Definition
A surface-based weather phenomenon in which sand is lifted by the wind to a height of six feet or more above the ground, reducing horizontal visibility to less than seven statute miles. Reported in aviation weather observations using the contraction BLSA.
Plain English
Wind picking up sand from the ground and carrying it high enough and thick enough to make it hard to see across the airfield.
Context Anchor
Seen in aviation weather reports and in operations near dry, sandy areas, especially during taxi, takeoff, landing, or low-level flight.
Why Pilots Care
It cuts visibility during takeoff, landing, and low-level flight while also risking engine damage from ingested particles.
Grounding Statement
Picture a strong wind lifting a tan cloud of sand across the runway, not just a few grains sliding along the ground.
Intuition Check
Blowing sand does not just mean sand is moving on the surface. In aviation weather use, it means wind has lifted sand into the air high enough to reduce what you can see.
Example Sentence 1
The METAR reported blowing sand with visibility down to three miles, so the pilot delayed departure until conditions improved.
Example Sentence 2
The pilot delayed departure after the briefing warned of blowing sand near the destination airport.