Installing:
replace androm.dff and .txd in your gta3.img with the ones provided in the file and place the .cs inside your CLEO directory

Press the Equal button while in a plane to request a tanker. The tanker will travel faster when in a Hydra or a Shamal and will be slower for other planes.

Alternatively you can refuel at the airports marked on the radar by default Fuel System implemented
Fuel Gauge added on the HUD while in planes and helicopters
Fuel Gauge illuminates at nighttime
Refueling at airports now possible
Tanker aircraft arrives faster and will allow refueling
When planes run out of fuel they will drop to the ground
When helicopters run out of fuel they will gradually fall to the ground