Abstract: A method of controlling an optical fiber splicing machine utilizes a power control mode to control the amount of power delivered to fuse the fibers. In the power control mode, the attenuation is measured while the fusing process is occurring. The power control mode shuts down the splicer when the measured insertion loss is less than or equal to the target insertion loss value plus a margin value. The margin value accounts for the transient attenuation difference value indicative of the changing attenuation as the splice cools. If the desired attenuation is not achieved, an energy control mode is utilized which controls the amount of energy delivered to fuse the fibers. After delivering this energy, the method measures the attenuation. If not within desired values, the energy mode is repeated. At each iteration the splicing control function utilized by the energy control mode may be reprogrammed. With these techniques, optical fibers may be spliced having a controlled attenuation to within +/−0.