A $21 million plan for Colorado to buy an aerial firefighting fleet designed to spot and attack wildfires faster has won initial approval in the Senate. The bill is a response to historic back-to-back wildfire seasons. The measure calls for the state to buy two spotter planes to detect fires within an hour after the first sighting of smoke. It would also contract four helicopters and four single-engine tankers to begin fire suppression within an hour of a request from fire chiefs. Senators gave the measure unanimous preliminary approval. One more formal vote is required before the measure goes to the House. Colorado’s budget for next year already accounts for the aerial firefighting fleet.