Rubber and Runways

Sometimes tires and pavement just dont want to be together. Heres how to make em

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The moment of truth often comes at the end of a flight, when the rubber reaches for the runway for the first time. All too often, thats when the ride begins. Watch the traffic at any airport for any length of time and youre sure to see ballooning and bouncing – control errors when the airplane is in its most vulnerable state.

Ballooning and bouncing are related in that they are both caused by over-controlling or misjudging the descent rate. They can happen in a hurry. Lower the flaps too late or flare before lift has decreased enough and you balloon upward. Similarly, you can expect a bounce if you flare too late or otherwise hit the runway with too much energy. Each problem has a solution thats fairly simple to understand, but sometimes complicated to apply.

If you raise the angle of attack to the landing attitude before lift has decreased enough to land, youre in balloon territory. Just how much unwanted altitude you gain at the wrong time will depend largely on the airspeed or how rapidly the pitch attitude is increased.

In a ballooned landing, your height above the runway increases and, in extreme cases, you may be on the verge of stalling. Maybe someone in the right seat will take over, maybe not. The balloon can become even more serious, however, if you become distracted to the point you remove crosswind controls. If your pitch angle is more nose-up than the landing attitude and youve lost your crosswind correction, you might want to consider going around for another try.

A bounced landing can result when the flare-out has been made too slowly or too late. If the nose gear hits first, the airplane will bounce. In a taildragger, if the main gear hits first and controls are not in place for a wheel landing, the airplanes inertia will force the tail down, which increases the angle of attack. Combine that with spring-steel gear legs, and the bounces can be impressive. Bounces can also happen with the airplane at roughly the right attitude but carrying too much energy, either because the airspeed is high or the descent rate is too much.

In one accident in Columbia, Tenn., a student pilot landing a Piper Warrior bounced three times and went off the side of the runway, due to his overcompensation for drift. The aircraft struck taxi lights, runway lights and a taxiway sign before coming to rest on the grass on the left side of the runway.

Of course the force with which the aircraft strikes the runway (and how the pilot used the elevators at that instant) will determine how high it will go. You can count it a severe bounce if you have lost your crosswind correction or if the pitch attitude becomes more nose-up than the landing attitude. Although pilots waiting in the run-up area may score you on the height of your bounce, control is a much more important factor.

Pilots usually apply excessive back pressure when they realize the airplane is not in the proper landing attitude. Too soon and they balloon, too late and they bounce. A nasty bounce can also occur when an aircraft is dropped in from too high a flare-out.

High-Time Folks, Too
Bounced landings just dont bite student pilots. One pilot with a ATP rating and some 25,000 hours was doing some VFR night training in his newly purchased Beech B55 Baron. Aboard with him were four passengers, flying out of Morganton, N.C.

During the accident flight, the pilot entered the traffic pattern and configured the airplane for landing. While landing, the airplane touched down nosewheel first, bounced and began to porpoise.

Following the second bounce, the airplane pitched up and the pilot started a go-around. However, the airplane bounced a third time and the cabin door popped open. The right front seat passenger attempted to hold the door closed as the pilot continued the go-around.

The airplane remained airborne – between 6 and 15 feet high – until it collided with trees beyond the departure end of the runway. It then came to rest inverted.

Examination of the engines, propellers and flight controls showed no evidence of malfunction or pre-impact failure. Calculations showed that, at the time of the accident, the gross weight was over the maximum limit and the center of gravity was 1.56 inches behind the aft limit. The Pilot Operating Handbook indicated that performance would be reduced with an open cabin door. The pilot had flown an estimated nine hours in the airplane since he purchased it.

To top it off, the pilot, who had delivered the airplane to the new owner and had flown with him several times, told investigators the new owner usually flew about 20 knots fast on final approach and had a tendency to flare late on landing.

In its official findings, the NTSB blamed the pilots delay in initiating a go-around (aborted landing), which resulted in his failure to obtain/maintain sufficient altitude or clearance from trees beyond the end of the runway. Contributing factors were the improper weight and balance and his improper recovery from a bounced landing.

Correcting the Bounce
The corrective action for a bounce depends to some extent on how severe the situation is. In general, its the same corrective action for ballooning.

One rule to paste up on the panel: Any time you experience a bounce or balloon of more than 10 feet, apply power and execute a go-around.

Some pilots may feel thats a conservative approach, and depending on the wind, runway length and pilot proficiency, it may very well be. If the bounce or ballooned landing is minor, meaning it rebounds only a few feet up and you havent developed an extreme change of pitch attitude, the landing can usually be salvaged. The pilot needs to maintain or re-establish directional control and apply power to cushion the landing. The pitch attitude is smoothly adjusted to the landing attitude just prior to touchdown.

Recovering by applying a bit of power and easing the airplane to the ground takes some finesse – and a fair amount of runway. There are some highly proficient pilots who can judge height to a gnats eyebrow who can recover from just about any bounce. But if youre one of them, you probably dont get into too many bounces in the first place.

The crosswind correction has to be considered one of the most important parts of the landing attitude. Many pilots confront a balloon or bounce by focusing their attention on their height above the runway. What they forget is that once the bounce occurs the wings will almost always be level and the airplane will begin to drift away from the runway centerline.

Students and pilots with waning proficiency show a couple of different patterns when it comes to applying the proper landing technique. Some try to fight the wind. They first turn into it until they are aligned with the runway centerline, then turn in the opposite direction to keep the runway lined-up. The whole procedure goes over again. From the ground it looks like a series of S-turns on final.

Others understand what they are supposed to do. They hold a crab into the wind, keeping their course to the runway. But as soon as they get near the ground all the good control inputs go away. The cross-controlled attitude wobbles, flare at the proper altitude is forgotten and the main wheel on the side into the wind doesnt come even close to touching down first.

In both cases, a bounce or balloon will almost certainly cause the airplane to lose proper orientation with the runway unless the wind is dead calm or straight down the centerline. In those cases, there should be no indecision. Execute the go-around.

As you scan through landing accident reports, it becomes painfully clear that many landing accidents would not happen but for the pilots failure to react effectively to a balloon or a bounce. If the pilot allows the airplanes pitch attitude to exceed the touchdown attitude a number of things happen. The airspeed is decreasing rapidly, control response is fading away and the nose should be lowered. If you lower the nose abruptly an extreme amount, you can expect a hard landing or porpoise, and aircraft damage is very likely. Since the positive lift is decreased – even for a moment -by the change in angle-of-attack, the rate of descent is increased. If you are close to the runway with this major loss of lift, the landing will be a jolt.

The Porpoise
In any landing – crosswind or not – porpoising can result in a violent, unstable condition, where the aircraft bounces back and forth between the nosewheel (or tailwheel) and the main gear after initial touchdown.

The pinball effect is mostly caused by an incorrect landing attitude at the time of first ground contact. In a trike, the nosewheel makes contact with the runway before the main gear touches down. It all starts with an incorrect landing attitude and too much airspeed.

What usually happens is that the pilot attempts to force the airplane to land. The nose bounces up and the pilot attempts to counteract each bounce with an opposite control movement. Wrong move. The pilots reaction time means his actions cant possibly match the airplanes movements. The porpoising will be aggravated because of the pilot-induced oscillations. Repeated heavy impacts of the aircraft on the ground during the porpoising can easily result in structural damage to the engine mounts, airframe and landing gear.

If a porpoise starts, the initial response is essentially the same as any other bounce or balloon. Immediately and smoothly establish the normal landing attitude and add a bit of power. The power will get back flying speed and control effectiveness, allowing the aircraft to get airborne again, eliminating further bouncing on the runway.

Once out of the porpoise condition, decide if there is enough runway left for a normal landing or go-around.

To go around or not to go around is one of a pilots most critical airborne decisions. It generally isnt a major problem when you are on an approach. Its a bit more problematic to execute a go-around from the final approach glide, flare or bounce. The trick is to recognize a poor landing early and start the go-around before the airplane gets to a critically bad configuration. Its a lot safer and easier than allowing a situation to develop that can get out of control.

Go-arounds should generally follow this pattern, unless your POH says otherwise: First, smoothly add full power (with carburetor heat off) and maintain directional control. Re-trim, as required. Maintain level flight and retract the flaps, as necessary, then the landing gear. Continue to maintain straight and level flight until you accelerate to climb speed, then pitch up for a positive rate of climb.

Landing Attitude
Crucial to getting the airplane to land properly is establishing the correct landing attitude. Surprisingly, many pilots dont really know what this attitude is.

Weve said that a balloon or a bounce can become severe, regardless of your height above the runway, if the pilot allows the pitch attitude to increase to more than the landing attitude. And if this does happen, the pitch attitude must be decreased. The question many people have trouble with is determining how much.

The easiest way to familiarize yourself with the proper recovery attitude might be to practice some slow flight. It means flying level, at minimum controllable airspeed in the landing configuration. This slow flight attitude is between the nose-high landing attitude and level pitch attitude in most airplanes, and usually closer to the level pitch attitude.

Heres where you can get some extra value out of your flight review. Or, if thats too far off, and you are a bit rusty on slow flight, get with your local CFI. Its good insurance.

Next time you bounce or balloon and the pitch attitude has exceeded the landing attitude, the recovery out of this situation is to simultaneously add full power and release some of the elevator back pressure. Then smoothly change the pitch attitude to the slow-flight attitude to regain speed.

If you can use engine power during a balloon or bounce, the airplanes nose should never be pointed down any lower than a level pitch attitude. A lot of precious runway can be used up when recovering from poor landings. Skilled controlled responses and large power changes are necessary to recover from one of these. The most prudent action often is to abandon the landing attempt and make a go-around, but there are other choices – if you have the skill to use them.