Definition
A NOTAM contraction used to report that a runway surface is covered with snow and ice that has been pressed down into a hard, bonded layer, rather than being loose or slushy. SIR appears in field condition reports and NOTAMs to alert pilots that the runway surface is contaminated and that braking action and directional control will be degraded.
Plain English
A short code on a NOTAM telling you the runway is covered in snow and ice that has been packed down hard, like a skating rink surface. It's a warning that stopping and steering on that runway will be more difficult than on a dry one.
Context Anchor
You may see SIR in airport condition reports, runway condition information, or NOTAM-style notices before a flight into or out of an airport affected by winter weather.
Derivation
SIR is a contraction built from the words Snow, Ice, and Runway. NOTAM contractions are kept short so that runway condition information can be transmitted quickly and consistently in standardized reports.
Why Pilots Care
This information lets pilots judge braking action and decide whether a runway is safe for landing or takeoff.
Grounding Statement
Picture snow and ice pressed flat by traffic into a hard layer on the runway, more like a slick packed surface than loose snow.
Intuition Check
Do not read SIR as just “some snow nearby.” It means packed or compacted snow and ice are on the runway surface itself.
Example Sentence 1
The NOTAM listed the runway condition as SIR, so the captain calculated a longer landing distance and briefed for reduced braking action.
Example Sentence 2
With SIR reported, the crew elected to wait for the runway to be cleared.