Related Clues:

• Knitted sweater problem
• Attention-getter in the control tower
• Tiny bump on a graph
• Obstruction
• Planner's problem
• Seize
• Stocking problem
• Stumbling block
• Get hold of
• Air traffic controller's concern
• Hose problem
• Hiccup
• Bottleneck
• Radar notation
• Spot on the radar