The Great Airport Mystery by Franklin W. Dixon Page A

aloft. The loud clapping of the whirling rotor blades, mixed with the noise of the engine’s muffler, bothered them for a few minutes. But gradually, as the craft gained height, turned and headed northwest, they ceased to think about it. The brothers settled back to enjoy the unobstructed view offered by the transparent canopy, and to watch the pilot.
    â€œI’d like to learn to fly one of these,” Joe commented.
    The flight took a bit longer than their previous trip to the area by airplane. As they flew into the sector they wanted to investigate, Frank scanned the ground below. He spotted the pasture in the aerial photograph and pointed it out to Mack. The pilot bent the helicopter into a series of turns around the field.
    As he leveled the craft out on an easterly heading, Joe glanced to his right. Suddenly the boy detective sat rigid in his seat and stared from the window with an expression of disbelief.
    â€œLook!” he shouted frantically.
    The pilot spun the helicopter around to face in the direction Joe was pointing. Moving toward them was a black, funnel-shaped column of air, stemming from the base of an intensely dark cloud.
    â€œIt looks like a tornado!” Frank yelled.
    â€œIt is!” Mack exclaimed. “They generally move in a northeasterly direction, about thirty to forty miles an hour. We might be able to outrun it.”
    He whirled the craft around, but was greatly alarmed to find that their route of escape was blocked by the surrounding hills. The dark cloud base moving swiftly overhead cut off the possibil ity of climbing out over the top of the higher terrain.

    â€œThe tornado’s getting closer!” Joe shouted
    â€œWhat’ll we do? That tornado is getting closer!” Joe shouted.
    â€œWe’ll have to head for the ground!” the pilot replied grimly.
    As the menacing funnel approached, the surrounding air became turbulent. Mack struggled with the controls as the craft was thrown about viciously. Frank and Joe braced themselves as best they could, while the pilot tried to establish a controlled descent.
    Suddenly Frank and Joe looked out to see a strange phenomenon. The funnel-shaped column seemed to divide in half, as if sliced by an invisible knife. The upper half veered off in a northeasterly direction, while the lower half maintained its original path, passing close to the bobbing helicopter.
    â€œI’m losing control!” Mack shouted. “Hang on! We must be close to the ground!”
    The violent jolt of landing almost knocked the helicopter’s occupants unconscious. They sat dazed for several minutes before regaining their senses.
    Then, gradually, the three became aware of a complete calm. The tornado and dark cloud had disappeared, and not even a breeze was stirring. The sky showed signs of clearing.
    â€œWow!” said Joe. “I hope that never happens to me again!”
    â€œWe’re lucky to have got out of this in one piece,” Mack said grimly
    He got out of the helicopter, followed by the Hardys, and began to examine the craft for damage. The boys, glancing around, realized that they had landed on a corner of the pasture.
    â€œHow’s the copter?” Frank asked.
    â€œThe landing gear is sprung, and there’s some structural damage here and there,” Mack observed. “It doesn’t appear to be serious, but I’d better give the craft a thorough inspection before we attempt to fly it out of here.”
    Frank and Joe decided to investigate the area while the pilot conducted his inspection. They started walking down the pasture toward the high hill situated at the far end.
    â€œHere are those grooves we saw in our photos,” Frank remarked. “They go from one end of the field to the other.”
    He took a tape measure from his pocket and carefully noted the width of the grooves and the distance between them. Pulling out a pencil, he jotted down the figures in his notebook for future