RAF Santacruz was constructed in the 1930s.
It was a bigger airfield than nearby Juhu Aerodrome and was home to several RAF squadrons during World War II from 1942 to 1947.
The Airport covered an area of about 1,500 acres (610 ha) and initially had three runways.
The apron existed on the south side of runway 09/27, and the area, referred to today as the "Old Airport", houses, among others, maintenance hangars of Air India, Air Works India, Indamer Aviation Pvt Ltd. and MIAL's General Aviation Terminal.

By 1946, when the RAF began the process of handing over the airfield to the Director General of Civil Aviation for Civil operations, two old abandoned hangars of the Royal Air Force had been converted into a terminal for passenger traffic.
One hangar was used as a domestic terminal and the other for international traffic.
It had counters for customs and immigration checks on either side and a lounge in the center.
Air India handled its passengers in its own terminal adjoining the two hangars.
In its first year, it handled six civilian services a day.

Traffic at the airport increased after Karachi was partitioned to Pakistan and as many as 40 daily domestic and foreign services operated by 1949, prompting the Indian Government to develop the airport, equipping the airport with a night landing system comprising a Radio range and a modernised flare path lighting system Construction of a new passenger terminal and apron began in 1950 and was commissioned in 1958.
Named after the neighbourhood in which it stood and initially under the aegis of the Public Works Department, the new airport was subsequently run by the Ministry of Civil Aviation.

With the dawning of the Jumbo Jet era in the 1970s, Santacruz, despite several extensions, began suffering from insufficient operational capacity.

The Santacruz terminal was designed to accommodate 600 passengers at any given time, but by the late 1970s, it was handling 1,200.
In 1979–80, 5 million domestic and international passengers flew into and out of Santa Cruz compared with 3 million at Delhi's Palam Airport.
The airlines were constantly expanding their services but there was no corresponding increase in space at the terminal, making it the most congested airport in the country.
In one of its issues, Time magazine, referring to the chaos, called the terminal building a 'black hole'.

A major fire gutted the International section of the terminal building on 21 September 1979, killing three passengers and shutting down the airport.
A temporary departure extension or "Gulf Terminal" was made functional in October that year until the terminal was repaired.

The Tata committee, set up in 1967 to examine the issues concerning the airport, had recommended the construction of a new international terminal to meet the requirements of traffic in the seventies.
The Santa Cruz terminal was to be used for domestic traffic alone.
The International Airport Authority of India (IAAI), which was set up in 1972, started planning the construction of a new terminal building for handling international passenger traffic, to be completed by 1981.
Accordingly, construction of the new International terminal at Sahar to the north-east of Santacruz in Andheri was taken up at an estimated cost of ₹ 110 million.

Construction of the new international terminal at Sahar began in November 1977, and the first phase took three years to build.
Sahar Terminal 2A, the first phase of the three-part terminal, was opened on 5 December 1980.

AAI had been considering the modernisation of Mumbai airport in 1996 although the AAI board approved a modernisation proposal only in 2003.
By then, Mumbai and Delhi airports were handling 38% of the country's aircraft movement and generating one-third of all revenues earned by AAI.
At that time, the Mumbai airport handled 13.3 million passengers, 60% of which were domestic travellers.
The airport faced severe congestion for both aircraft and passengers as it was handling twice as many aircraft movements per day than it was originally designed for.
The bidding process for its modernisation
RAF Santacruz was constructed in the 1930s. It was a bigger airfield than nearby Juhu Aerodrome and was home to several RAF squadrons during World War II from 1942 to 1947. The Airport covered an area of about 1,500 acres (610 ha) and initially had three runways. The apron existed on the south side of runway 09/27, and the area, referred to today as the "Old Airport", houses, among others, maintenance hangars of Air India, Air Works India, Indamer Aviation Pvt Ltd. and MIAL's General Aviation Terminal.
By 1946, when the RAF began the process of handing over the airfield to the Director General of Civil Aviation for Civil operations, two old abandoned hangars of the Royal Air Force had been converted into a terminal for passenger traffic. One hangar was used as a domestic terminal and the other for international traffic. It had counters for customs and immigration checks on either side and a lounge in the center. Air India handled its passengers in its own terminal adjoining the two hangars. In its first year, it handled six civilian services a day.
Traffic at the airport increased after Karachi was partitioned to Pakistan and as many as 40 daily domestic and foreign services operated by 1949, prompting the Indian Government to develop the airport, equipping the airport with a night landing system comprising a Radio range and a modernised flare path lighting system Construction of a new passenger terminal and apron began in 1950 and was commissioned in 1958. Named after the neighbourhood in which it stood and initially under the aegis of the Public Works Department, the new airport was subsequently run by the Ministry of Civil Aviation.
With the dawning of the Jumbo Jet era in the 1970s, Santacruz, despite several extensions, began suffering from insufficient operational capacity.
The Santacruz terminal was designed to accommodate 600 passengers at any given time, but by the late 1970s, it was handling 1,200. In 1979–80, 5 million domestic and international passengers flew into and out of Santa Cruz compared with 3 million at Delhi's Palam Airport. The airlines were constantly expanding their services but there was no corresponding increase in space at the terminal, making it the most congested airport in the country. In one of its issues, Time magazine, referring to the chaos, called the terminal building a 'black hole'.
A major fire gutted the International section of the terminal building on 21 September 1979, killing three passengers and shutting down the airport. A temporary departure extension or "Gulf Terminal" was made functional in October that year until the terminal was repaired.
The Tata committee, set up in 1967 to examine the issues concerning the airport, had recommended the construction of a new international terminal to meet the requirements of traffic in the seventies. The Santa Cruz terminal was to be used for domestic traffic alone. The International Airport Authority of India (IAAI), which was set up in 1972, started planning the construction of a new terminal building for handling international passenger traffic, to be completed by 1981. Accordingly, construction of the new International terminal at Sahar to the north-east of Santacruz in Andheri was taken up at an estimated cost of ₹ 110 million.
Construction of the new international terminal at Sahar began in November 1977, and the first phase took three years to build. Sahar Terminal 2A, the first phase of the three-part terminal, was opened on 5 December 1980.
AAI had been considering the modernisation of Mumbai airport in 1996 although the AAI board approved a modernisation proposal only in 2003. By then, Mumbai and Delhi airports were handling 38% of the country's aircraft movement and generating one-third of all revenues earned by AAI. At that time, the Mumbai airport handled 13.3 million passengers, 60% of which were domestic travellers. The airport faced severe congestion for both aircraft and passengers as it was handling twice as many aircraft movements per day than it was originally designed for. The bidding process for its modernisation 
Chhatrapati Shivaji Maharaj International Airport