Page 36 - Feb17TNT

When it comes to getting close to the handbook stopping distances, stick with the methods recommended by the aircraft manufacturer. Company testing found what works most consistently, using average, but aggressive, piloting technique. Use other methods only if you want to act as a test pilot. One of the first requirements is to immediately apply full brakes and hold the pressure, especially if anti-skid equipped. Pumping brakes or delaying application is simply adding unwanted stopping distance.
If the runway is wet, hydroplaning is a definite hazard, but it can be managed by letting the ABS cycle or releasing brake pressure if you feel a lack of deceleration, caused by locked-up wheels. If you see a slick, shiny runway, make your touchdown firm, rather than trying for a soft, roll-on landing. That doesn’t mean pushing the airplane onto the ground at excessive speed, which only encouraging hydroplaning, but rather allowing the tires to sink onto the wet surface with enough force to break through the layer of water.
You’re Down, Now What?
Some aircraft handbooks encourage raising the flaps after touchdown to increase the weight on the wheels, which improves brake effectiveness by removing lift. Most of our airplanes have enough weight to preclude this requirement. If you’re equipped with armed ground spoilers and lift-dump systems, verify they’ve functioned and slowing is normal.
Reverse thrust is a comforting adjunct to wheel brakes, but it must be used appropriately. If in a turboprop, select propeller condition to proper idle setting, move briskly into Beta and increase power as recommended, remembering to come out of reverse before decelerating to a speed that might generate FOD or prop erosion. Steer aggressively to guard against swerving or sliding.
Jets with reverse thrust are also much better equipped to handle a slick runway, but also have limitations to be observed. Excessive reverse on a contaminated surface can create unwanted yaw motion, most particularly with fuselage-mounted engines. Again, be prepared to use aggressive steering and come out of reverse at the first sign of loss of directional control.
Crosswind operation has an effect on stopping distances, in that the benefit of an all-headwind component is lost and braking is slightly compromised if good controls application is not maintained. In most cases, the effect is minor but pilots may be tempted to use extra speed for their approach because they think the crosswind requires added control. Do not pad the numbers excessively, just because a crosswind is present. Most importantly, factor the tailwind or headwind effect into your base leg planning, which can cause you to wind up higher or lower than you might normally be when you roll out onto final.
As you progress down the runway, you should have plenty of stopping distance ahead, because you planned your touchdown for the first portion of the runway and you maintained an approach speed. Keep braking; it’s more efficient to use heavy braking right after touching down than to jam on brakes in a panic as the runway end approaches.
Air traffic controllers seem to be ever-more prone to issue commands to exit at specific taxiways or seek a response about parking while we’re still in the early stages of a landing rollout. If you aren’t able to comply, respond with “Unable” right away and deal with control of the aircraft first. If you were issued a “Land and Hold Short” landing clearance, you are expected to carry it out because you accepted it as issued. The time to refuse LAHSO is when it’s first brought up, not after you’re on the rollout.
As the rollout continues, you may, in the absence of ATC instructions, spare the brakes and reverse thrust to roll out to the end. A longer taxi may better suit your brake and engine cooling concerns. However, we often try for that mid-field turnoff in order to reach a favorite FBO or terminal. Don’t abuse the aircraft and passengers with rough stopping technique, to show off your prowess as a STOL pilot.
B r i n g i n g a n a i r p l a n e d o w n t o a w a l k i s a n o t h e r e x a m p• l e o f proper energy management, begun early in the process so there are no surprises as the runway distance-to-go markers flash past. Done correctly, there should never be a reason for the towercontrollertoquip“speedpermitting,exitattheend.” T&T
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34 • TWIN & TURBINE
February 2017
Leroy Cook has been flying professionally since 1964 and holds ATP/SMEL certification, along with CFI ratings for ASME, In- strument and Glider. He began writing about aviation subjects in 1970 and is the author of thousands of published magazine articles and various books. He is was editor-in-chief of Twin & Turbine from 2011 through 2016.