Industry Blog: Have a Plan To Prevent Runway Excursions
Runway excursions are the most common type of business aviation accident. Nearly one-third of all business aviation accidents involve an aircraft overrunning or veering off a runway during takeoff or landing, according to the National Business Aviation Association. Most troubling, these events are often preventable when flight crews understand the well-known risks and adopt best practices to mitigate them.
Considered “a towering concern,” runway excursions—for the fourth consecutive year—landed on the NBAA Safety Committee’s annual list of Top Safety Focus Areas. Most runway excursions are nonfatal but have the potential to cause great harm and damage. Industry-wide, according to the NBAA, these events cost nearly $900 million in injuries and damages per year.
The most recent business aviation runway overrun involved a Beechjet 400A at Cleveland Burke-Lakefront Airport on February 4. In this case, the aircraft stopped safely on the Engineered Material Arresting System (EMAS) in the runway safety area, just short of Lake Erie. The FAA credited this as the 13th EMAS “save” preventing a serious runway overrun.
There are a number of industry best practices and resources available to prevent runway excursions. For this discussion, let’s assume most of the preflight performance planning is complete and focus on actually flying the aircraft.
One quick planning note: groundspeed zero is where contingencies such as alternates, the use of “wet” data, and lighter operating weights should be considered. It might also be prudent, at this point, to change the destination to a better-suited airport. A number of business aviation runway excursion accidents have occurred at smaller secondary airports when a larger, better equipped airport was nearby. Choosing safety over convenience is a good decision.
Once at the controls, pilots face several challenges. Most jet operators use some method of optimized takeoff performance calculations, but it’s good to know exactly how these numbers are derived and the safety margins afforded. During takeoff, the most common factors associated with runway excursions are a rejected takeoff at or above V1 or a loss of directional control. Weather and runway conditions further compound these risks.
En route is a time to further refine your plan to account for changes in weather and runway conditions. At a minimum, before beginning the approach briefing (before the top of descent) flight crews should have calculated the required runway length at the time of landing and determine a “go-around point,” the latest point on the runway to touchdown.
One major challenge is operating at an airport without the capability to report weather or runway conditions. In this case, crews should plan for the worst. If there is rain in the area, use wet runway data. If it is raining at the airport, assume that there is water on the runway. If there is any doubt, use the most conservative condition that requires the longest landing distance.
Up until this point, much of the focus has been on some pretty precise planning. Now it’s time to execute, during the approach and landing phases. This is where the proverbial rubber hits the runway. According to the FAA, several factors cause landing overrun excursions. All of these are cumulative and are under the direct control of the pilot:
Unstable Approach—Safe landings begin long before the touchdown. Adherence to stabilized approach criteria is a must. If the approach becomes destabilized, go around.
Threshold crossing height (TCH)—Most aircraft are certified with a TCH of 50 feet. For every 10 feet above the TCH, landing distance is increased by 200 feet.
Extended flare or long landing—Remember, braking on the ground is far more effective than attempting to bleed off energy in the flare. Most landing distances provided by commercial products are predicated on touching down by a specific point on the runway (for example, 1,500 feet); landing beyond this point invalidates any calculated landing distances.
High touchdown speed—A 10 percent increase in airspeed at touchdown increases the landing distance by 20 percent. A tailwind has a similar effect; for each 10 knots of tailwind, landing distance is increased by 21 percent.
Delay in deploying deceleration devices—Thrust reversers, ground spoilers, and brakes help decelerate the aircraft during the landing roll. Any delay in deploying these devices will affect landing distance. A two-second delay in deploying thrust reversers can add 200 feet to the landing distance. Less than maximum braking will generally add another 20 percent to the total. Boeing now recommends crews “brake for safety—not comfort.”
Runway excursions are a very high-risk event. Anytime an airliner or business jet goes “off-roading,” all bets are off. The potential for injury or death is unacceptably high. Pilots must understand aircraft performance and come up with a solid game plan to mitigate the risks associated with a runway excursion.