|
Getting your Trinity Audio player ready...
|
There’s a concept called ‘tolerance stack-up’, an example of which can be found in engine building. Wherever moving surfaces meet, a supply of oil is essential to minimize wear and restrain heat buildup. When assembling an engine, care must be taken to measure and record the gaps (tolerances) between each of these moving surfaces. An extra thousandth of an inch might seem negligible. But, if an engine has excess tolerance in each of a dozen or more bearings, the result is extra gap between those surfaces that oil must fill. An engine oil pump will produce flow that increases as engine RPM increases up to a point beyond which further increase of RPM will not produce more flow. If the tolerance stack-up is too great, oil pressure will not build, and the loose engine will experience higher temperatures and an increase in wear.
Mistakes that we make in all phases of flight can “stack-up” too, and the result can be fatal. The decision to write this was a difficult one. Because I’m a low time private pilot, (425 hours, high performance and complex endorsements) I am not in a position to offer advice to anyone. I consider my ticket to be an earned opportunity to learn. But perhaps another beginner pilot will take something useful from my experience, so my pride notwithstanding, here is what happened.
I had a planned flight with a passenger scheduled the following Monday, and as it had been a while since I had flown a light, high wing airplane, I figured a refresher would be a good idea. It was a usual Midwest summer Saturday. Nothing in the METAR or TAF for the Spirit of St. Louis Airport, KSUS (hint – mistake 1) provided any reason for concern about my planned local flight.
I scheduled the last remaining aircraft – the lone and very used 172R model in the fleet. (hint – mistake 2). I had flown that aircraft in the past and recalled thinking that there would not be a second date. (hint – mistake 3).
The preflight was normal. I set up my Stratus and Foreflight, requested a departure heading, and was soon airborne and headed out of the Class D airspace and toward Washington Regional Airport, KFYG, which is where students from our flight school typically carved up the pattern and learned just how much spring there was in the Skyhawk landing gear.
I sequenced into the pattern and made three decent landings. The pattern was too full of airplanes for my taste, and I announced a downwind departure. As I climbed out and to the south, I thought I noticed a change in the winds. I tuned in the ATIS frequency for KSUS and was unpleasantly surprised to hear that the wind was now from 210 degrees and gusting to 17 knots. I calculated that I would have a left crosswind between six and 13 knots. I called tower and reported inbound. I asked about the wind and was advised that the METAR was 2108G17KT, but he was seeing wind variable from 180 to 210 degrees. I continued inbound for runway 26R. (hint – mistake 4).
With the wind gusting to 17 kts., I calculated a left crosswind between of 6-13 kts.
26R is right traffic, but tower gave me a left downwind for traffic and he would call my turn. As I flew along, I was certain he had forgotten me, so I made a call whereupon he immediately called my turn and cleared me to land. I adjusted my thinking for a straight in approach. I had learned to fly using 26R and I knew the pattern, the landmarks that worked for me, and the sight picture. I picked out the U-shaped building that I always used to initiate my base turn and determined that I would cross that at 70 knots. The ride was smooth and gust free. I crossed the landmark building at 70 kts. and had two red and two white on the PAPI. My approach was stable. (hint – mistake 5). It bears noting that there is a 400′ bluff just south of the field at KSUS. When winds are from the south, that bluff becomes a salient factor for pilots.
I always read the accident briefs published by Plane and Pilot Magazine. In each, I try to find a lesson that one day might save my life. It never occurred to me that I would be the subject of one of those accident briefs.
Probable Cause and Findings
The National Transportation Safety Board determines the probable cause(s) of this accident to be:
The pilot’s failure to maintain control of the airplane while landing in gusting wind conditions, which resulted in a hard, bounced landing and the nose landing gear collapsing.
The Stack -Up
Mistake 1.
My cursory review of the METAR and TAF should have been augmented by a review of the various other resources available. What does the TAF indicate at other airports in the direction from which the wind was emanating? An app called Windy also provides some very useful data for both present and forecast winds. Foreflight has useful wind depiction features if you have the required subscription. Winds on any summer day in the Midwest can change abruptly and often.
Mistake 2
Most of my 172 experience has been in the S model. The airplane I scheduled that day was an R model. I never took the time to study the POH for the R model as I had the S model and for every other airplane I have flown. I just assumed – you know, it’s a Skyhawk. 20 fewer horsepower, different stall speeds, different white arc, different RPM range. Singly, those minor differences are probably not enough to give a pilot trouble. But all stacked up and in a moment of emergency, they can cause chaos.
Mistake 3
I had flown that airplane before and decided that I didn’t want to fly it again. I should have taken some time to think through the reasons why I walked away from my first encounter with a negative impression. I had apparently become complacent to the point of ignoring my own assessment of the aircraft.
Mistake 4
Given what the controller in the tower had told me about wind variability, I should have recalculated the potential crosswind. The METAR values indicated a crosswind component of 13 kts. from the left. The extreme of the variability of 180 degrees rather than 210 degrees, pushed that number to 17 knots. 17 kts. of gusty crosswind in a 172 is approaching the limits of my personal comfort level. But the air was smooth and gust free. (In fact, the NTSB report states that the wind was 19011G17KT at the time of the accident.)
Mistake 5
We all were taught to add half of the gust factor to final approach speed. The gust factor would have been about 9 kts., so I should have carried an extra five kts. on final. But, I reasoned, I was experiencing no gusts, everything looked and felt right, I had the glidepath and was right on my planned speed.
The data shows I was 30 feet above the runway with a ground speed of 58 knots. I had 20 degrees of flaps. Power had just been set to idle. The airplane suddenly was blown to the right of centerline by a strong gust. I immediately put in left aileron and worked the rudder to get back to centerline. Just as abruptly the gust was gone, and I felt a sensation that I had not felt before in an aircraft. The left wing simply stopped flying – as if there was no lift at all. This did not develop like any stall I had ever experienced. It was not progressive, but rather sharp and sudden. The left main contacted the runway which induced a significant bounce and propelled the aircraft to the right. I always have my hand on the throttle during landings and my first instinct was to go around. Just then the right main made contact and induced a second bounce. I made the decision in that split second that adding power to what was now an out-of-control scenario would be a bad decision. I worked the control surfaces and brakes as best I could and aimed for the grass. The second bounce led to a flat landing, the nose gear collapsed, the prop hit the runway, and you can guess the rest. At some point I had pulled the fuel cutoff, killed the mags and master, and opened the door.
All my mistakes that day stacked up and, in the end, my skill as a pilot was not sufficient to overcome them. I had forgotten that gusts reported on the ground coupled with smooth air just above meant that I should expect wind shear. I didn’t consider that 400′ bluff just south of the field. Gusting surface winds from the south drop off that bluff and cause all manner of havoc. On that day, during that landing, that havoc came in the form of low-level vertical wind shear.
Would the extra 5 kts. of speed on final have changed the outcome of that landing? Maybe. Should I have executed a go-around? Affirmative.
The sounds that filled the silence after the engine quit will stay with me forever. An airframe does not bend silently; the fuselage does not slide on asphalt quietly; and the violence of that landing will forever be a part of this Airman’s psyche.
I should have executed a go-around.
- Multiple mistakes were too much to overcome - May 3, 2023
- Learning to fly the wrong way—and loving every minute of it - January 22, 2020
Thanks for sharing! Wondering what the aftermath was with the plane (repaired or replaced?) and how the flying club reacted. Most importantly though – you are safe and sharing your experience might prevent a fellow pilot from a similar fate.
This plane is still being used for instruction. https://flightaware.com/live/flight/N24783
They bought it back, sent it off to be Frankensteined back to life. No. Thanks.
Which is it; a private pilot with 425 hours, a high performance and complex endorsement; OR a STUDENT PILOT with more than 250 hours in mostly the wrong airplanes? It can’t be both!
Good catch. My bio is out of date.
There is a line from the famous classic western film “The Good, The Bad, and The Ugly.” A bad guy bursts in on one of the main characters, who was taking a rare in those days bubble bath, presumably to kill him. The bad guy stands with gun pointed at our bather calling him out and jabbering away, at which time our bather raises a six gun from the suds and abruptly pulls the trigger! “IF YOU’RE GOING TO SHOOT, SHOOT! DON’t TALK.”
If your going to go around, DON’T THINK, JUST DO IT, GO AROUND.
Under difficult crosswind conditions, time can be your friend. On the next approach, you will know what to expect, what was and was not working the first time, have time to calm yourself and reassess if this runway, or indeed this airport!, is the best option for a safe landing. In 40+ years of flying, I’ve changed airports for a more suitable x-wind runway more than once. Sometimes all the preflight planning won’t help you when the weather is not what was forecast, but a go around will.
Glad you’re safe.
Exactly one the lessons I took from the experience.
Thanks for sharing Jim! I fly often out of KSUS, my home airport and it was interesting to learn about your experiences. Lots of rotorcraft activity at KSUS also that can cause some unexpected experiences.
Rotorcraft… taking off on 8L and a helo student taking off drifts right right into my flight path as I was climbing out. Tower was great but I still had to aggressively maneuver way to close to terra firma.
1. First sign of trouble regarding the establishment of an approach or landing, go around, https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/04_phak_ch2.pdf
2. Because someone has x amount of hours does not make them impervious to making mistakes. I read a lot of NTSB reports, so many true catastrophes or high hour pilots, one famous incident in a GA aircraft, a well known test pilot. However, regardless of your ‘hours’, the frequency which should have a direct impact on your proficiency, is most important once a pilot is ‘signed off’ on his or her own.
It is our responsibility to continue training and practicing. As a recent student I can say with great assurance that current CFIs generally shy away from xwind training and IMC training. They are barely 250 plus pilots themselves and with constant ‘threat’ of the new ‘make money hand over fist’ flight school model, discouraged from taking any risks above the minimums to get a student through the meat grinder.
All this to say, if the winds don’t look good, if the plane don’t look good, if the gauges, approach, anything don’t look good, save the NTSB a trip and call it.
As for the story, seems like the pilot did the best he or she could with the experience in that specific configuration and weather circumstances they could, it’s not up to us to Monday morning quarter back a legitimate accident.
Thanks. The thing was that I was right on speed, on glide path, aligned with centerline, and configured correctly for the circumstances. And then BAM!!! Low level vertical wind sheer. The left wing didn’t stall in any way that I had ever experienced. The critical angle of attack was not a factor. I’m still trying to fully understand the physics of what happened. But yes, mash the throttle and get the hell out of there.
I can relate to this story, but mine did not end in damage. I was coming in to land with crosswinds at 12 knots after what had been a pretty bumpy ride in the area. I was lined up well on final and just counting down to landing when at about 50 feet from the runway a sudden gust pushed me horizontally. I was now over grass. I immediately pushed in power and executed a climb. On the way up, I decided that I would try one more time, and if it was not a success on the second attempt, I was going to the nearby towered airport that had longer, wider runways with better alignment with the winds that day. On final, it was bumpy, but I did not have a repeat of the gusts to that magnitude, and I landed smoothly that time. I parked the plane, and I was so happy to walk away from it. I learned to pay more attention to winds aloft, knowing that they change somewhere in the air, but we don’t know where. Wind shear is a scary thing.
250 hours and still no PPL? I’d love to know why. That bit of data seems to suggest that the author has not learned or for some combination of reasons is unable to learn the basic skill set needed to successfully pass a check ride, and possibly should consider ending this hobby before he injures himself or others.
Good comment. I lease airplanes for business. (C310 and C421). Pilots we use are retired ATC or retired airlines. So, I was a student pilot and flying for business and they ask “you want to fly?” Um, well, hell yes. The fact is that I learned to fly with these amazing older guys in piston twins. My only other article I’ve published here details all of that. Was it legal? In fact yes it was. Would i recommend it? The circumstances are so edge case that the question is not relevant. What would you have done?
I learned to fly in the 69’s by s WW II fighter pilot. He made me do things the FAA would not tolerate today. Whether it be right or wrong it was drilled into me in a 150 or 172 no flaps on cross wind landings period. I had similar experiences as said above and always had plenty of air speed to either get straightened out or a go around which I opted for both when necessary. In SD a lot of wind always. We routinely in 172’s did 45 degree 30 mph and 90 degree 20 mph. As an airport bum at the time in winds at 45 mph with a 15 to 20 degree an experienced pilot we knew was going to land a Piper Super Cub. We knew once the tail was down with a positive lift angle he could flip. 4 of us ran midway down the strip on each side trying to determine touch down spot with his slow ground speed. We were accurate enough that when he chopped power we were able to grab the wing struts and walked him to his hanger. He elected fuel up later no need for the wind to blow him into a gas pump or something else.
Decades ago on a business trip to the Eastern Shore, I rented a Warrior at a small rural airport. As I completed the checkride, and was on final, I discovered a 90 degree, extremely gusty, x-wind for runway 36 (single runway). I went half-flaps, and kept the speed up… didn’t want one of those gusts to quit on me, and the wings having nothing to work with. I dunno the wind speed, but to line up with the runway, I had to crab 20-25 degrees (or maybe more) into the wind coming from starboard. Touchdown was gonna be ugly, so at 15-20 feet, I put in considerable right aileron and left rudder hoping to get stabilized before the crash. Concerned about the right wingtip, but the airport gods (or maybe the real God) was with me, and I knew the right main was down only by the rumble. But then the wind quit for a moment, and the left main dropped… but, at least it was rolling straight down the runway rather than sliding sideways, or tearing the gear off. I had to be near, or maybe past the crosswind component limit for that plane, but the only thing the check-pilot said as we taxied in was “Nice,”. I appreciated the compliment, and was glad I didn’t experience the identical circumstances described in this article.
Sometimes ya win, and sometimes ya learn… it’s nice to win AND learn.
Curious what the magnetic declination is. Article reads as if the taf and metar are magnetic north. Maybe that’s a difference with Canada but up here they are both reported as true north.
I guess there’s nothing that makes a pilot feel worse than seeing a broken airplane sitting awkwardly in a place it shouldn’t be all because of something he did or did not do. You have learned from your mistakes (just like we all should learn from our own…), and you’ll never make them again. So, don’t let it get you down; you’ll be a better pilot going forward from here. And, by the way, anyone out there who says he’s never experienced one of these “embarrassing moments” has simply never pushed himself beyond what he already knows and feels comfortable with. If your mind and skills are not being tested and challenged, you’re really not growing and learning. And in aviation, learning sometimes produces copious amounts of carbon dioxide and adrenaline. I can assuredly tell you this after successfully demonstrating three times in a row that a long-bodied airplane with a large rudder can effectively handle a documented fifty-knot direct crosswind while landing. Keep flying and learning.
Thank you. And thank you again.