← All explained questions · Supplemental · II — Preflight Procedures
A FROST-COVERED wing exhibits which characteristic?
Choices
Lower stall speed.
Frost INCREASES stall speed.
✓ HIGHER stall speed and reduced lift.correct
Frost raises the stall speed and reduces lift: even very thin frost (smaller than sandpaper) disrupts airflow, increasing stall speed by up to 30% and reducing lift coefficient. Always remove frost before takeoff. Frost-covered wings = higher stall speed + lower lift coefficient. Even sandpaper-thin frost disrupts the boundary layer enough to degrade lift up to 30% and raise stall speed similarly. Many fatal accidents have occurred from pilots taking off with 'just a little frost.' Always physically remove frost before flight; defrost spray may be available, otherwise wait for sun/temperature.
Improved stall recovery.
Frost worsens stall recovery, doesn't improve.
No effect on performance.
Frost has significant negative effect.
Why
Frost raises the stall speed and reduces lift: even very thin frost (smaller than sandpaper) disrupts airflow, increasing stall speed by up to 30% and reducing lift coefficient. Always remove frost before takeoff. Frost-covered wings = higher stall speed + lower lift coefficient. Even sandpaper-thin frost disrupts the boundary layer enough to degrade lift up to 30% and raise stall speed similarly. Many fatal accidents have occurred from pilots taking off with 'just a little frost.' Always physically remove frost before flight; defrost spray may be available, otherwise wait for sun/temperature.
FAA source: FAA-H-8083-25C, PHAK Ch. 5, aerodynamic effects; AC 91-74 if frost/ice contextbrowse the reference library →
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Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question. Reviewed by a panel of three CFIs + AI review.