Definition
A NOTAM contraction reporting that a runway surface is covered with dry, unconsolidated snow that has not been compacted, packed, or bonded to the surface. The snow is loose enough to be displaced by wind, propeller wash, jet blast, or tire action.
Plain English
A short code used in airport notices to tell pilots that a runway has loose, powdery snow on it — the kind that blows around and gets kicked up by aircraft rather than sticking to the surface.
Context Anchor
Seen in NOTAMs and airport condition information during winter operations.
Why Pilots Care
Loose snow reduces traction and can cause poor braking and directional control issues during takeoff and landing.
Intuition Check
Do not read LSR as meaning snow is currently falling. In this context, it means loose snow is on the runway surface.
Example Sentence 1
The NOTAM included LSR, so the pilot recalculated takeoff distance to account for the added drag from the snow.
Example Sentence 2
With LSR conditions present, braking action was reported as fair and the crew added extra landing distance.