LOSS OF DIRECTIONAL CONTROL ON RUNWAY
Acknowledgements: Thomas P. Turner (Mastery Flight Training Inc.)
(Ed. Note: The following excerpt is taken from Tom’s weekly lesson, received today – thanks Tom!)
“Just since last week’s lessons, in the FAA Preliminary Accident Reports:
· A Honda Jet “veered off the runway through grass while landing….”
· A Taylor-Craft “landed and was blown off the runway….”
· A Piper Cherokee “veered off the runway into the grass….”
· A Piper Seneca “veered off the runway into the grass….”
· A Beech Super King Air blew a “tire on landing, aircraft then veered off the runway….”
· A Piper Seneca “veered off the side of the runway during landing….”
· A Cessna 172 “was cleared for takeoff, veered left into the grass….”
· A Republic Sea-Bee “went off the runway into a ditch….”
· An Evangel Angel tricycle-gear twin “ground looped upon landing and struck runway lights….”
· A Taylor-Craft “veered off the runway and flipped over….”
· A Kolb Mark III “on landing veered off the right side of the runway into the grass….”
· A Gippsland GA8 “blew a tire on landing and veered off the side of the runway….”
· A Piper Cherokee “struck a snow bank on landing and veered off the runway….”
· A Piper Cherokee “damaged a runway light” while landing.
· A Bellanca Citabria “went off the runway into a lake and submerged in water….”
· A Piper Pawnee “lost control on departure with a glider attached, went off the side of the runway….”
This tells us two things:
(1) Someone in the FAA Safety Centre really likes the word “veer”!
(2) We’re having trouble maintaining runway alignment and aircraft control, especially during landing.
That’s 16 Loss of Directional Control on Runway(LODC-R) events reported since last Wednesday. Take the two blown tires off the list (we’ll assume the tires blew and caused the loss of directional control, not the other way around), and there are still 14 events in the last eight days of reports. It seems as though this is common this time of year, as many Northern Hemisphere pilots are getting back into flying after a long winter at the same time the winds tend to increase with the change in seasons.
In the eyes of our passengers the measure of a pilot seems to be how smoothly he or she lands the airplane. They feel a good landing means a good pilot, but a firm or bounced touchdown negates everything the pilot did to that point! Somewhere between the two extremes (that the landing needs to be glassy smooth or it may destroy the airplane, but it’s okay as long as no one is crippled!) lies the reality: we need to land with a level of aircraft command.
How do we avoidloss of control on the runway (LODC-R) or runway overruns? Every situation is different, but you’ll improve your precision and reduce your chances of joining the list of “on landing….” by doing the following:
· Taxi with the nosewheel on the centre-line. This reinforces your perception of deviationsfrom runway directional control. Discipline here will pay dividends when you need to be making instinctive control inputs during take-off and landing.
· Use the correct crosswind controls during ground operations. This makes instinctive your input of proper corrections during crosswind landings… even when winds are less than when you think you need the crosswind controls.
· Fly at the correct speeds. Trying to land too fast - a common mistake- makes it harder to land accurately in the touchdown zone, thus making a runway overrun or the need to apply heavy braking (leading to nosing over) more likely. Even in strong gusts you don’t need to add that much speed; the convention is to add one-half the gust value. The result is much less added speed than you might think. For example:
· if landing a Cessna 172 in winds at 15 gusting to 22 knots, the gust factor is seven (22-15=7) and half that is three and a half. So your final approach speed increases from, say, 65 knots to 69 knots… not 75 knots, or 82 knots, or 90 knots, or some other amount that makes it more likely you’ll land long or run off the end of the runway.
· In a mid-weight Beech 58 Baron landing in that same gust factor increases over the threshold speed from 91 to 95 knots.
· In a Citation the increase is almost negligible as a percentage of VREF(final approach reference) speed.
· If you receive Pilot Reports of wind shear with airspeed fluctuations on final approach (e.g., “airspeed varies +15 knots”) you might add as much as that variation amount to your final approach speed, knowing you still have to dissipate it in the final moments before touchdown. If that speed adjustment is more than about 20% of your airplane’s final approach speed you probably need to land somewhere else!. If the report comes from an aircraft larger than the one you are flying treat wind shear PIREPs the same as you’d treat a turbulence or icing PIREP from a larger aircraft—expect that the indications will be worse for you.
· To be prepared for those speeds, practice and retain proficiency and comfort flying at low speeds and high angles of attack. Practice “slow flight” or, as we used to call it “flight at minimum controllable airspeed” so you not only apply controls in the proper direction, you also apply them in the correct amount… without having to think about it.
· Be established on speed, inconfiguration, onglidepath to your planned touchdown zone, and inalignment with the runway and the runway centre-line between your main wheels within about 400 feet of the ground, or certainly before you cross the runway threshold… or go around without question or delay.
· Fly enough to know your capabilities, and your limitations. In most LODC-R mishaps the crosswind component is far below the airplane’s maximum demonstrated amount. In most LODC-R events the crosswind component is less than 10 knots. In almost all cases it’s a pilot issue, not an airplane issue. If you’ve not flown crosswinds recently, reduce the amount of crosswind you’re willing to accept.
· Discipline yourself towardexcellence. Back it up with demonstrated proficiency. And use good judgment to avoid situations you knoware beyond your current capability.
Although it doesn’t have the appeal (if that’s the right word) of thunderstorms or ice or low clouds and fog when discussion aviation weather hazards, the wind, especially wind during take-off and landing, is the single largest weather hazard to non-transport category airplanes, according to the accident record.
Most pilot training textshome in on the stick-and-rudder skills needed to maintain runway alignment in a crosswind. That’s absolutely essential, and crosswind control should be at the centre of all your recurrent training. But the industry is remiss in omitting the single biggest factorin the success of a crosswind landing - the decision whether or not to try it in the first place.
Take-offs are optional. Landings are not. However, landing at any one location, or on a specific runway, is optional. Make a conscious decision to accept or rejecta landing by figuring the crosswind component before accepting an approach or entering the pattern/circuit. Most LODC (Loss of Directional Control) on landing events occur, in fact, with reported surface winds reported below 10 knots.
So why do we lose directional control in such relatively low surface winds? I suspect that:
· We’re not as current in crosswind landings as we think we are.
· It doesn’t take much changefor a crosswind to swing around and include a tailwind component, which is even more destabilising to many airplanes.
· Some pilots may be too rushedto fly to a landing into the wind when their route of flight is nearly straight in to a more convenient, if not wind-aligned, runway.
· Others may not be assertive or confident enoughto change runways when ATC assigns a runway the pilot would not chose on his/her own.
· Flight instructors may notbe emphasising good crosswind technique, including “flying” the airplane all the way to the completion of the landing roll.
· Many pilots may not botherto consider the effect of wind as part of their arrival briefing.
How can we address these possibilities?
· Renewed emphasis on proper techniquein flight instruction for pilots at all levels,
· Having the confidence to refusea runway when the winds do not favour its use…even if others are using it or if initially assigned by ATC.
This means consciously estimating the crosswind as part of your arrival self-brief, and developing the willingness to request another runway or even fly to a more favourable airport”.