Continental Airlines flight 1404 (Boeing 737-500, registration number N18611) took off left of runway 34R at Denver International Airport (DEN) Colorado ( Crider, 2010) . The flight heading for Houston, George Bush Intercontinental Airport ensued a post crash fire. Out of the 110 passengers on board, 5 sustained major injuries, 40 had minor injuries and the rest were safe including 3, whom were lap held children ( Crider, 2010) . During the time of the accident there was poor visibility caused by meteorological condition, this was accompanied by strong, gusty winds from the West of the runway. According to the National Transport Safety Board the likely cause of the accident was ceasing of the rudder about 4 seconds prior to the occurrence of the strong gusty crosswinds. This was beyond the pilot’s training and experience. Major causes for this accident were: (1) poor dissemination of the weather information by the air traffic control system to the pilot and air traffic controllers, (2) unequipped simulator wind gust model which led to inadequate training on crosswind training of the pilot. Emphasis on this report includes: pilots training, experience and actions; runway selection and crosswind training; receipt and conveying of wind information by the air traffic controller to the relevant stakeholders; inspection and certification of galley latches and crew seat.
The FAA Advisory Circular 00-57 states that Hazardous Mountain Winds along with their Visual Indicators can enhance the occurrence of mountain wave activity in high altitude terrain (National Transportation Safety Board, 2010). This is due to the increase of wind speeds in high terrain, attaining a minimum of 20 knots at peak elevations. Little variations are noted in the direction of flow of wind across the mountain ridge. These conditions are characterized by airflows over the mountain ridge which produces a harmonic vacillation, a weather condition marked by sinking and rising motions that might extend several miles downstream from the hills ( Keller, Trier, Hall, Sharman, Xu, & Liu, 2015) . AC 00-57 notes that the mountain-wave-related concerns for landings and/or takeoffs encompass loss of directional monitoring on or near the runway (National Transportation Safety Board, 2010). It is proposed according to AC standards that localized winds running on the surface and gusting in excess of fifty knots are not unusual.
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Several studies on mountain waves notable around Colorado have emphasized on extreme windstorm conditions that have resulted in destruction to surface structures around the Boulder area ( Crider, 2010) . Mountain wave wind instances resulting in intermittent sturdy surface winds, however, have not been well researched. As a result, little information is available about the frequency and magnitude of mountain-wave-connected wind occurrences or periods of normal or moderate gustiness in Texas.
Reported documentation indicates that there were no problems with navigational aids in the airline. Also, there were no technical communications issues when the crash occurred. Prior to analyzing the factors contributing to the role of wind in the crash, it is vital to understand the layout plan of the airport as well as the runway ( Keller et al., 2015) . The report dated October 7, 2004 states that DEB airport possessed five runways, each measuring 12,000 feet in a basically south/north orientation along with two others in a primarily west/east orientation.
On the night of the crash, the DEN ATCT in-house controller who certified the crash flight’s takeoff was responsible for all take-offs from runways 25, 34R, 34L (National Transportation Safety Board, 2010). The airplane’s RBDT indicated runway 34R take-off wind data created by LLWAS sensor number 3 (winds running at 27 knots in 270 0 ). These weather conditions were issued to the crash pilots with their departure certification. On the contrary, the AW that was supposed to be indicated above the runway 34 takeoff wind data on the airport’s RBDT at the time of departure clearance ought to have indicated the wind from about 280 0 running at 35 knots, with the gust speed at 40 knots.
Order 7110.11B of DEN ATCT regarding the “Standard Operating Procedure”, section 2-1-6 on the Operational Wind Sources, state that “in reference to departures, runway wind/weather information may be issues after reaffirming centerfield wind in lieu of FAAO 7110.65 (National Transportation Safety Board, 2010). since limited low-level windshear councils were in effect for 34R runway the night of the crash, the provision certifying departure wind data to be given in lieu of centerfield weather or wind information in accordance with the 7110.65 order failed to apply.
The local controller working at DEN ATCT failed to give the AW to the crash pilots when he gave their departure clearance; instead, he gave the runway 34R take-off end wind data, which in this situation was documented and/or reported by the third LLWAS sensor. It was a tradition for DEN ATCT controllers to offer take-off runways ends winds data to any departing aircraft.
The letter given to the airmen offered chances for the dissemination of data that the pilot might have required as concerns the LLWAS, encompassing the possible existence of extra details about wind data and conditions. further, the presence of a letter to the airmen enables ATC facility administrators to certify air traffic controllers to give threshold winds instead or in addition to ASOS wind data if deemed operationally beneficial. It is noteworthy that no such letters addressed to airmen had been available for DEN ATCT (National Transportation Safety Board, 2010). The controllers were rather issuing runway take-off end winds information on the night of Continental Flight 1404’s excursion.
As regards the estimation of wind speed and gusting conditions, the National Transport Services Boards used existing information (measured FDR information as well as the planes acceleration biases taken from the runway or ground path integration) to appraise winds that were present during the crash sequence ( Keller et al., 2015) . Also, Boeing analyzed the wind conditions that were reported during the crash series, using a myriad of wind estimation techniques, which gave outcomes that the winds at the event of the crash varied between 45 and 30 knots from the west. This resulted in an almost straight crosswind for runway 34R along with a crosswind element that varied between 29 and 45 knots.
It is reported that a peak gust of about 45 knots happened at 1818:12, just about the same period the FDR reported the correct rudder pedal starting to move aft from a location about 72% of its available forward acceleration ( Crider, 2010) . This reached an almost neutral position at exactly 1818:13.75.
Various crosswinds departure procedures were established by Continental training administrators, the simulator was developed to replicate the situations (for example, outside temperature, airplane weight, DEN runway 34R, and darkness) of the crash departure (National Transportation Safety Board, 2010). The 5 ATP-ranked members of the examination team then conducted crosswinds departures simulation using left crosswinds of 35, 35, and 0 knots. The pilots were alerted concerning the wind situations before each departure and ranked the sophistication of each departure upon completion. Averagely, the pilots determined these situations to be “very simple” (for the 0-knot crosswind departure), “neither easy or difficult” (for the 25-knot crosswind departure), and “slightly complicated” (for the 35-knot crosswind departure).
References
National Transportation Safety Board. (2010). Aviation accident report: Runway side excursion during attempted takeoff in strong and gusty crosswind conditions – Continetal Airlines Flight 1404.
Keller, T. L., Trier, S. B., Hall, W. D., Sharman, R. D., Xu, M., & Liu, Y. (2015). Lee waves associated with a commercial jetliner accident at Denver International Airport. Journal of Applied Meteorology and Climatology , 54 (7), 1373-1392.
Crider, D. (2010). Determining Ground Winds for Gear-on-the-Ground Accidents Using FDR Data. In AIAA Modeling and Simulation Technologies Conference (p. 6699).
