Crosswind landings at at Düsseldorf involving Boeing 777, Boeing 767, Boeing 757, and Airbus A330
O’Hare International Airport is scheduled to eliminate two of its once very popular diagonal runways 14L/32R and 14R/32L. Runway 14L/32R was closed Wednesday night. A large part of the reason for the elimination of the runways is to avoid intersecting runways in the new multiple parallel configuration at O’Hare International Airport. Officials say the new configuration will allow more planes to land and takeoff and will allow the airport to accommodate more flights in a given time period.
Without the diagonal runways, which are aligned northwest to southeast, the airport configuration will no longer be available to land aircraft into strong southeast or south winds, or take off into strong northwest or north winds. This will result in more crosswind landings and takeoffs. Pilots will be forced to use extra skills that require them to maneuver the aircraft in a certain way to keep the aircraft moving along the center of the runway. Pilots must use a crabbed approach or sideslip approach when landing in high crosswinds. In the crabbed approach, pilots yaw the nose of the aircraft slightly against the wind or into the wind to correct the drift. In the sideslip approach, pilots roll the aircraft by slightly lowering the wing on the side of the wind source, which puts less pushing airflow under that wing that could push the aircraft off center of the runway. In 30 knot crosswinds, pilots might be required to combine the crab angle and the sideslip (banking angle) techniques.
The Flight Operations manual by Airbus reports that adverse wind conditions (i.e., strong crosswinds, tailwinds and wind shear) are involved in 33% of approach-and-landing accidents. Crosswind in association with runway condition is a circumstantial factor in nearly 70% of runway excursion events, and 85% of crosswind incidents and accidents occur at landing.
On a runway contaminated with standing water, slush, snow or ice, a maximum recommended maximum crosswind is defined depending on:
• Reported braking action (if available), or
• Reported runway friction coefficient (if available), or
• Equivalent runway condition (if braking action and runway friction coefficient are not available).
Runway conditions that affect braking action include slush cover, dry snow cover, wet snow cover, and standing water or wet pavement with risk of hydroplaning.
In heavy rain or heavy wet snow conditions, runway conditions could cause maximum recommended crosswind conditions as low as 15 knots or 17 mph. In good runway conditions (a dry runway without risk of hydroplaning), Airbus recommends a maximum crosswind of 30 knots or 34 mph.
To minimize the risk of hydroplaning on touchdown, Airbus recommends pilots “perform a firm touchdown when landing on a contaminated runway.” Also, on a contaminated runway, the aircraft tends to travel along the runway centerline with the existing crab angle. In other words, it tends to slide off of the center line and possibly off the runway, if not corrected. Also, as the aircraft touches down, the side force created by the crosswind component on the fuselage and fin tends to make the aircraft skid sideways (downwind) off the centerline.
Winters in Chicago are commonly associated with very strong northwest and north winds, which would apply strong crosswinds to all of the new parallel runways. The runways are also subject to at least slight contamination by snow, ice and water with even the best runway maintenance.
Airbus Describes the Factors Involved in Crosswind-Landing Incidents and Accidents that often are involved in crosswind-landing incidents and accidents:
• Failure to recognize changes in landing data over time (i.e., wind direction shift, wind velocity or gust increase)
• Reluctance to divert to an airport with less crosswind conditions
• Low visibility, that makes runway alignment at touchdown more difficult
• Lack of time to observe, evaluate and control the aircraft attitude and flight path in a highly dynamic situation
• Wet or contaminated runways.
In consideration of the elimination of the diagonal runways in the modernized O’Hare International Airport, the questions to ask are …
Will more aircraft slide off runways after touchdown in strong crosswinds?
Will the risk of crash landings be increased in strong crosswinds?
Will more aircraft landing gear be damaged because of hard landings?
Will O’Hare International Airport be closed more often in strong crosswind conditions without the option of using 14L/32R or 14R/32L?
Does the elimination of the diagonal runways result in less safety options and higher exposure of aircraft in potential wind shear situations.
Crosswind Landings at Düsseldorf on an icy runway featuring the following aircraft: Boeing 777, Boeing 737, Boeing 757, Airbus A340, Airbus A330, Airbus A321.
Multiple Aborted Landings: Dangerous Crosswind Landings during a Storm at Düsseldorf.
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