Airports are capable of staying open on runways when there is snow, but when a small layer of contamination is placed on the lifting surfaces of an aircraft, it can lead to closure of the safety margin within seconds.
The Bombardier Challenger twin-engine business jet bound to depart Bangor International Airport in Maine was overturned and burned after takeoff clearance during a period of winter weather, which led to a federal investigation into the plane, crew behavior and the conditions in which it was operating. It was an aircraft of Bombardier Challenger 650, a member of an older series called Challenger 600 and Federal Aviation Administration and National Transportation Safety Board investigators were appointed to the case.
The initial accounts on the number of occupants were all over, as it was a common point at the early stages of a major accident, and the information had to be disseminated among the population. The officials on the ground at the airport later indicated that the flight manifest indicated six people on board and no one was taken to a hospital and that the first federal messages mentioned eight. One of the reasons is the uncertainty that encourages engineering-based readers to wait until the NTSB has provided its systematic reconstruction, relying on recorded communications, performance data, examination of the wreckage, and operational records and then starts to reduce itself to causal chains.
What is already evident in the publicly available operationally available information is that the flight was being flown in the traditional classic “cold-soak” and contamination-prone conditions: below freezing temperatures, falling snow, and a low ground turn. Incident notes by users linked to surveillance and transponder tracks reveal that the plane had come into Houston earlier in the evening and then asked to have Type 1 and Type 4 de-ice and anti-ice fluid applied before getting in line to take off. Type I fluid is used mainly to de-ice, meaning to remove any contamination that already exists whereas Type IV is used to anti-ice and provide holdover. Practically, the level of protection is determined by precipitation rate, temperature, fluid mixture, and time of application to take off as well as any further exposure during taxi and queueing.
Aviation safety experts have made numerous calls to point out that even a small quantity of snow or ice has the capability of disturbing airflow to the extent of affecting the quality of lift and raising the stall speed at the very time an aircraft is in committed flight. The Challenger 600 series specifically has been linked to previous icing-related issues during takeoff and an aviation safety consultant interviewed in “press reports said the type had a history of icing during takeoff.” That history does not predetermine what causes any particular accident, but it does influence the checklist culture of “clean wing” checking and the conservatism which is demanded when visibility, precipitation and surface temperatures narrow the envelope.
Immediate severity of the event was spread through audio excerpts of air traffic control communications that included the following line: Aircraft upside down. We have an upside down passenger plane. These types of recordings, including the video of the airport surveillance and any other onboard data sources, generally will assist investigators to match the acceleration, directional control, rotation, and any other unusual indicators reported by the controllers onboard or the crews nearby.
Another context of operation is the geography of Bangor. The airport is located on a common transatlantic routing path and business jets stopping to fuel are often prompted to choose it prior to flying abroad. The involved flight was on record in incident details as flying towards the Vatry/Chalons-en-Champagne International Airport in France, a mission profile which can heighten schedule pressure and expose the flight to the rapid turnaround in the unfavorable weather.
The NTSB investigative handbook is also systematic: pilot qualification and recent activity, aircraft maintenance condition, weather and lighting, de-icing history, and performance calculations are not evaluated separately, but in conjunction. The preliminary report is usually published in 30 days whereas the final report may take 12 to 24 months, as it has to take time to test the hypotheses with the physical evidence and tested data.
To engineers and operators, the timeless lesson of the accident is not the visual drama of the fire but the fact that operations in the winter are determined by minute, accumulating factors-fluid choice, holdover tolerance, tactile checks, taxi time, and disciplined go/no-go-decisions, all of which are banal until the time it is not.
