December 2011 Volume 54 / Number 12
Safety Pilot Landmark Accidents: Owatonna overshoot
A less-than-complete before-landing check
Runway excursions—something other than a planned departure from the pavement during takeoff or landing—are now a focus of safety officials. It seems there has been an increase in the number of accidents and incidents, especially in jet aircraft. Unfortunately, in light aircraft, we’ve been departing runways inappropriately, and with great regularity, all along. While many of these accidents result in little more than damaged egos and hardware, they have the potential to be deadly. Such was the case of a Raytheon Hawker HS125-800 business jet on a Part 135 charter to Owatonna, Minnesota.
The flight departed Atlantic City, New Jersey, on July 31, 2008, with six passengers and two crewmembers at 8:13 a.m. Eastern time. About two and a half hours later the flight was working around a line of severe thunderstorms in the vicinity of Owatonna (OWA).
As the flight came into range of the airport, at 9:37:01 a.m. Central time, the controller provided the Owatonna weather, which was about 20 minutes old. Winds were 320 degrees at 8 knots, visibility 10 miles or more, thunderstorms, scattered clouds at 3,700 feet, overcast at 5,000 feet, and lightning in the distance in all quadrants. At 9:38:07 a.m., the controller advised light precipitation along most of the remaining route with a couple of heavy storm cells about five miles north and northeast of Owatonna.
The crew ran an abbreviated approach briefing and the first officer (FO) tried unsuccessfully to contact the FBO three times regarding fuel and passenger arrangements. The flight intercepted the localizer about eight miles out, and at 9:42 a.m. the captain reported the runway in sight and canceled the IFR flight plan. He then requested the FO try the FBO again—this time the effort was successful.
At 9:42:37 a.m. the before-landing checklist was run and at 9:43:05 a.m., the captain asked the FO to verify the landing configuration.
Raytheon Hawker biz jet lands downwind on a wet runway. After realizing the aircraft will not stop on the remaining runway, the captain elects to go around. The aircraft fails to become
airborne and clips the localizer antenna.
- Wet runway
- Distances in flight manual for wet runway landings may be optimistic
- Cockpit distraction
- Possible crew fatigue
The Hawker touched down on the wet runway at 9:45:04 a.m. at a speed of 122 knots, followed 2.5 seconds later by a sound similar to the air brakes moving to the Open position.
From the NTSB report: “At 9:45:08 a.m., the first officer stated, ‘(We’re) dumped,’ followed immediately by, ‘We’re not dumped.’ [This was referring to the deployment of the lift-dump feature of the air brake and flap systems, which is used to help decelerate the airplane upon landing.] About 1.5 seconds later, the captain replied, ‘No, we’re not,’ and, at the same time, the cockpit voice recorder recorded a sound similar to the air brake handle moving to the Dump position. Ten seconds later, the CVR recorded a sound similar to the air brakes moving to the Shut position. The captain then stated, ‘Flaps,’ and, about the same time, the CVR recorded a sound consistent with increasing engine noise. At 9:45:27 a.m., the captain stated, ‘Here we go…not flyin’…not flyin.’ At 9:45:36 a.m., the CVR recorded an aural warning stating, ‘Bank angle, bank angle.’ The CVR stopped recording at 9:45:45.”
Witnesses noted that the approach looked normal but heard the power increase near the end of the runway. From the NTSB report: “The airplane ran off the runway end at 9:45:29 a.m. and lifted off the ground at 9:45:34 a.m., about 978 feet from the runway end. Subsequently, the airplane collided with the Runway 30 localizer antenna support structure, which was about 1,000 feet from the runway end, and it eventually came to rest in a cornfield beyond a dirt access road that borders the airport, which was about 2,136 feet from the runway end.” The flaps were set to zero, which is not the normal takeoff configuration of 15 degrees. The flight data recorder showed the aircraft pitching up to about 20 degrees and rolling 50 degrees to the right just before impact. There were no survivors.
The 40-year-old captain held a multiengine airline transport pilot certificate, with type ratings in the HS-125 and Learjet series. He had 3,600 total flight hours, with about 1,188 hours in the HS-125 and 874 hours in Learjets. He had flown 110, 24, and 0.3 hours in the 90 days, 30 days, and 24 hours, respectively, before the accident flight and received recurrent training in the Hawker a few months preceding the accident.
The captain typically went to bed around 10 p.m. and was off duty for 72 hours before the day of the accident. The night before the accident, according to his girlfriend, he turned in about midnight (because of a poker game) and awoke the next morning between 4:45 and 5 a.m.
The first officer, age 27, held a commercial pilot certificate with a type rating in the HS-125. He had 1,454 total flight hours, with 297 hours as second in command, most of it in the Hawker. He had flown 86, 27, and 0.3 hours in the 90 days, 30 days, and 24 hours, respectively, before the accident flight. His last Hawker proficiency check occurred eight months earlier.
The first officer also was off duty for 72 hours before the accident. His fiancée noted that he went to bed about 11 p.m. the night before the accident and awoke the next morning around 5 a.m.
This HS 125-800 was built in Great Britain in 1991 and had accumulated about 6,570 hours total flight time. The NTSB found no discrepancies during the accident investigation.
The aircraft is typically landed with flaps set to 45 degrees. A separate handle deploys air brakes in flight. On landing, after touchdown, this same control is used to “dump” lift once the aircraft is on the ground by deploying the air brakes to the ground-only or dump position. The lever is moved to the Open position and then up and over a detent, which increases the flaps to 71 degrees and further extends the air brakes. This system is used in lieu of reverse thrust. The aircraft is also equipped with anti-skid brakes that allow the pilot to apply maximum braking without wheel lockup.
Owatonna’s Runway 30 is 5,500 feet long and 100 feet wide, with a 0.7-percent downslope. The concrete surface was not grooved but crowned to enhance drainage, and has 1,000 feet of grass overrun at each end. The NTSB determined that the runway had excellent drainage and standing water did not cause hydroplaning after recent heavy rains.
Based on witness and ASOS observation and data extracted from the aircraft’s Flight Management System (FMS), the tailwind component was estimated at eight knots. The Hawker came over the threshold on reference speed of 122 knots and touched down 1,128 feet from the threshold at a groundspeed of about 130 knots. At those speeds the friction available on the wet runway was only about 20 to 30 percent of that available on a dry runway.
Stopping distance on dry runways is one thing; it’s quite different when wet. The computed numbers also depend on who’s doing the figuring and their assumptions. The Airplane Flight Manual (AFM) landing distance data are based on the air brakes moving to the Open position 0.56 second after touchdown and on the lift-dump system being engaged at the same time. It takes about two seconds for the lift-dump system to fully deploy. On the accident flight, the air brakes were moved to the Open position about 4.1 seconds after touchdown, and the lift-dump system engaged about 8.9 seconds after touchdown.
The NTSB went into great detail on how the landing distances were derived and noted that the British formula is more optimistic than the FAR Part 25 formula used in the certification of U.S. aircraft. The actual braking coefficients on wet, ungrooved runways may be less than what the British certification tests predicted. It is improbable that any calculations would exactly duplicate the actual conditions.
According to the AFM, with a landing speed of 122 knots, the no-wind landing distance on a dry runway would have been about 4,216 feet, 3,966 feet with a 10-knot headwind, and 5,059 feet with a 10-knot tailwind component. No correction for a wet runway is provided in the manual. The NTSB report: “However, if the destination runway was expected to be wet or slippery, pilots were trained to add a 15-percent safety margin to the required factored dry-runway landing distance.” Based on this, the Hawker would have gone off the end of the runway between 27 and 37 knots, coming to a stop in the grass 100 to 300 feet off the end. The onboard handheld computers would have calculated landing distance at 3,940 feet with a tailwind and wet runway—obviously a bit optimistic.
The crew did not perform a landing distance assessment prior to landing, nor did the FAA require it. However, FAR 91.103, Preflight Action, does require the pilot to review runway lengths with takeoff and landing distance information.
“The National Transportation Safety Board determines that the probable cause of this accident was the captain’s decision to attempt a go-around late in the landing roll with insufficient runway remaining. Contributing to the accident were (1) the pilots’ poor crew coordination and lack of cockpit discipline; (2) fatigue, which likely impaired both pilots’ performance; and (3) the failure of the Federal Aviation Administration to require crew resource management training and standard operating procedures for Part 135 operators.”
The CVR records a less-than-complete before-landing check with no discussion relative to wind or runway conditions, which to me is the real issue. Had the crew landed into the wind it would have been normal. Nonpertinent discussion with the FBO distracted the crew at a critical time when the cockpit should have been sterile. Convenience to get the ground transport arranged or the fuel truck out just a little faster pales in comparison to landing safely. Aviate first, communicate last.
After the Southwest Airlines 1248 accident at Midway (see “Safety Pilot Landmark Accidents: Overrun!” December 2008 AOPA Pilot), the NTSB recommended factoring the landing distance. In that accident the onboard computers optimistically misled the crew, and the captain delayed applying reverse thrust—just as this captain was slower than the AFM required.
The NTSB mentioned fatigue as a factor, with the captain having only about five hours of sleep. Both crewmembers had been off for several days and knew they would have an early start the next day. Fatigue regulatory issues abound, but not in this case. The responsibility to get proper sleep rested solely with the crew. Plan on getting at least seven to eight hours of solid sleep before an early morning flight and adjust your schedule accordingly—i.e., no poker games!
It’s wishful thinking to believe that most pilots will consistently perform as well as test pilots. In real-world flight operations we don’t. To meet the numbers in the AFM, all of the conditions must be met. Requiring manual deployment of the dump system one-half second after touchdown is stretching human performance limits.
The NTSB noted that current regulations do not require landing-distance assessments, conducted in flight, to determine whether a successful landing can be made under existing conditions—nor do they specify minimum safety margins for such assessments. The FAA is reviewing this currently. Landing data for other than dry runways is currently calculated, rather than flight-tested. For light aircraft the Air Safety Institute recommends adding 50 percent to the POH takeoff and landing distance over a 50-foot obstacle and, on wet runways, to double the estimated distances.
Absence of an accident doesn’t necessarily mean you’re doing it right.
This charter company had a perfect record over a 10-year period, but absence of an accident doesn’t necessarily mean you’re doing it right. It just means all the links in the accident chain haven’t connected—yet. And circumstances are such that they may never do so, but in aviation safety the best adage is to remember that Murphy, of Murphy’s Law fame, was an optimist.
Bruce Landsberg heads the AOPA Foundation in its mission to preserve and protect GA.