Section=Getintro
Feb. 22, 2007
Interactive Quiz #117:
Why Make Bad Landings?
Would you rather bounce in a quiz or on real pavement? Let's turn base leg to final to see how well you recognize a bum approach. Caution: Subjective opinions included.
INSTRUCTIONS: Answer the questions as best you can, then click on the "Score my quiz answers" button to see your score and read the explanations. If you don't like your score the first time around, you can change some of your answers and resubmit. To get the most out of this quiz, we suggest you keep trying until you get a perfect score.
NOTE: When more than one answer is true, only the most complete, correct answer will be scored as correct. The answers are assumed to apply within the United States unless otherwise noted.
Section=Postintro
Interactive Quiz #117
Why Make Bad Landings?
Section=Questions
1. Ask any flight instructor for an example of PFmax (maximum pucker factor) and you'll probably hear about some client (not necessarily a student pilot) getting low and slow on final. The hapless pilot tries to increase altitude by increasing pitch. That works for a second, sort of. But as lift momentarily increases, drag -- its sneaky cousin -- also increases. The pilot then attempts to clear the trees with more power and increased pitch. Sadly, as the FAA's Airplane Flying Handbook warns, "there comes a point where the angle of attack is so great and creating so much drag that the maximum available power is insufficient to overcome it." This causes pilot-induced pucker factor (PIPF) while operating in the region of (_____) or what's also called operating on the back side of the power curve. Please fill in the blank.
a. Reversed command
b. Inversed response
c. Adiabatic lapse
d. Coriolis response
e. Informed consent
2. You're in a Cessna 172. It's hot outside. All four seats are occupied, and you've turned final with power at idle and full flaps (30 degrees). You realize you're sinking too quickly. Luckily, you answered the previous question correctly and recognize the impending dangers, so you elect to go around. Your first step should be to:
a. Increase pitch to Vx
b. Increase pitch to Vy
c. Decrease flaps (initially retract to 20 degrees)
d. Increase power
3. Chances are wherever you land in this quiz there will be a crosswind. So, imagine you're on short final, flaps set, engine at or near idle, on glide path, stabilized with speed nailed ... in short, looking and feeling cool. But you're not done yet. The objective is to touch down without ripping the gear legs off while everyone's watching. The wind is from the right, so you're holding some right aileron and some (_____) rudder in order to touch down with the airplane's (_____) axis parallel to the runway. (No Ercoupes allowed.) Please fill in the two blanks.
a. Right, longitudinal
b. Left, lateral
c. Left, longitudinal
d. Neutral, vertical
4. Still working that crosswind from the previous question while landing in a Cessna 172: In order to assure that you continue tracking straight down the runway after touchdown, you should (_____) aileron deflection as your speed decreases.
a. Neutralize
b. Decrease
c. Increase
d. Reverse
5. One from our legal scholars who aren't really lawyers: FAR 91.135 (i) prohibits a not-for-hire pilot from operating a single-engine airplane (certified under FAR 23.45 as amended May 3, 1962) to a runway for the purpose of takeoff or landing when the wind (as reported by ATC, ATIS, ASOS or AWOS-3) exceeds the airplane's demonstrated crosswind component.
a. True
b. False
6. Flaps can be used to: (Select the most complete answer)
a. Produce greater lift and permit lower landing speed.
b. Produce greater drag, permitting a steep descent angle without airspeed increase.
c. Reduce landing roll distance.
d. All of the above.
e. Answers a and c.
7. Adding flaps on approach usually affects pitch. Normally, in order to maintain a stabilized approach while using full flaps the airplane's pitch attitude will be (_____) than the same airplane's pitch in a no-flap approach.
a. Higher
b. Lower
c. About the same
d. Could you repeat the question? I haven't finished my pre-landing checklist yet.
8. You don't need a seaplane rating to practice hydroplaning. You should, however, know that there are three basic types of hydroplaning. Which type occurs "during heavy braking that results in a prolonged locked-wheel skid?"
a. Dynamic hydroplaning
b. Viscous hydroplaning
c. Burnt-rubber hydroplaning
d. Reverted-rubber hydroplaning
9. Judge the veracity of this entire statement: Because the center of gravity (CG) is located forward of the main landing gear (normally) in tricycle-geared airplanes, they are immune to ground looping, the bane of tailwheel pilots.
a. True
b. False
10. Time now for Fun With A Porpoise. No, not Flipper's homage to Highlights magazine. Instead, we drop you into a Cherokee 180's PIC seat. You're cleared to land and, for test porpoises only, you are about to commit one of the most common (and preventable) landings errors: It's the bounce compounded by improper recovery. That oscillating up/down bouncing -- like a dolphin -- is called a porpoise. Air traffic controllers witness this on a depressingly regular basis and know that the average single-engine, tricycle-geared airplane will crash, break its nose wheel and slide like a belly-flopped sea mammal down the runway if a go-around is not initiated before the nose wheel impacts the runway for the (_____) time.
a. First
b. Second
c. Third
d. Fourth
Section=Answers
1. a
a. Yes! Reversed command is the ugly side of reality, flying up pucker alley ... a place you don't want to be. OK, we made up the PIPF part, but the rest is real. (FAA-H-8083-3A Ch 8)
b. No, that isn't it. Please select another answer.
c. No, that isn't it. Please select another answer.
d. No, you might be thinking of Coriolis force, a deflective force resulting from earth's rotation, which causes Oklahoma drivers to swing right before turning left. Please select another answer.
e. No. Please choose another answer.
2. d
a. No, that isn't right. Please select another answer.
b. No, that isn't right. Please select another answer.
c. No. Don't you dare touch those flaps yet! Please fly the airplane select another answer, quickly, the ground's coming up.
d. Yes! Not just increase but also smoothly add max power. Power may corrupt politicians, but in aviation power can get you out of trouble (depending on the situation, of course). Your POH should have a procedure for go-around/rejected landing, and power is probably at the top. Think: "Power, Attitude, Configuration." Flaps are usually brought up in increments to avoid sudden loss of lift.
3. c
a. No, that isn't right. Please select another answer.
b. No, that isn't right. Please select another answer.
c. Yes: left and longitudinal.
d. No, that isn't right. Please select another answer.
4. c
a. No, that isn't it. Please select another answer.
b. No, that's not right. Please try another answer.
c. Yes: Increase aileron deflection into the wind. Still hold the proper amount of rudder to steer the nose straight, but roll that yoke into the wind. Do not take your hands off that yoke to pat yourself on the back until the airplane is safely at the ramp with engine shut down and the control lock installed.
d. No, that's not right. Please try another answer
5. b
a. No, that isn't right. Please select another answer.
b. Yes, it's false. Not much in that statement holds true. The date May 3, 1962 is important because airplanes certified after that date come with a demonstrated crosswind component. This means that, under normal conditions, the average pilot should be able to handle that airplane with a 90-degree crosswind up to a velocity of 0.2 Vso or 0.2 of stalling speed in landing configuration at max. landing weight. If you, possessing well-above-average pilot skills, think you can wrestle winds stronger than that, then, have at it. Just don't be surprised when you run of rudder and have to demonstrate your exceptional go-around technique.
6. d
a. No, that isn't right. Please try another answer.
b. No, that isn't right. Please try another answer.
c. No, that's not it. Please choose another answer.
d. Yes. Flaps produce greater lift and permit lower landing speed, produce greater drag permitting a steep descent angle without airspeed increase and reduce landing roll distance.
e. No, that isn't right. Please try another answer.
7. b
a. No, that isn't right. Please select another answer.
b. Yes, it's lower. Here's the explanation from the FAA's Airplane Flying Handbook 8083-3A: "The pitch attitude of the airplane in a full-flap approach is considerably lower than in a no-flap approach." That's swell, but how does that affect the flare or roundout? Well, if you already have a lower pitch attitude because you've deployed all 40 degrees of your massive Cessna flaps (30 degrees in newer, wimpier Cessnas), then you'll need a bigger pitch change in the flare. Or as the Airplane Flying Handbook continues: "To attain the proper landing attitude before touching down, the nose must travel through a greater pitch change when flaps are fully extended. Since the roundout is usually started at approximately the same height above the ground regardless of the degree of flaps used, the pitch attitude must be increased at a faster rate when full flaps are used; however, the roundout should still be executed at a rate proportionate to the airplane's downward motion." Flaps: Use 'em if ya got 'em, but know what you're using or you could be surprised, particularly on a go-around in an older Cessna 150 at gross when you push in the throttle and all that happens is the cockpit gets noisier.
c. No, that's not it. Please choose another answer.
d. No, we can't repeat it. But feel free to reread the question and try another answer.
8. d
a. No, that isn't right. Please select another answer.
b. No, that isn't right. Please select another answer.
c. No, that's not it. Please choose another answer.
d. Yes, it's reverted-rubber hydroplaning. You're not burning rubber so much as steaming it. Here's what the Airplane Flying Handbook (FAA 8083-3A, Chap. 8) says happens when the airplane's rubber doesn't hit the road due to water: "Reverted rubber (steam) hydroplaning occurs during heavy braking that results in a prolonged locked-wheel skid. Only a thin film of water on the runway is required to facilitate this type of hydroplaning.
The tire skidding generates enough heat to cause the rubber in contact with the runway to revert to its original, uncured state. The reverted rubber acts as a seal between the tire and the runway, and delays water exit from the tire footprint area. The water heats and is converted to steam, which supports the tire off the runway.
Reverted-rubber hydroplaning frequently follows an encounter with dynamic hydroplaning, during which time the pilot may have the brakes locked in an attempt to slow the airplane. Eventually the airplane slows enough to where the tires make contact with the runway surface and the airplane begins to skid." Is there a cure? Sure: "The remedy for this type of hydroplane is for the pilot to release the brakes and allow the wheels to spin up and apply moderate braking. Reverted-rubber hydroplaning is insidious in that the pilot may not know when it begins, and it can persist to very slow groundspeeds (20 knots or less)."
9. b
a. No, that isn't right. Please select another answer.
b. Yes, it's false. Why? While the center of gravity (CG) is located forward of the main landing gear (normally), tricycle-geared airplanes are in no way immune to ground looping, which is, indeed, the bane of tailwheel pilots who get lazy on landing and forget why the FAA issued pilots feet.
10. c
a. No, that isn't right. Please select another answer.
b. No, that's not right. Please try another answer.
c. Yes, three bounces. This is based on extensive scientific studies performed by the Brainteaser author during his too many years as an FAA air traffic controller (tower). Conclusion: 1) The control tower is a great place to watch bad landings, and 2) Pilots who insist upon landing nose-wheel first will bounce. Boing!
A tiny first bounce can be salvaged with proper pitch and, perhaps a spritz of power. But, should the poorly-trimmed, nose-heavy airplane smack nose-first a second time -- Bwa-Boing! -- the resultant bounce will be higher with staggering consequences. If left uncorrected -- by now the only out is a go-around -- the abused airplane will absolutely, no-doubt-about-it, smack the runway a third and final time. At this point the nose strut, plus all its delicate and expensive parts, will shatter, bend, and generally explode, leaving the PIC, who's not really in command, wondering, "Wha-happened?"
Remember: There are only two landing-gear wheels in a tricycle-geared airplane -- the left and right mains. The nose wheel is there to keep the propeller off the pavement; it's not for landing. One more reason to fly tail-draggers.
d. No, that's not right. Please try another answer.
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