Tag Archives: accident

Dangerous Flying: Abrupt Control Inputs

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How sloppy flying could get you killed.

Recently, while flying with a 200-hour helicopter pilot, I was startled when he rather abruptly shifted the cyclic to make a turn. I didn’t say anything then because it wasn’t too abrupt (whatever that means). But when he did it again later in the flight with an even more abrupt movement, I spoke up and told him not to do it again.

Understand that we were flying a Robinson R44 Raven II, which has a rather unforgiving semi-rigid rotor system and very long rotor blades. We’re taught — or should be taught — during primary training to use smooth control inputs, especially when working with the cyclic.

I’m not a CFI and I don’t feel that I have the right to tell someone how to fly, but when a pilot does something I believe is dangerous, it’s my duty to speak up. So I did.

The trouble is, I’m not sure if he believes what I told him — that abrupt inputs are dangerous — or if he thinks I was just nitpicking his technique. (I let it go the first time partially because I didn’t want to be seen as a nitpicker.) Since so many pilots seem to read this blog to learn — or at least to get my opinions on things — I thought I’d discuss it here.

What Robinson Says

Section 10 of the R44 II Pilot’s Operating Handbook includes safety tips. Here’s the one that applies:

Avoid abrupt control inputs or accelerated maneuvers, particularly at high speed. These produce high fatigue loads in the dynamic components and could cause a premature and catastrophic failure of a critical component.

What Robinson is saying is that when you make abrupt control inputs you put stress on various aircraft components. They’re likely concerned about the rotor blades, mast, transmission, and control linkages most. This makes perfect sense.

Robinson Safety Notice SN-20, titled “Beware of Demonstration or Initial Training Flights,” includes these statements:

If a student begins to lose control of the aircraft, an experienced fight instructor can easily regain control provided the student does not make any large or abrupt control movements. If, however, the student becomes momentarily confused and makes a sudden large control input in the wrong direction, even the most experienced instructor may not be able to recover control.

And:

Before allowing someone to touch the controls of the aircraft, they must be thoroughly indoctrinated concerning the extreme sensitivity of the controls in a light helicopter. They must be firmly instructed to never make a large or sudden movement with the controls.

Of course, what worries Robinson here is that student pilots may make erroneous control inputs beyond what an instructor can fix to regain control of the aircraft.

What Worries Me More

January 31, 2012 note: Since writing this, a friend on the Rotorspace site has brought the topic of Mast Rocking to my attention. Apparently, some folks think that this accident may have been caused by Mast Rocking rather than an abrupt cyclic control input. I’m not convinced. Mast rocking supposedly does not cause the main rotor blades to diverge from their normal plane of rotation. How else could the tail be cut off in flight?

But what worries me more than putting stress on components is an accident report from 2006. I read this report on the NTSB Web site not long after the accident occurred. Back then, there was no known reason why an R44 helicopter with just two people on board for a long cross-country flight should fall out of the sky with its tail chopped off, but I had my suspicions. After my recent flight with the new pilot, I looked it up again. Here’s the probable cause (emphasis added):

The Canadian certificated commercial helicopter pilot was conducting a cross-country delivery flight with a non-rated passenger occupying the copilot seat. The passenger and pilot together had previously made delivery flights from the Robinson factory to Canada. Two witnesses saw the helicopter just before it impacted the ground and reported that the tail boom had separated from the fuselage. No witnesses were identified who saw the initial breakup sequence. Both main rotor blades were bent downward at significant angles, with one blade having penetrated the cabin on the right side with a downward slicing front to rear arc. The primary wreckage debris field was approximately 500 feet long on an easterly heading. The helicopter sustained damage consistent with a high-energy, fuselage level, vertical ground impact. Detailed post accident investigation of the engine, the airframe, and the control systems disclosed no evidence of any preimpact anomalies. The removable cyclic was installed on the left side copilot’s position, contrary to manufacturer’s recommendations when a non-rated passenger is seated in the left seat. The removable pedals and collective for the left side were not installed. The cyclic controls for both the pilot’s and copilot’s positions were broken from their respective mounting points. The copilot’s cyclic grip exhibited inward crushing. The Safety Board adopted a Special Investigation Report on April 2, 1996, following the investigation into R22 and R44 accidents involving loss of main rotor control and divergence of the main rotor disk, which included a finding that the cause of the loss of main rotor control in many of the accidents “most likely stems from a large, abrupt pilot control input to a helicopter that is highly responsive to cyclic control inputs.”

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
a loss of control and the divergence of the main rotor blade system from its normal rotational path for undetermined reasons.

(A full narrative is also available.)

This is pretty much what I’d imagined. The helicopter is cruising along at 110 knots in a very boring part of the California desert. For some reason, the pilot (or his passenger, who has access to a cyclic control), jerks the cyclic one way or the other. Maybe he was trying to dodge a bird. Maybe he was goofing off or pretending to be Airwolf. Who knows? The sudden input is enough to cause the blades to diverge from their normal path. One (or both) of them dip down and chop off the tail boom. The result: two dead bodies in a 500-foot long debris field.

And this is what was going on in the back of my mind when the pilot beside me made those sudden inputs.

Anyone who has flown a Robinson helicopter can tell you how responsive the cyclic control is. It wouldn’t take much effort to knock the blades out of their path. That’s why we’re taught — or should be taught — to use smooth control inputs.

Other accident reports like this one include: CHI05CA267 and MIA00FA102 (which is a “watch this” moment).

Other Concerns

Rotorcraft Flying HandbookThere are at least two other reasons to avoid abrupt cyclic movements. You can find all these in the Rotorcraft Flying Handbook, an FAA publication that’s a must-have in any helicopter pilot’s library.

Under the “Retreating Blade Stall” heading (page 11-6):

High weight, low rotor r.p.m., high density altitude, turbulence and/or steep, abrupt turns are all conducive to retreating blade stall at high forward airspeeds.

Personally, I don’t think retreating blade stall is an issue in Robinson helicopters, except, perhaps, at high density altitudes and high speeds. But in that case, you’d be exceeding Vne.

Under the “Low G Conditions and Mast Bumping” heading (page 11-10):

For cyclic control, small helicopters depend primarily on tilting the main rotor thrust vector to produce control moments about the aircraft center of gravity (CG), causing the helicopter to roll or pitch in thedesired direction. Pushing the cyclic control forward abruptly from either straight-and-level flight or after a climb can put the helicopter into a low G (weightless) flight condition. In forward flight, when a push-over is performed, the angle of attack and thrust of the rotor is reduced, causing a low G or weightless flight condition.

You can find an account of this (with a lucky pilot and passenger) in this accident report from July 22, 2010. Indeed, the problem may have occurred during the right turn the pilot initiated — did he jerk the cyclic over as my companion had done?

Another accident report that suggests mast bumping is SEA03FA148 (which took the life of a pilot I knew).

I’m Not Just Nitpicking

The point of all this is that I’m really not just nitpicking a fellow pilot with limited flight time. He performed a maneuver which I consider dangerous and I have all this information to back me up. It’s important for him — and for others who might not know any better — to avoid abrupt control inputs.

Robinson helicopters aren’t capable of safely performing aerobatic maneuvers. Don’t fly them as if they are.

Update, March 17, 2012: Here’s another example of an accident likely caused by an abrupt control input. This one resulted in mast bumping.

Interesting Links, May 5, 2011

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Here are links I found interesting on May 5, 2011:

Pilot Flying Fears?

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Education is the best way to deal with safety concerns — especially if you’re a pilot.

I recently took part in a forum discussion that revolved around safety issues. The person who started the discussion, a helicopter pilot training to be a CFI, was concerned about the possibility of flight schools emphasizing the fun part of flying without adequately addressing the dangers. It wasn’t a failure to teach emergency procedures that bothered him. It was the attitude of flight schools and CFIs. He worried that flight schools, in an attempt to keep enrollment high, were failing to make students understand just how dangerous flying helicopters can be.

While I’ll agree that flying helicopters is dangerous, I also agree that driving a car or or crossing the street is dangerous. In fact, you stand a far more likely chance of being injured or killed in a motor vehicle than in an aircraft. The pilot who started this discussion knows this, but he still wonders whether flight schools should be making student pilots more cognizant of the dangers, especially early on in training.

I understood his point of view, but I really don’t know firsthand how much his flight school is downplaying the dangers. The general feeling I came away from after reading his comments was that he had a fear of flying. (This turned out not to be the case.) While it’s always good for a pilot to be afraid of what could happen, there comes a point where the level of fear becomes unhealthy. Yes, it’s true that pilots need to be mentally prepared to react to an emergency within seconds. But no, we don’t need to spend every moment of every flight actively thinking about all the emergencies that could ruin our day — or end our life.

Experiences Teach

I flew with a 300-hour pilot a few years ago. He’d gone through training and was a CFI looking for a job. (I have flown with quite a few CFIs looking for jobs, but that’s another story.) We were on a cross-country, time-building flight in my R44. I would eventually fly a total of 20 hours with him.

Early on in our first flight, I learned that his CFI, who was the flight school’s Chief Flight Instructor, had been killed in a rather disturbing fiery crash. Although she had over 2,000 hours of flight time, she had only 24 hours in the helicopter make and model. On that fateful day, the NTSB concluded that the accident was caused by:

The pilot’s improper planning/decision in attempting a downwind takeoff under high density altitude conditions that resulted in a loss of control and impact with terrain. Contributing to the accident were the helicopter’s gross weight in excess of the maximum hover out of ground effect limit, a high density altitude, and the gusty tailwind.

(I don’t really want to discuss this accident here; I think deserves a discussion of its own elsewhere in this blog and hope to address it in the months to come.)

Near GormanIt soon became apparent to me that the pilot was unusually fearful of flying in the mountains. Our route required us to fly west from Wickenburg, AZ to the California coast near San Luis Obispo. He started fretting about the mountains ahead of us while we were still in the flat deserts of Southern California. The mountains he was worried about showed elevations of 5,000 to 8,000 feet on the chart; we’d be flying over a road that ran in a relatively straight and wide canyon. That part of the flight turned out to be uneventful and he seemed genuinely relieved when it was finished.

Monterey BayOddly, later in the flight, when the Monterey tower instructed us to cut across Monterey Bay at an altitude of only 700 feet, I was pretty freaked out. Here we were, in a single-engine helicopter flying far from gliding distance of land, without pop-out floats or personal floatation devices. My companion, on the other hand, was perfectly at ease. In fact, I think he thought me cowardly when I asked Monterey tower for clearance to fly closer to shore.

This is a great example of how experience teaches. My companion was a “sea level pilot,” who did all of his training — and flying — in the watery areas around Seattle. He was comfortable with water and low-lying lands, but he was fearful of the conditions that had taken the life of someone he knew very well. I was a desert pilot with most of my experience flying over dry land, much it in high density altitude situations, including more than 350 hours flying tours over the Grand Canyon at 7500 feet or higher. I was comfortable flying over most kinds of terrain at just about any altitude but very fearful of flying over water.

(Nowadays, I wear a PFD when doing any extended flying over water and require my passengers to do the same.)

Learn from Other People’s Mistakes

Back in the forum, I began wondering if the pilot who had started the thread was concerned because he’d lost someone close to him in a crash — much like my cross-country companion had. (That turned out not to be the case.) I said:

If a person thinks too much about the danger of ANYTHING, they won’t be comfortable doing it. I admit that I don’t concern myself with it. I do everything I can to fly safely and maintain a safe aircraft. I’m confident in my abilities and never push the envelope of comfort more than I absolutely need to. I don’t fly around thinking that at any moment, something bad could happen. If I did, I’d hate flying and I’d likely be a horrible pilot.

Later, in the same post, I said:

You might also consider reading NTSB reports for helicopter accidents. What you’ll find is that most accidents are caused by pilot errors. REALLY. Reading those reports will help you learn what mistakes others have made so you’ll avoid them in the future.

He saw these two comments as conflicting and replied that I couldn’t really say that I wasn’t concerned with danger if I was reading accident reports.

My response was:

You need to understand that it’s BECAUSE I read the NTSB reports that I’m NOT overly concerned with the dangers of flying. The NTSB reports educate me about what can happen when you do something dumb: fly too heavy for your type of operation, perform maneuvers beyond the capabilities of your aircraft, fly into clouds or wires, etc. Each time I read a report and understand the chain of events that caused the accident, I file that info into my head and know to avoid the same situation.

I went on to say a lot more about what I’ve learned from NTSB reports. I read them for helicopter accidents at least once a month. Another pilot in the forum said he does the same thing — in fact, he even has a browser bookmark that’ll pull up the reports by month! I cannot say enough about the usefulness of these accident reports for training and awareness.

Unanswered Questions Can Fuel Fear

As I look back now on the flights I took with that mountain-fearful CFI — with the forum discussion in mind — I’m wondering whether the flight school had properly debriefed its students after the loss of the Chief Flight Instructor.

What had the flight school told him and the other pilots? Had they told him what caused the crash? I know that back then, before the NTSB report was issued, the flight school was in denial about the aircraft being overweight for the operation. Had they told their students anything at all? Were my companion and the other pilots and student pilots at that flight school left to wonder how such a great, experienced pilot could have been involved in a crash in the mountains?

Were his unanswered questions fueling his fear?

Another thing I suggested in the forum is that flight schools might want to conduct monthly seminars that students are required to attend as part of ground school training. Get all the students and CFIs into a classroom or meeting room with a few knowledgable, experienced pilots at the front of the room. Pick 3 to 5 recent helicopter accidents for which the cause is known. Talk them out. Explain what went wrong and what could have prevented the accident. Don’t point fingers; present facts.

Why don’t flight schools do this? Could it be because of what this forum pilot originally said: flight schools don’t want to scare off students by discussing dangers? If so, they’re doing their students — and the rest of the aviation community — a serious disservice.

Education and Experience are the Answers

Nowadays, if you want a job as a pilot carrying passengers for hire, you’ll need at least 1,000 hours of experience as a pilot in command. (Yes, I know some companies will take less, but those are few and far between.) There’s a reason for this: they want pilots who have experience flying. Experience leads to skills, knowledge, and confidence.

Some people think 1,000 hours is an arbitrary number and frankly, I have to agree. My first 500 hours were very different from the average CFI‘s first 500 hours — in some respects, my experiences are “better,” while in other respects, a CFI‘s experiences are “better.” But I also can’t see any other easy way to gauge a job applicant’s level of experience.

But it isn’t just experience that makes a pilot a good pilot. It’s also knowledge and attitude. Both of these things could be the end product of a flight school’s training program.

Many flight schools seem satisfied getting students and putting them through a “program” with just enough skills and knowledge to pass a check ride. Many students, who don’t know any better, are more interested in the cheapest way to get their ratings than the quality of the training.

I believe that with better quality training and better quality experience, less hours of experience should be necessary to have and prove good piloting skills. I also believe that pilots with better quality training and experience will have a better, safer attitude toward their responsibilities as a pilot.

It’s not a matter of teaching new pilots to be fearful of what could happen by stressing the dangers of flying. It’s a matter of educating about dangers — and how to avoid them.

What do you think?

About the Cherry Drying Posts

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And why they’re password protected.

Drying CherriesA few weeks ago, it came to my attention that this blog was the primary source of information about cherry drying by helicopter. Every day, pilots who wanted to learn more about cherry drying were stopping in to read up.

Normally, I’d be pleased. But I also began to realize that these same pilots were using the information I provided to compete with me for cherry drying work.

That would simply not do.

The truth of the matter is, there simply isn’t enough work to go around. Every year, I struggle to get my contracts together and signed and then struggle some more to get my standby pay. Other pilots I know who have been doing this work far longer than I have go through the same process. None of us can afford to have competition for what little work is out there.

In my case, it’s particularly tough. I travel from Arizona to Washington and back at considerable cost. This year, I made the trip with only one contract signed. If I hadn’t been able to secure other work, I would have taken a heavy loss.

In this tough economy, I depend on this work to keep my business afloat. Without it, I’d likely have to sell the helicopter. Right now, there simply isn’t enough tour and charter work out there to cover the cost of my fixed expenses, such as insurance, annual maintenance, and hangaring.

So I’ve password-protected the posts, making them inaccessible to most visitors. I’ll likely remove the password once my friends and I stop doing this work.

Some Important Things to Know about Cherry Drying

I do need to say a few things about cherry drying for the folks looking for information.

  • Cherry drying requires a helicopter. If you don’t have a helicopter, you cannot dry cherries. Any company that has helicopters for this kind of work already has pilots. Inexperienced pilots cannot expect to be hired for this kind of work by a company that already has helicopters and pilots.
  • Cherry drying is not a good way to build time. I got less than 20 hours of drying time this summer. I got around 5 hours each of the previous two years. Do you really want to blow a whole summer sitting around in farm country waiting for it to rain just to get 5 to 20 hours of flight time?
  • Cherry drying is not for low-time pilots. When you work, you’re hovering 5 feet over treetops, sometimes in very windy conditions. That means tailwinds and crosswinds and LTE. There’s a lot of dancing on the pedals. There’s a real need to know the helicopter you’re flying.
  • Cherry drying is dangerous. All operations are inside the deadman’s curve. If you have an engine problem, you will crash. Read these accident reports to get a better idea of what can happen: SEA05CA122, SEA04LA102, LAX02LA169, SEA00LA101, SEA00LA103, WPR09LA371, and WPR11CA146

I know a lot of helicopter pilots — especially low-time helicopter pilots — out there are desperate for work. If you’re one of them, I can assure you that cherry drying isn’t the solution you’re looking for.

Two Close Calls

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One, another pilot’s; the other, mine.

I flew up to Chelan, WA to visit a friend on Wednesday. The weather here in central Washington State has been too good to force a cherry drying pilot to sit around and wait for rain. I’m sure my clients didn’t even miss me. (Heck, I could have been back in Quincy in 30 minutes if they needed me.)

I flew direct to Chelan, enjoying some low-flying over the wheat fields of the Waterville Plateau. I know where all the wires are up there and I wasn’t that low. But I do admit that I enjoy the rush of flying at 120 miles per hour 100-200 feet off the ground. The flat expanse of the Plateau is perfect for this kind of flying — you can cover the entire north-south distance without flying over a single home or business.

The descent down to Chelan is always a thrill. First I sometimes need to climb a bit to cross over the tops of four or six sets of high tension power lines that run east-west across the north end of the Plateau. Then I’m at the edge of the Plateau and the earth drops away to the Columbia River over a thousand feet below. My two-bladed rotor system makes it dangerous to do a nose-over dive like you might see in the movies. Instead, I have to content myself with lowering the collective almost to the floor and settling into a 1,000 to1,500 foot per minute descent rate. I always descend downriver from Chelan Airport, so I have to bank to the right and follow the river northeast. By the time I get to the airport, I’m only 100 feet above its field elevation, mostly because it sits on a shelf over the river.

I used to do this flight a lot more often when my finances were better and I could afford to fly on my own dime. Things are different now and I’ll likely make this trip only once or twice this whole season. This was my first time this year and I’ve been here nearly two months.

Three R44s Parked at ChelanMy friend met me at the airport. He’s a helicopter pilot too and he’s also in Washington to dry cherries. His helicopter is parked at an orchard. There were two other R44s parked in a field at the airport and I parked with them. But I didn’t bother shutting down. I invited my friend to join me for a flight further up the river to Brewster, where another friend of mine’s old Sikorsky S55T (and that T stands for “turbine”) is recovering from a mishap last season. We flew up the river, pointing out all the orchards we’d dried in the past along the way.

Close Call #1

Back at Chelan, I parked with the R44s again and shut down. The Airport Manager drove up with his dog in his pickup and chatted with us as I locked up. We could hear the sound of a helicopter running on the other side of an old hangar. The airport manager told us about the pilot, a man who had likely been flying helicopters since before I was born. As we chatted, we could hear the engine winding up as the pilot got the helicopter to full RPM. My friend started walking toward the hangar to get a better look at the pilot’s departure; he was out of sight from where we stood.

A sickly bang! sound rung out. It was not the kind of sound I’d ever want to hear anywhere near where my helicopter was spinning. An older helicopter came into view around the front of the hangar, flying erratically. The pilot got it under control easily and continued hover-taxiing to the fuel pumps about 100 feet away. As he set it down, my friend picked up a piece of something and started walking back to us with it.

It was a splintered piece of wood.

Meanwhile, three men in a hangar nearby came out onto the ramp. Together, we watched as the pilot shut down the engine. The blades slowed. They didn’t even come to a full stop before I saw the damage.

The outboard 6 to 8 inches of each of the two main rotor blades had been severed. My friend was holding a piece of one of them; the other one was on the ramp. The blades had struck a steel I-beam that extended out beyond the hangar walls. He’d probably hovered past that spot a thousand times in the past. This time, he cut it a bit too close.

I call this a close call because of what could have happened. The blades could have disintegrated as the pilot hovered. He could have lost control of the helicopter. We could have been dragging his injured or dead body out of the wreckage. Worse yet, the wreckage would likely have flown all over as the helicopter beat itself to death on the ground. My friend could have been struck with flying debris. Heck, I could have been struck, too. And I wasn’t even that close.

Needless to say, the pilot was very angry with himself. We all felt bad for him, but there was nothing else to do but wheel the helicopter back into its hangar until repairs could be made.

Close Call #2

I had a nice day in Chelan with my friend. We had lunch at a downtown cafe where we could sit outside in the shade. Then we went to Blueberry Hills and had some pie. (I had to skip dinner to keep my calorie count down for the day, but it was worth it. I love rhubarb pie.) Finally, at about 6, my friend drove me back up to the airport. We said our goodbyes, I climbed aboard Zero-Mike-Lima, and started up.

A small private jet made a magnificent departure from the short runway just before I was ready to take off. He climbed out as if a rocket were strapped to his back.

Conscious of the wires around three sides of my landing zone, I took off on the fourth side, heading right over the river. I didn’t climb much; once I was over the cliff, I was already at least 500 feet over the river. I flew downriver at that altitude for a while. I wanted to follow the river all the way back, but there was a fire burning near Wenatchee and I’d forgotten to call the FSS to see if there was a TFR. So I figured I’d just go down the river a bit before I climbed back up to the Plateau and made my way back that way.

Powered Paraglider

You can find this photo of a powered paraglider on Wikipedia.

I saw the other paragliders first. There were at least five of them, flying in lazy circles about 200 feet above my altitude, to my left. They were close enough to see their colorful canopies, but not close enough to see whether they were powered. But I didn’t look long. Movement much closer caught my eye and I spotted one at my altitude less than 1/4 mile away.

I swerved to the right, away from him. I then kept scanning the airspace all around me, looking for others. Thankfully, I came up empty.

My onboard video camera caught the action. This is a clip from the flight. The paraglider is in the picture right from the beginning. Look slightly right of center near the top of the frame. His canopy is yellow. I spotted his friends at about the 0:09 mark and banked a bit to the right; I spotted him at 0:15 and made a more aggressive turn.

The quickness of this encounter (or near encounter) is quite evident in the video clip. The video is only 20 seconds long. When you’re moving along at 120-130 miles per hour, things happen fast. It turned out, he was going the same way I was — and I’m pretty sure he was powered — so he probably didn’t even hear me coming up behind him. At his near-stationary speed (when compared to mine), I was upon him only seconds after he came into view.

I am not accustomed to seeing any aircraft other than helicopters at my altitude, so to say that this shook me up a bit is an understatement. Just because you don’t expect to see something doesn’t mean it isn’t possible.

No More Mishaps

The rest of the flight was uneventful.

I climbed up to the Plateau, crossed over the big wires, and settled down for another relatively low flight across the wheat fields. I took a detour later on, following a canyon down into Lower Moses Coulee, over the town of Palisades and out over the Columbia River south of Wenatchee and its fire. I flew low-level along the eastern shore of the river to Crescent Bar, then climbed up to the Babcock Bench to scout out a geocache location up there. From there, I flew out to Quincy Lakes, overflew the Ancient Lakes and their waterfalls, scouted another geocache location, and headed back to the ag strip where I’m based until July 20.

I’d flown a total of about two hours. It was my first time out flying in two weeks. (I sure wish it would rain again soon — if only to wash the dust off the helicopter.)

It was good to get out — and good to get shaken up a bit. I’d seen two instances of complacency rearing its ugly head. Fortunately, no injuries; just lessons learned.