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  #1  
Old 03-17-2013, 08:27 PM
Chris Hill Chris Hill is offline
 
Join Date: Sep 2010
Location: Del Rio
Posts: 124
Default Safety Discussion #2: Low Altitude Flight

I expect this to be a hot topic, so please abide by the following guidelines for this discussion in order to keep it civil:
1) If you know any of the people involved in the video or the accident, please do not identify them.
2) If you are any of the people involved in the video or accident, please do not self-identify.
3) Do not enter into personal debates/general philosophical discussion in this thread. Please use the PM system or start a new thread for those types of discussions.

The purpose of this discussion is to talk about the risks associated with the low altitude flight environment and how to mitigate those risks. For the purpose of this discussion, low altitude will be defined as less than 1,000ft AGL. Encouraging/discouraging flight in the low altitude environment is NOT the purpose of this discussion.

THIS IS NOT A LEGAL DISCUSSION. While some of these accidents may appear to be violations of the FARs, keep in mind this is a safety discussion and the video/accidents are presented as examples of scenarios where people have crashed in a low altitude maneuvering environment.

That being, said please read the following accident reports and watch the following video:

Accident #1
Summary: Low altitude flight (200-300 ft) resulted in controlled flight into terrain. This one might lend itself to a discussion of visual illusions at low altitude over water.

Accident #2
Summary: Low altitude flight (500 ft) resulted in controlled flight into power lines.

Accident #3
Summary: Low altitude flight (less than 900 ft) at night resulted in controlled flight into terrain.

Accident #4
Summary: Low altitude ?buzz? followed by a steep pull up resulted in out of control flight into terrain.

Accident #5
Summary: Aggressive low altitude flight resulted in out of control flight into terrain.

Treetop Flyer
Summary: Successful low altitude river run. What you can?t see here is what preparation (if any) was done prior to flying this route. I offer this as an example of someone who successfully flew in the low altitude environment and made it look easy. Don?t let a video persuade you to fly in a regime in which you have not properly prepared yourself to fly.

I could keep going?but I think these scenarios provide examples of the most frequent types of low altitude crashes (excluding takeoff and landing). My brief and unscientific estimation, based on looking at NTSB reports, is that this type of accident accounts for about 10% of all RV accidents. Regarding low altitude flight safety, there are probably 10 pages of legitimate discussion on how to reduce risk, so hopefully we can have a good discussion on ways to fly low altitude and do it safely.

I?ll start with some topics which might be addressed by some resident experts on the forum (not all inclusive):
Visual Illusions
Visual Illusions over water
Restricted visibility
Multi passenger Flight Characteristics
Night time low altitude flight
Bird Strikes

RVs readily lend themselves to low altitude flight because they are fast and have above average power to weight ratios. I suspect this leads many people to enter into the low altitude regime too casually from thinking that the airplane performance will keep them safe. Any time I am going to fly low, I thoroughly review the route of flight to check for obstacles. Start with a good map, and look for anything which might be a hazard to you on your route. Make a note of the altitude required to avoid those obstacles by a safe distance. Is it a good idea to fly near cell towers or radio towers? Nope. Not only due to the fact that the tower itself can cause you to crash, but the tower also has wires that help hold it up and which are very difficult to see until it?s too late. So first, start with a good route study on the ground. Once you have a feel for the path along the ground which you want to fly, go scout it out from a much higher altitude where you can see the whole picture around you and not have to worry about inadvertently crashing while you are checking the route. After you have done that, you are better prepared to decide if you really want to pursue flying low in that area.

Hopefully this is enough to get the discussion started. Remember, focus on techniques to be safe as you post in this thread.
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  #2  
Old 03-17-2013, 09:26 PM
terrykohler terrykohler is offline
 
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"RVs readily lend themselves to low altitude flight because they are fast..."

Let's think about this- If faster is better for low altitude flight, when I feel like flying really low, I should leave the cub in the hangar and take the citation?
Terry, CFI
RV9A N323TP
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  #3  
Old 03-17-2013, 10:56 PM
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newt newt is online now
 
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Location: Sydney, Australia
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Video of low altitude flight through river valleys scares the heck out of me. Valleys always have wires hanging from one side to the other, waiting to catch pilots who haven't seen them.

Not sure how electricity is distributed to farmhouses in the USA, but in Australia it's very common for utilities to use Single Wire Earth Return (SWER) systems.

SWER systems use a wire about the same gauge as fencing wire to carry 12.7kV on wood or steel/concrete poles about a quarter mile apart over distances of anything up to 30 miles.

The utilities seem to try their best to make the poles visually unobtrusive by putting them in groves of trees or scrub, or along existing fence lines where they won't interfere with agricultural machinery. And the wire is tiny, essentially impossible to see. Generally the only way you'll know they're there is by looking for a characteristic teardrop pattern around the base of each pole caused by the farmer's plough diverting around it, then by scanning out by approximately a quarter mile to find the next pole... And the next... And the next. But even that cue is absent if the poles are on fence lines or in trees.

And even then you won't know if you've found them all because the wires sometimes branch from poles to feed multiple nearby properties. Maybe you've missed a branch!

The upshot is that even flat, clear-looking, isolated terrain miles from civilization can be cross-crossed with wires on almost invisible 30 or 40 foot poles.

I know of at least one fatality caused when a pilot recovered an aircraft from an off-field landing in a valley. There was an unseen SWER line in his takeoff path; one pole was on the crest of the hill on one side of the valley, the next was on the crest of the hill on the opposite side, and the wire hung invisibly in an arc between them. Nobody knew it was there until the aircraft hit it.

So yes: low flying is so far below my personal minimums that it isn't even on the agenda. Except in very limited situations which I'm never likely to encounter in my flying career (such as well surveyed crop duster ops, perhaps), I just don't see how it can be done safely in my part of the world.


- mark
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  #4  
Old 03-17-2013, 11:46 PM
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SMO SMO is offline
 
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Default Treetop Flyer link

Treetop Flyer link doesn't work for me, this one should do it:

http://www.youtube.com/watch?v=o40_MzuKIGA
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  #5  
Old 03-18-2013, 05:22 AM
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panhandler1956 panhandler1956 is offline
 
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Location: Ohio
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Quote:
Originally Posted by newt View Post
Video of low altitude flight through river valleys scares the heck out of me. Valleys always have wires hanging from one side to the other, waiting to catch pilots who haven't seen them.


- mark
This one almost got me as youngster. I was out on a training flight in a C-152 and impulsively dropped down into a river (just like the video). Luckily, I climbed slightly because of an upcoming bend because I didn't see the wires, that I missed by a few feet, until they went under me - talk about scary.
That cured me.

Good post Chris!
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  #6  
Old 03-18-2013, 05:38 AM
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pierre smith pierre smith is offline
 
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Default This is my regime.

Ok, time for me to chime in.

I make my living well below 1,000' and I'm here to tell you, after 43 years of doing this, it gets harder every year because of

A) In the mid-west mainly, the erection, overnight, of MET towers. These are Meteorological Evaluation towers that spring up overnight to evaluate the feasability of putting up a wind farm there...how many hours of such and such a wind strength, etc...they're just below the 200' requirement, so they don't have lights.

B) GPS towers in farming areas. I have had so many close calls with these 199', unmarked, grey towers that provide farmers GPS enhanced signals in order to have sub 2" steering accuracy (Yep, two inches!) for their autosteer device that steers their tractors and sprayers.

Our National Ag Aviation assoc is working to mark both the MET towers and these GPS towers with alternating red and white bands and also orange balls on those almost-invisible guy wires.

We've already had a fatality last month, when a 53 year old highly experienced ag pilot hit guy wires with an 800 gallon Dromadier.

You're taking your life in your hands when you venture under 1,000' out in the countryside where it APPEARS so safe and tranquil. That's exactly where you'll find MET and GPS towers.

I used to fly under bridges and cables on the Savannah river back in the '70's when I was young and bulletproof, in the Supercub that I sprayed a couple of lakes for mosquitoes with...but older and wiser shows how foolish low-level river runs can be.

Best,
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  #7  
Old 03-18-2013, 08:26 AM
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Alan Carroll Alan Carroll is offline
 
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The 12/93 edition of the RVator printed an interesting first-hand account of low flying, that had been sent in by a reader. This pilot claimed he had "on more than one occasion" flown 200 mile cross countries at 15 feet AGL and 200 mph, climbing only to avoid power lines or as required by 91.119. Presumably cell towers, MET towers, etc. were less of an issue then, but this account nonetheless made the hairs go up on the back of my neck.

The rationale for including this in the RVator was that some pilots will do this sort of thing even if told not to, so they might as well learn to do it right. Van, who wrote a short lead for the article, seemed a bit uncomfortable with this line of thinking, but allowed it to be published.

It seems to me that this example illustrates a general phenomenon that is often downplayed in safety discussions: the "fun factor" of RVs often leads to flight regimes rarely visited by the Cessna crowd. Ignoring this fact is unrealistic, but what is the right balance between safety and the realities of sport aircraft?
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  #8  
Old 03-18-2013, 08:41 AM
terrykohler terrykohler is offline
 
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Default Thanks Pierre!

"You're taking your life in your hands when you venture under 1,000' out in the countryside where it APPEARS so safe and tranquil. That's exactly where you'll find MET and GPS towers."

The pilots that think rules such as FAR91.119 don't apply to them or are open to interpretation are the type of pilots that need them the most. Altitude is a lot like fuel - in most cases, the more you've got, the more options you have. Can I conduct an instrument flight with FAR minimum fuel knowing my primary and alternate are both at allowable weather minimums? Sure. Will I be comfortable if a don't have other options? Not a chance.
When highly experienced pilots such as Pierre warn against low flight (and do it for a living) it's time to pay attention.
Promoting or encouraging this type of flying, particularly amongst weekend pilots, is really contrary to the interest of safety.
Terry, CFI
Rv9A N323TP
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  #9  
Old 03-18-2013, 08:50 AM
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RV7Ron RV7Ron is offline
 
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Thanks Chris, I'm loving this new approach to talking about RV-specific accidents...keep 'em coming.

One thing I noticed...all five accident reports had two on board. Maybe some "watch this" showmanship involved? Just a thought...
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  #10  
Old 03-18-2013, 08:52 AM
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DaleB DaleB is offline
 
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I can see how the flying done in the Treetop Flyer video (which I love watching, by the way) could be done with some degree of safety, at least from wire and tower strikes. The first time I saw that I said to my wife, "I sure hope that guy regularly canoes or walks that area and knows for sure there are no obstructions. Otherwise it would be a crazy-stupid thing to do".

Stuff like that is far outside the envelope of anything I'd try. I can see how someone who knows the area very well, and checks it regularly, could do it without killing himself...

at least a few times.

If that big fan quits, though, it's going to get very, very uncomfortable in a big hurry.
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