I am traveling from India to Ecuador via London Heathrow on November 28. I will be at LHR on 28th at 6:20 am and departing at 10:25 am. I'm an Indian national and go to Ecuador on arrival visa and my second layover in Miami USA there is only 1 hour and 55 minute stay. Do I need a transit visa to stay airside?
There are no transit corridors at US airports (i.e. you cannot stay airside), meaning you'll need a transit visa for the US (type C1).
As for the UK, as stated on the GOV.UK website, because you hold valid a US visa, you do not need a visa for transiting the UK.
So you need one visa only: a C1 visa for the US