluated for its proximity to airports and its planned height to determine whether an NOC is required from AAI. In effect, AAI’s approval is required in a 5,78,002 square kilometre area covering 18% of India’s landmass¹. AAI’s NOC is among a minimum of 19 pre-construction documents required to construct a building. This one NOC is responsible for inordinate delays, regulatory confusion, and increased costs.

This article shows what India’s airport regulations mean for construction around airports. In the article, we summarise airport regulations that impact building construction, examine AAI's administrative data on NOC approvals, scrutinise AAI’s Permissible Top Elevation of buildings across cities, and describe one alternative approval regime. Through this assessment, we identify opportunities for reform that balance safety concerns with India's urgent need for urban development around its growing airport infrastructure.

The AAI NOC

Two criteria determine whether a building needs an NOC from AAI: where a building is located in relation to an airport, and how tall the building will be. These are outlined in the Ministry of Civil Aviation (Height Restrictions for Safeguarding of Aircraft Operations) Rules, 2015 (G.S.R. 751(E), dated 30 September 2015).

All structures within a 20 km radius of the aerodrome require an NOC (Rule 5). In addition, building heights are controlled based on their distance from the airport (Schedule II). Under the rules, there is a no-construction zone extending up to 500 m around the runway strip. Beyond this, there is an 'inner horizontal surface' extending up to 4 km from the aerodrome, where no building can be taller than 45 m. Further out, the regulations mark an ‘outer horizontal surface’ where permissible height increases by 1 m for every 20 m of distance from the aerodrome, with an upper limit of 300 m up to a 15 km radius. Finally, there is a peripheral zone between 15 - 20 km, where buildings are asked to obtain an NOC but are not subjected to a height cap.

Until 2015, NOCs could only be obtained from AAI. In 2015, the AAI introduced Colour-Coded Zoning Maps (CCZMs) to delegate some of the responsibility of granting approvals to local authorities. In each coloured zone, buildings with height below the prescribed threshold can be approved by local authorities directly (Rule 7(2)).

In sum, there is a height cap based on how far a building is from an airport, and there is a threshold height beyond which AAI’s no objection is needed.

Figure 1: Process flowchart on who needs an AAI NOC and from whom

To obtain the NOC, the applicant has to submit a certificate of site elevation and site coordinates from licensed surveyors approved by local bodies or empanelled private surveyors, along with photographs of the site and neighbouring areas taken by a surveyor, and the site plotted on Google Earth. The applicant is issued an NOC valid for 8 years if the application is approved.

A tale of delays and rejections

The AAI receives applications through the online NOC Application System and publishes its decisions on the portal. All decisions since January 2016 are publicly available.

We analysed data from the portal for 12 states from 01 January 2016 to 18 November 2024. Between them, these states account for 65% (112/174) of all airports in India. Builders applied for an NOC near 100 of these 112 airports. The table below shows the total number of airports in each state and the subset of airports where builders filed an NOC application.

Number of applications: The AAI decided on 96,342 applications between 2016 and 2024, an average of 10,696 decisions per year. These applications grew at a compound annual growth rate (CAGR) of 7.41%. Maharashtra had the highest number of NOC application decisions, accounting for 41% of all decisions between 2016 and 2024. Within states, half of all applications were concentrated around just one airport. While we don’t know how many applications remain undecided with AAI, these numbers give us an estimation of the size of the red-tape problem.

Figure 2: Number of applications between 2016 and 2024

Time to decision: The AAI mandates a 15-day timeline for processing NOC applications (Airports Authority of India, 2016). AAI took a median of 14 days to process and issue decisions. However, the days to decision for rejection and acceptance were different. AAI took a median of 3 days to reject applications and a median of 25 days to accept applications.

Figure 3: Median days to decision for NOC applications

The AAI meets the 15-day timeline for 53% of applications. The authority meets the deadline 94% of the time when rejecting applications and only 27% of the time when approving applications. 77% of applications are processed within a month, and 97% within three months.

Figure 4: % of applications that exceed the mandated timeline

Approval/Rejection rate: AAI approves only 58% of all processed applications. The approval rate varies across states. While more than 75% of applications in West Bengal are approved, only 30% of applications in Rajasthan are approved. Nine airports in India had a 0% acceptance rate, while two airports had a 100% acceptance rate.

Figure 5: Acceptance and rejection rates for NOC applications

AAI has published a document listing 19 common reasons why NOC applications are rejected. AAI claims that applications are denied due to documentation errors, like incorrect format, mismatch of site coordinates in the application and the site elevation certificate, and incomplete information about the owner.

How tall is too tall?

In 2015, the AAI introduced Colour-Coded Zoning Maps (CCZMs) to specify when builders need to approach the AAI for approval. Thus far, AAI has released CCZMs for 88 airports. For each coloured zone, the map specifies the Permissible Top Elevation (or, height, in loose language) beyond which builders must apply to AAI for an NOC. Here is an example of a colour-coded zoning map.

Figure 6: Colour-coded zoning map of Mumbai, Maharashtra (Click on the map to explore)

We analysed the CCZMs released for 12 cities. For each CCZM, we recorded the Permissible Top Elevation at set distances from the airport, and after accounting for the elevation of the aerodrome and sea level, converted these into building height thresholds. Maps of the nature of CCZMs inevitably have fuzzy edges and rules. We estimated the most prevalent building height threshold in a given zone and tabulated these. This analysis gives us a picture of the de facto AAI approval choke point for different locations in these 12 cities.

There is a fair bit of variation in the building height thresholds across 12 cities as set out in the CCZMs. The thresholds for buildings in different distance-from-airport bands are much lower in metropolitan cities than in tier-2/tier-3 cities. AAI’s risk appetite is far greater in some cities, allowing more local delegation of approvals.

For example, at 4 km from the airport, in Mumbai all buildings above 17.87 m need AAI approval, but in Vijayawada only buildings above 42.14 m need AAI approval. At 7 km from the airport, in Amritsar buildings above 39.2 m need AAI approval, but in Warangal only buildings above 140 m need AAI approval. In the peripheral zone, AAI typically requires approval only for buildings taller than ~100 m. But, in Delhi and Mumbai builders constructing even 2 to 6-storey buildings in these areas may require AAI approval given the overlaps of the zones.

Intuitively, as distance from the airport increases and the commensurate safety risk reduces, one must see a strong and somewhat consistent increase in the building height thresholds. However, AAI only applies this logic in a few cities. In Amritsar, Bhubaneswar, and Chennai, the building height threshold increases by 100% as the distance from the airport increases from 6 to 15 km. Contrastingly, in Ahmedabad, Lucknow, and Vijayawada, this increase is barely 35%. At 9 km from the airport, thresholds are as low as 19.6 m in Jaipur and as high as 58 m in Ahmedabad. In Bhubaneswar, up to 9 km from the airport, and in Jaipur, up to 15 km from the airport, the building height threshold is low and unchanging. But as soon as we cross these distances, the threshold increases by 600%.

Similarly, one would expect that in the most populated cities with airports close to the city centre the thresholds might be similar. However, even among metropolitan cities, the threshold varies significantly. The threshold starts at 7.77 m in Delhi, 17.87 m in Mumbai, and 29.5 m in Chennai.

CCZMs were introduced to delegate more approval authority to local bodies. However, the cities that need the most relief are the cities where AAI has done the least amount of delegation. AAI’s conservative thresholds in metropolitan cities focus on the size of risk given the population densities in these areas, but miss the point that local bodies in these cities have the highest state capacity for technical regulation.

An example of how to do regulation differently

In India, most builders in a city have to wait for approval from a Union-level authority before any construction. This structure of approval leads to delays and increases in the cost of construction. For example, the Practising Engineers, Architects and Town Planners Association report that over 250 high-rise projects in Mumbai have stalled due to months-long delays in AAI approval.

In contrast, the USA offers a more flexible regulatory approach. The Federal Aviation Administration (FAA) follows a two-tier system. First, buildings above a certain height threshold need to notify the FAA without requiring further investigation (14 CFR 77.5). Second, at higher thresholds, the FAA conducts studies to assess whether a building poses a "hazard to air navigation" (14 CFR 77.31). These studies result in one of three determinations: no hazard, no hazard with conditions, and hazard.

The FAA's determination is an important factor, but it is not dispositive. The FAA cannot ‘approve’ or ‘deny’ construction; they only release the findings of the study, which do not have any enforceable legal effect (Transportation Research Board & National Academies of Sciences, Engineering, and Medicine, 2012). As stated under Aircraft Owners and Pilots Association v. Federal Aviation Administration:

“The FAA is not empowered to prohibit or limit proposed construction it deems dangerous to air navigation. Nevertheless, the ruling has substantial practical impact. ...The ruling may also affect the ability of a sponsor proposing construction to acquire insurance or to secure financing. Primarily, however, the determination promotes air safety through "moral suasion" by encouraging the voluntary cooperation of sponsors of potentially hazardous structures.”

The threshold at which the FAA has to conduct a safety study is much higher than the threshold at which AAI requires approval. Thus, in the USA, the Federal Aviation Administration (FAA) allows taller buildings closer to the airport with less red tape. As the table below shows, most builders in New York can begin construction after notifying the authorities, instead of waiting for approval.

The advisory nature of the FAA's role allows for local discretion in development approvals. Local authorities can decide if the building ought to be constructed based on considerations of aviation safety, economic development, housing needs, and urban planning objectives.

Balancing safety with growth

Literature and popular discussion highlight the tension between air safety and economic growth in urban centres. Nakajima & Takano (2023) show that height restrictions around airports reduce land value, particularly in city centres. They take the example of Fukuoka’s airport, 4 km from the central business district. In the inner horizontal zone where the height is capped at 45 m, the land value reduced as the distance from the airport increased. Beyond the 4 km, the land value increased as the permissible height and the distance from the airport increased. Similarly, Lee & Kim (2018) show that height limits around the air force base in Sujeong-gu, South Korea, reduced the value of apartment buildings. The property values around the air force base rose sharply when the height limits were relaxed.

India’s airport proximity and height standards are informed by the International Civil Aviation Organisation (ICAO) recommendations. However, some countries have adopted standards and processes that are far more liberal without compromising on safety (Silva & Barros, 2016; Spring & McNerney, 1996). Even ICAO recognises the need to “create a better economic balance between ground space and airspace” (Obstacle Limitation Surfaces Task Force, 2016). Countries like Bangladesh have highlighted the impact of airport regulations on developing high-rise commercial buildings in an international forum (Director General of Civil Aviation, Bangladesh, 2023). These cases underscore the importance of resolving airport proximity height regulations that impact economic growth.

Indian authorities have deregulated some controls around airports to respond to increasing demand. In the late 2000s, the AAI increased the maximum permissible height of buildings around airports from 150 to 300 m. In the past, AAI has exercised its discretion to allow buildings taller than the permissible height. Recently, height limits around the under-construction Navi Mumbai Airport were increased from 55 to 150 m, even as the final technical and operational plans are being finalised.

In addition, our analysis points to the following reforms: First, AAI can increase the Permissible Top Elevation for different zones, particularly in large economic centres. Second, AAI can rethink the restrictions in the peripheral zone (15 to 20 km away from the airport) as they are likely to pose the lowest risk to human safety. Third, AAI can advise states to implement a notice-based regime for buildings below the Permissible Top Elevation, as AAI has declared them low-risk from an aviation obstacle hazard point of view.

Conclusion

The AAI's NOC process affects construction across 18% of India's landmass. Analysis of administrative data from 2016 to 2024 reveals that applications have increased at 7.41% annually, reflecting the rising demand for floor space in India. Despite innovations like colour-coded zoning maps, construction projects across India, including infrastructure projects, face delays and uncertainty. Besides processing delays, AAI’s risk-averse approach introduces unpredictable risks for developers like in the case of Armaan Real Estate Private Limited vs Union Of India(Armaan Real Estate Private Limited vs Union Of India, 2022).

This analysis does not unpack the role of local authorities in simplifying building permissions. Our cursory study shows several opportunities for states to reform aviation obstacle hazard assessment. Even with the introduction of CCZMs and declaration of Permissible Top Elevation, some states still demand the same compliance as AAI, including in the case of buildings eligible for self-certification. This issue needs to be examined carefully.

Airport regulations shape Indian skylines and may limit vertical growth in dense urban centres where land commands premium prices. As the number of airports in India grows, AAIs height restrictions will increasingly shape our cities. Addressing some regulatory challenges can help India balance aviation safety and growth.

References

Aircraft Owners and Pilots Association v. Federal Aviation Administration, No. 195 U.S.App.D.C. 151,600 F.2d 965 (U.S. Court of Appeals — District of Columbia Circuit 5 June 1979). https://case-law.vlex.com/vid/aircraft-owners-and-pilots-892628525

Airports Authority of India. (2015). Guidelines for the applicants. https://nocas2.aai.aero/nocas/AAI_Links/Guidelines_Applicant1.pdf

Airports Authority of India. (2016). Air Traffic Management Circular No 9 of 2016 (No. ED/ATM/2016/311609/ATMC/NOC). https://stagenocas2.aai.aero/nocas/AppealProceeding/Archive/ATMCNo.9of2016.pdf

Airports Authority of India. (2021). List of AAI empanelled Survey firms (No. GIS Circular 03/2021). Government of India. https://nocas2.aai.aero/nocas/AAI_Links/LIST_OF_AAI_SURVEY_FIRMS.pdf

Airports Authority of India. (2022). Common reasons for rejection. https://nocas2.aai.aero/nocas/AAI_Links/Common_grounds_for_rejection_of_Application_at_Verification_stage.pdf

Airports Authority of India. (2025). No Objection Certificate Application System (NOCAS). https://nocas2.aai.aero/nocas/

Armaan Real Estate Private Limited vs Union Of India, No. Writ Petition (L) No.1752 Of 2022 (High Court of Bombay 27 January 2022). https://indiankanoon.org/doc/54879760/

Civil Aviation Authority. (2020). Safeguarding of Aerodromes (No. CAP 738). Government of the United Kingdom. https://www.caa.co.uk/publication/download/12346

Construction World. (2022a, January 24). Redevelopment near Juhu airport stuck due to height restrictions. https://www.constructionworld.in/transport-infrastructure/aviation-and-airport-infra/-redevelopment-near-juhu-airport-stuck-due-to-height-restrictions/32164

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Director General of Civil Aviation, Bangladesh. (2023, October 19). Obstacle Limitation Surfaces of an Aerodrome Versus Economic Growth in Urban Areas. 58th Conference Of Directors General of Civil Aviation Asia and Pacific Regions, Bangladesh. https://www.icao.int/APAC/Meetings/2023%20DGCA%2058/58-DP-04-03_BGD_231004_OBSTACLE%20LIMITATION%20SURFACES%20OF%20AN%20AERODRO.pdf

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Lee, H., & Kim, Y. (2018). The Effects of Air Force Regulation on the Housing Market Price: The Case of Apartments in the City of Seongnam. Journal of the Association of Korean Geographers, 7(1), 97–113.https://journal.kci.go.kr/JAKG/archive/articleView?artiId=ART002338531

Moneycontrol. (2022, July 30). Boost for real estate: AAI allows Navi Mumbai buildings to climb 48 floors. https://www.moneycontrol.com/news/business/real-estate/boost-for-real-estate-aai-allows-navi-mumbai-buildings-to-climb-48-floors-8922291.html

Nakajima, K., & Takano, K. (2023). Estimating the effect of land use regulation on land price: At the kink point of building height limits in Fukuoka. Regional Science and Urban Economics, 103, 103955. https://doi.org/10.1016/j.regsciurbeco.2023.103955

Obstacle Limitation Surfaces Task Force. (2016). Aerodrome Obstacle Surfaces – The new concept. International Civil Aviation Organization. https://www.icao.int/SAM/Documents/2016-SUPLIM/RPEAGA7_NI_04_Ap%C3%A9ndice%20B_Obstacle%20Surfaces-%20the%20Concept-%20draft-%20OLSTF-5%20Final%20with%20comments.pdf

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The Hindu. (2022, May 17). Mysuru-Chamarajanagar track electrification hits hurdle of NOC from AAI. The Hindu. https://www.thehindu.com/news/national/karnataka/mysuru-chamarajanagar-track-electrification-hits-hurdle-of-noc-from-aai/article65422758.ece

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1. India has 44 Instrument Flight Rules (IFR) airports without Colour Coded Zoning Maps (CCZM), 88 IFR airports with CCZM, and 27 Visual Flight Rules (VFR) airports. AAI can limit building heights within a 56-kilometre radius of IFR airports without CCZM and a 20-kilometre radius around IFR and VFR airports. This covers a total area of 5,78,002 square kilometres.

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Bhuvana Anand, Sargun Kaur, and Arjun Krishnan are researchers at Prosperiti.