Investigation Summary
The aircraft arrived at LaGuardia from Jacksonville already behind schedule due to poor weather and the removal of baggage for a passenger who elected not to board. During its time at the gate, it was deiced with Type I fluid, but a mechanical failure of a deicing truck blocked the aircraft for 20 minutes, prompting the captain to request a second deicing. After the second treatment, the aircraft began a long taxi to Runway 13. During this period, the crew discussed the possibility of ice accumulation, but the first officer's visual checks from the cockpit were hampered by the closed sliding window and the limited effectiveness of the wing ice light. The NTSB later determined that the crew should have entered the cabin to get a better view of the wings or performed a tactile inspection. Furthermore, the investigation revealed that the captain initiated rotation at 119 knots, which was 5 knots below the proper rotation speed of 124 knots for the conditions, further reducing the margin of safety on the contaminated wings.
Final Conclusions
The National Transportation Safety Board (NTSB) determined that the probable cause of the accident was the failure of the flight crew and the airline to ensure that the aircraft's wings were free of ice contamination before takeoff. Contributing factors included the lack of industry-wide standards for deicing fluid holdover times and the inadequate procedures for flight crews to inspect wing surfaces from the cockpit in low-visibility conditions. The investigation also highlighted the aerodynamic sensitivity of the Fokker F28's hard-wing design to even minute amounts of surface roughness.
Photographic Evidence (1)
Video Analysis
Icing On Air Ontario Flight 1363 & USAir Flight 405 Results In ... — A detailed look at how wing icing and inadequate deicing procedures led to the crashes of Air Ontario 1363 and USAir 405.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Systems & Failure Modes
Type I Deicing Fluid
A heated mixture of water and glycol used to remove existing ice; it provides very limited protection against further accumulation compared to Type II or IV fluids.
Wing Ice Light
A light mounted on the fuselage designed to illuminate the wing leading edge to help the crew detect ice during night operations.
Fokker F28 Wing Design
A 'hard wing' design without leading-edge slats, making it highly sensitive to aerodynamic disruptions caused by small amounts of ice.
Interesting Facts
- 01The aircraft was deiced twice with Type I fluid, which has a very short holdover time in active precipitation.
- 02The captain used an empty coffee cup on the flap handle as a reminder to set the flaps before takeoff.
- 03The first officer checked the wings for ice at least three times during the taxi, but did not see the clear ice buildup.
- 04The NTSB found that the captain rotated the aircraft 5 knots earlier than the recommended speed of 124 knots.
Safety Actions & Advisories
Holdover Timetables
The FAA developed and implemented standardized holdover time (HOT) guidelines to help pilots determine how long deicing fluids remain effective.
Tactile Inspection Requirements
Procedures were updated to require physical 'hands-on' checks of wing surfaces for certain aircraft types when icing conditions are present.