Sanjay Gandhi, the 33-year-old heir-apparent to India's Nehru-Gandhi political dynasty, died today when a small plane in which he was flying crashed shortly after takeoff.

Gandhi, chief political adviser and close confidant to his mother, Prime Minister Indira Gandhi, had just fashioned his most spectacular political success by guiding the ruling Congress-I (for Indira) Party to victory in eight of nine state elections.

It was mainly his young supporters who carried the party to victory, taking over for many of the long-time Congress Party workers dating back to his grandfather, India's first prime minister, Jawaharial Nehru.

As a result of his party's stunning victory, Sanjay Gandhi was being pushed as the eventual successor to his 63-year-old mother as the next prime minister of India.

As Nehru had groomer her, so Indira Gandhi gave her son a high party post, as one of four general secretaries. Previously, he had held no official party position and won his first elected office in January as a member of India's parliament.

The prime minister was reported to be among the first to arrive at the crash scene, located very close to her official residence, in the heart of New Delhi.

According to United News of India, she raced there in the ambulance that took him to a nearby hospital, where doctors said he could not be revived.

According to early reports, he was flying with a companion who was the chief instructor of the Delhi Flying Club when his light plane crashed into a row of apartments for low-level government clerks.

The instructor died in the crash, but there were no reports of fatalities among the apartment dwellers.

Eyewitnesses told United News of India that the plane's engine stopped suddenly while it was not too high off the ground. They said the plane spun and then plunged to the earth.

The crash site was just behind the sprawling English-style bungalow that Indira Gandhi had used as her residence and political headquarters during the 33-months that she was out of power.

After her overwhelming reelection victory in January, she moved into the official prime minister's residence and Sanjay took over the house at 12 Willingdon Crescent as his political headquarters while he lived with his mother. Every afternoon he would greet political supporters and petitioners for favors in the front yard of the house.

Sanjay and his mother were closely linked by their love of politics. She refused during her time out of office to distance herself from him even though he was blamed for her March 1977 defeat because of excesses in slum clearance and family planning programs.

As other supporters melted away, Sanjay continually advised his mother to remain active politically. This work paid off in the January election.

Sanjay Gandhi was keen on flying and gliding and used to pilot his own plane every morning before beginning the day's work. He started flying in 1976 and held both a commercial pilot's license and an instructor's rating.