Emergency Flight Brain Teaser Answer

It will take 3 planes to save the sailor.

This is How

All 3 planes, piloted by Alex, Bob, and Charlie, take off together with full tanks of gas.

After 250 miles, Alex uses 1/2 his fuel to refill both Bob and Charlie and returns to base.

At 500 miles, Bob refills Charlie again, leaving Bob with just enough fuel to return to base.

Charlie continues to the Sailor, drops off the medicine, and immediately starts back with 1/2 tank of gas. At the same time, Alex leaves the base with a full load of fuel to go save Charlie.

At 500 miles, with Charlie running on empty, Alex shares half of his remaining fuel. At the same time, Bob leaves the base with a full tank of gas.

At 250 miles, Bob gives Alex and Charlie each 1/4 of a tank of fuel, leaving all three just enough to return safely to base.