Don't mind if I go a bit technical to find out the horizon in BD that Indian drones will observe.
Equation: D = square root of (h^2 + 2*R*h)
Here,
D= Horizon both in India and BD = ?
h = Height of the Drone from the Earth surface = 10,000 -12,000 feet = 3048 - 3657.6 meters
R = Average Radius of the Earth = 6365 kilometer = 6365000 meters
1 meter = 0.001 kilometers
1 feet = 0.3048 meters
So,
D = square root of (h^2 + 2*R*h)
D = square root of (3657.6^2 + 2*6365000*3657.6)
D = square root of (13378037.76 + 46561248000)
D = square root of (46574626037.76)
D = 215811.55 meters
D = 215.81 Kilometer
Now, if the Drone hover just 12,000 feet above the border, then they will observe D * 0.5 = 215.81 * 0.5 = 107.90 Km inside BD territory with zooming facility.