Thank you for that hint, I now found some discussions and articles mentioning that proposal and why it wasn't taken up:
In particular
quotes an Indian Vice Admiral: "In light conditions, the endurance of the aircraft goes down from five to just one hour. And for an early warning aircraft to have the capability of staying for only one hour makes no sense. We have decided not to consider the Hawkeye. There are other reasons for not taking up the Hawkeye offer. In a full take-off, a single engine failure could be disastrous"