When an airport is built within a city, safety normsensure the buildings that fall under the shadow of aircraft remain stunted forever. Which is why the fate of about 3.6 lakh residents who live in the 6,000-odd buildings in Vile Parle, Santacruz, Kurla and Ghatkopar that fall under the aircraft approach paths is different from those who reside elsewhere in the city. Due to height restrictions, no builder will take up their buildings for reconstruction. If left to their own fate, a decade from now, some of these dilapidated buildings would begin to collapse.

Airports Authority of India's (AAI) flight safety norms dictate no building that stands under the funnel zone — the imaginary conical path that extends outwards and upwards from the two ends of a runway — should grow tall enough to come close to the flight paths. Which is why none of these "airport-affected buildings," as they can be called, is being taken up by builders for redevelopment.

The reason is, these are buildings that fall under what's called the airport funnel zone: an imaginary, conical tunnel that extends outwards and upwards from the shorter two ends of the rectangle-shaped runway. Like a hollow ice-cream cone with some portion near its pointed tip cut off. Each runway end has such a funnel, which is an obstacle-free path for aircraft to descend onto or climb from the runway. Since Mumbai airport has two runways, it has four runway ends and so four funnels. Those that stand closest to the runway end are ground-plus-one-storey structures, and those at the farther end, which is up to 4km into the funnel, are allowed to grow up to five storeys.

Airports Authority of India's (AAI) flight safety norms dictate no building or structure that stands under the funnel zone should grow tall enough to cut into these flight paths or even come closer to them.