India, Feb. 27 -- The fate of Mumbai Metro 7A or the Gundavali-Chhatrapati Shivaji Maharaj International Airport line is hanging in the air. During the construction of the line, the Mumbai Metropolitan Region Development Authority (MMRDA) discovered that the Airport Authority of India's (AAI) permission on the air funnel zone had been breached by a general consultant, and a revised nod has now been sought.

An air funnel zone is a flight path, similar to road lanes, in which an aircraft is supposed to be airborne. A funnel zone is defined for safety, hence any impediments to it can potentially endanger aviation safety.

The 3.42-km Metro 7A corridor, partially elevated and partially underground, is being constructed by J Kumar Infraprojec...