"The Sanjay Raj" ended almost before it began today with the death in a plane crash of Sanjay Gandhi, the controversial son of Indian Prime Minister Indira Gandhi and the heir apparent to the political dynasty established by her father.

Gandhi, 33, died this morning when his new American-made light plane crashed while he was practicing aerial acrobatics.

He was considered the second most powerful person in the country, a confidant and chief political adviser to his mother.

Although his official posts were minor -- he was a newly elected member of parliament and one of four general secretaries of the ruling Congress-I (for Indira) Party -- his power was such that he could order Cabinet ministers around and force the transfer of senior civil servants who stood in his way.

He engineered his mother's stunning election victory in January that returned her to power after a humiliating defeat 33 months earlier. That defeat had been partially caused by excesses he committed during her emergency rule. Last month he consolidated the Gandhi comeback by pushing the party to victory in eight of nine state assembly elections.

He picked more than half of the victorious Congress-I candidates for the state assemblies, and one-third of his party's parliamentary members owed allegiance to him.

His death appears likely to complicate government efforts to deal with inflation, armed rebellions in the country's northeastern region, power shortages and stalled economic growth.

Prime Minister Gandhi had ben expected to set to work in earnest on those problems now that she has solidified her power by winning majorities in most state assemblies.

Putting more trust in her son than in anyone else, she reportedly had put him in charge of economic and industrial policy while she concentrated on foreign policy and overall political strategy.

"The impact [of Sanjay Gandhi's death] on Mrs. Gandhi has got to be tremendous, both personally and politically," said a diplomat. "There was an intense personal relationship between the two."

He had advised her against ending the emergency and calling the elections that voted her out of power. He encouraged her to persevere against the Janata government that succeeded her in 1977 and insisted that she could be reelected.

Once he was elected to parliament in December, he became a commanding figure, a junior backbencher courted by the party leaders. He sat among his allies, drawn from the Youth Congress he organized, and became known as "the crown prince."

His supporters changed the face of his mother's Congress-I Party, replacing many of the old-line politicians with fresh faces.

Because of his interest and ability in politics, Sanjay clearly was Prime Minister Gandhi's favorite of her two sons. They spent much of their time together. Sanjay had moved into the prime minister's official residence along with his wife, Maneka, and their three-month-old son, Feroze, named for Sanjay's late father.

Sanjay Gandhi was by far the most controversial figure in India.

To his friends and admirers, such as Indian novelist and newspaper editor Khushant Singh, he had "a warm heart, a puckish sense of humor, fine sense of loyalty towards those who stood by him and, above all else, a demonic zeal to get things done without fuss and fanfare."

Yet, Singh wrote in an appreciation carried in a special edition of the Hindustan Times today, Gandhi continually was "wrongly maligned . . . by wicked politicians and self-styled intellectuals."

Many considered Gandhi ruthless and dishonest, a young man who did not appreciate democratic practices like his grandfather, India's first prime minister, Jawaharal Nehru.

He was blamed for many of the excesses of Indira Gandhi's 21 months of autocratic emergency rule. He embarked on slum clearance projects that left thousands of poor homeless and sponsored family planning programs that included forced sterilizations.

After a coalition led by the Janata Party defeated his mother in March 1977, he led massive demonstrations to try to prevent opponents from bringing criminal cases against them.

At one point his followers stormed a courtroom and destroyed documents being used in a case against him. Two other followers hijacked an airliner to protest the arrest of Indira Gandhi. As a reward for their loyalty, Sanjay Gandhi put them both up as candidates for the state assembly elections in Uttar Pradesh, and they won their seats with surprising ease even though they still face criminal charges for the hijacking.

His major project during his mother's former administration was the Maruti car, designed to be a small inexpensive automobile, which never got off the assembly line. Nevertheless, Sanjay Gandhi and his friends were accused by a Janata-formed inquiry commission of reaping massive profits from the undertaking.

In all, he faced more than a dozen criminal charges and had been convicted on one of them when his mother took office in January. Since then, all the charges have been dropped, and the one conviction was nullified on appeal to the Supreme Court.

Yet even some of his enemies were beginning to admire Sanjay Gandhi's dynamism.

"He gave some sort of political future to the country," said one. "He was more a man of action. He didn't talk very much."

Sanjay Gandhi lay in state today, surrounded by blocks of ice to preserve the body against India's 100-degree heat, as tens of thousands of mourners passed the bier. He will be cremated Tuesday in a ceremony befitting a great national leader at Shanti Vana, the site on the Jamuna River where his grandfather was cremated 16 years ago.

The prime minister, dry-eyed and apparently in perfect control of herself, greeted mourners, many of whom were weeping.

He crashed shortly after 8 a.m. as he was practicing aerial stunts in a special plane that the Delhi Flying Club had just acquired. With him was the club's chief instructor, Capt. Subash Saxena, who also died in the crash.

Moments before the plane crashed, eyewitnesses said, he had rolled a loop over the prime minister's residence.

The plane crashed through trees into a cleared area right behind the sprawling English-style bungalow that Indira Gandhi had lived in when she was out of power. Sanjay Gandhi had taken over the house this winter as a political headquarters and a place to greet followers and petitioners each afternoon. He just missed hitting a block of appartments for low-level government workers.

A qualified commercial pilot with an instructor's rating, Gandhi had first flown the plane -- an American-made Pitts SA2 high-performance aircraft specially designed for stunts -- on Sunday.

A number of air attaches from nearby embassies reported today that they noticed the plane doing low-altitude acrobatics that one called "pretty dangerous stuff" over a developed area. "It could be called irresponsible," said one attache.

No cause has been given for the crash. A special court of inquiry has been appointed to look into it.