AINsight: What’s Going On with Bizav Runway Excursions?

Runway excursions account for nearly one-third of all business aviation accidents—lately, these events are becoming all too common. Most troubling, barring a mechanical failure, these events are preventable when pilots understand the well-known risks and adopt best practices to mitigate these risks.

According to the NBAA Safety Committee, runway excursions are a “towering concern” and have been cemented on its list of top safety focus areas for nearly a decade. The FAA, NTSB, Canada’s TSB, and other aviation agencies have all expressed concerns about runway safety, including runway excursions and incursions.

I, too, am concerned. What is going on?

Last month, I wrote about high-energy approaches after two business jets on one calendar day overran runways—only to be saved by EMAS. And one day before that blog was published, a Cessna Citation CJ4 overran a runway in Kentucky, broke through a fence, crossed a highway, and hit a house. Three weeks later, a CJ3 overran a runway—this time coming to rest on a golf course.

Let’s look at these two events and revisit other topics such as preflight planning, in-flight assessments, decision-making, and landing techniques. In addition, we will dig deeper into industry best practices, such as guidance from the CitationJet Pilots Association (CJP).

Off-road Citation Jets in Kentucky

The CJ4 was substantially damaged when it overran the runway at Kentucky’s Mayfield Graves County Airport (M25) on September 18. The jet was unable to stop on the 5,002-foot runway and hit a house 708 feet past the end of the runway. The aircraft had substantial damage to its fuselage, wings, and landing gear; there were no injuries.

The FAA and NTSB are investigating the accident. Preliminary reports list the event as a runway excursion during landing. ADS-B data indicated a ground speed of 213 knots at 1,300 feet and 1.64 miles from the runway. The aircraft was both high and fast, suggesting an unstable approach and possible long touchdown. Weather at the time of the accident was reported as clear skies, 10 miles visibility, and light winds (less than 3 knots). 

On October 7—less than a month later—the CJ3 overran 3,580-foot-long Runway 33 at Bowman Field (KLOU) in Louisville, Kentucky. The aircraft departed the paved surface of the runway, crashed through an airport fence, and came to rest on an adjacent public golf course. There were no injuries to the four occupants of the aircraft, but the aircraft sustained substantial damage to its nose gear and undercarriage.

According to reports, ADS-B data indicated that the aircraft left the end of the runway at 55 knots ground speed. Weather reported at the time of the event was IMC with a 900-foot broken ceiling, 2.5 miles visibility with heavy rain (+RA) and a direct tailwind of 8 knots.

Resources

As an operator of a turbine-powered business aircraft, it is recommended to download and review the following documents: FAA Advisory Circular 91-79B “Aircraft Landing Performance and Runway Excursion Mitigation,” FAA SAFO 19001 “Landing Performance Assessments at Time of Arrival,” and NBAA’s “Reducing Runway Excursions in Business Aviation,” a high-level guide on mitigating risks.

Another top recommendation is to join the owner-pilot group or association for your aircraft type. As an example, CJP offers specific standard operating procedures (SOPs) for pilots of Citations. Likewise, the Honda Jet Owners and Pilots Association provides solid guidance on runway safety to its membership.

In addition, depending on the type of operation, pilots must be familiar with the applicable regulations.

Step 1: Preflight Planning

In general, regulators require pilots during preflight planning to ensure that there will be adequate runway available for landing at the destination. In the U.S., preflight planning is covered by FARs 91.1037, 135.385, and 121.195.

For dispatch purposes, if operating a large transport-category turbine-powered aircraft “for hire,” the landing distance can be no greater than 60 percent of the available runway. If that runway is wet or slippery, add another 15 percent to the aircraft’s landing distance. These distances are calculated using the expected runway condition at the time of arrival, based on forecast conditions.

Pilots must understand the nuances (unfactored, factored, wet, etc.) of certified landing distance charts and tables contained in the aircraft flight manual (AFM).

As an example, wet landing distances are obtained through a mathematical calculation using a factor of 1.15 (15 percent)—there are no flight test validations here.

According to AC 91-79B, if there is moderate or heavy rain, use extreme caution. Analysis of runway excursions in moderate or heavy rain resulted in significantly lower braking coefficients than would be expected for “wet” runways. These events occurred on both grooved and non-grooved runways.

Here’s another caveat from CJP: be skeptical. These certified landing distances are based on the best landings performed by a test pilot, with no variation from speed or glide path, and maximum braking using new tires and brakes. Small variations in pilot technique can add hundreds or even thousands of feet to the landing distance.

Step 2: Landing Distance at Time of Arrival

Before landing, it is recommended—and required by some operators—that pilots assess the landing distance at the time of arrival. This guidance is independent of the preflight landing distance planning requirements.

SAFO 19001 provides guidance to operators on landing performance assessments at time of arrival. The document was published to assist operators in developing methods to ensure sufficient landing distance exists to safely make a full stop landing.

This assessment is based on real-time conditions to include runway contaminants, winds, speed additives, and touchdown points. It is recommended that the flight crew determine the most accurate landing performance assessment at a point in time to obtain the most current meteorological and runway surface conditions.

CJP Safe to Land

Next, using elements of CJP’s “Safe to Land” initiative, I will analyze the recent CJ3 overrun at KLOU. Safe to Land is the result of an extensive study conducted by CJP and the Presage Group to refine stabilized approach criteria and landing procedures to prevent runway excursions. This guidance includes approach gates for approach stability (1,000 and 500 feet) and a go-around decision point (200 feet) during the approach, and establishing a touchdown point limit from the runway threshold (floating) and a lateral limit from the runway centerline (drifting).

For most Part 91 operators, CJP SOPs may be more restrictive. As an example, CJP recommends computing takeoff and landing data before every takeoff and landing using the manufacturer’s performance data, and observing the following guidelines to provide adequate safety margins:

• Count no performance benefit for headwinds.

• If any tailwind is expected to exist, compute the penalty using 10 knots of tailwind component (do not interpolate).

Additionally, for landing, the computed required field length must be less than or equal to 80% of available landing distance if an electronic or visual descent path indicator is available to the landing runway, or less than or equal to 60% of available landing distance if no electronic or visual descent path indicator is available to the landing runway.

This accounts for variances in pilot performance based on the availability of vertical guidance to the touchdown zone. Safe to Land also requires pilots to calculate a touchdown point limit – any anticipated landing beyond this point requires a go-around.

Case Study: CitationJet CJ3 flight

Data for two runways are analyzed based on weather and the approach capabilities of each runway. In IMC, KLOU has two runways available—Runway 24 and 33—and each has an RNAV approach with a PAPI. Landing distance available (LDA) for Runway 24 is 3,856 feet, while the LDA for Runway 33 is 3,125 feet.

As previously stated, the weather at the time of the overrun event was 900 broken, 2.5 miles visibility, heavy rain, and winds of 150 at 8 knots.

In this exercise, the data presented in the following tables is based on a standard day (15 degrees C) with a dry runway. A wet runway would require an additional 15% of landing distance. Heavy rain with standing water on the runway would require significantly more distance to stop.

This exercise illustrates the importance of analyzing landing performance on every flight, before beginning an approach and landing. Plans often change—runways can close, approach aids can go out of service, and the weather may deteriorate. Pilots must adapt to these changes, make smart decisions, and consider diverting to an alternate airport if the numbers don’t add up.

Pilot Actions

According to AC 91-79B, several factors contribute to 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. Operators should have a “no-fault go-around policy.”

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. Braking on the ground is far more effective than attempting to bleed off energy in the flare. Most landing distances provided by OEMs are predicated on touching down by a specific point on the runway. 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.

Investigations into the two CJ overruns are currently underway. Final reports are typically published within 12 months.

Soon, I will write my 100th AINsight blog about safety events in business aviation, with an emphasis on reducing risk. Unfortunately, runway excursions happen all too frequently, and one-in-five of my blogs are related to reducing approach and landing accidents (below is a listing of some past topics). Runway excursions are preventable; following SOPs such as CJP’s Safe to Land initiative makes sense, increasing the margin of safety and helping eliminate these accidents.  

Past blogs:

Runway excursion accident (Citation Latitude): AINsight: Do I Need To Go Around?

Runway excursions on takeoff: AINsight: Runway Excursions and Crosswind Takeoffs

Runway excursions on landing: AINsight: Runway Excursions and Crosswind Landings

Runway excursion prevention/planning: AINsight: Preventing Runway Excursions a Complex Task and AINsight: Have a Plan To Prevent Runway Excursions.

The opinions expressed in this column are those of the author and not necessarily endorsed by AIN Media Group.