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Old 21st Feb 2008, 14:09
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SNS3Guppy
 
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SNS3Guppy this will probably make you laugh but...
I thought ag flying was just whizzing up and down a field at low level spraying some sort of chemical out the back.
I think that's the common perception of ag flying. In the most simple analysis, you're correct; when doing row crops, one does in deed "whizz" up and down the field at low level, generally spring chemical of some sort. It's not, however, a cowboy endevor. It tends to be very precise flying, and typically requires a high degree of professionalism. It may be one of the few vestages of barnstorming left, but it's also become a tightly regulated industry with some very big obstacles such as regulation, litigation, and perception in the public and private sectors. Today an ag pilot seems as much recurrent training as any corporate or airline pilot, but performs a much greater percentage of his or her time actually flying the airplane and in the critical phase of flight (all of it).

Some of the aspects relevant to the ag pilot are the flying...which can involve steep turns very close to the ground, and very close to the stall, often at maximum weights, often in unfavorable circumstances (and in the context of this thread, at night). Ag pilots are also entimologists, being familiar enough with the insects (or weeds and crops) that he may treat that he can take samples and make recommendations for treatment. He needs to know as much about every crop he may treat as the farmer. By default therefore, the ag pilot needs some expertise in crop and farm science. He needs to understand the chemicals with which he works. Drift is a big issue; a chemical applied in a field can affect vulnerable trees, water or crops miles away. Environmental issues are always a concern. The ag pilot is very often also a mechanic (or engineer, as the term moves you).

Today most ag operations are performed to very tight tolerances using GPS equipment and external lightbar displays which work very similiarly to a localizer, but much more precise. A failure to maintain an exact height and an exact track over the ground means that skips in coverage in a field occur. These skips can cause reinfestation of insects, or allow weeds to devalue or destroy a crop, or simply cause a farmer to not pay the ag pilot. It only takes one claim to put a pilot out of business, or cost the profits for the entire season. With chemicals at a thousand dollars a gallon in some cases, mistakes can be very costly. To say nothing of ensuring that you're spraying the right chemical for the right farmer on the right crop...when you're in an area of several thousand acres that all look alike, that's not always as easy as it may seem.

This is done in varying wind conditions, often with a variety of obstacles ranging from other airplanes to standpipes, farm equipment, powerlines, trees, etc. Monitoring the application while maintain a very exact track and altitude, while maneuvering to avoid obstacles, and doing so with frequent steep turns close to the stall at 75' or so can be demanding, as can be the long days, the working conditions (which are usually not gentle), the exposure to a variety of chemicals which are akin to VX or Sarin in their lethality and content, frequent takeoffs and landings, and constant operation at the performance limits of the airplane.

Chemical application into a field is often over obstacles, leaving a segment near the edges of the field which must be "cleaned up" after the field has been treated. These clean up passes are very close to obstacles...often entailing a pass with the wingtips within a few feet or so of powerlines, telephone poles, fence lines, irrigation equipment, etc. Any drift toward that eqipment has dire consequences. This goes on day in and day out, without autopilot, in aircraft that are only trimmable in the most rudimentary way and which experience a constantly changing center of gravity thorughout the course of the flight. Consistant application is critical, and the pilot must monitor the rate of material loss while monitoring the nozzles themselves out of his perepherial vision to ensure no "streaking" nozzles that might cause damage or drift. He is also liable for benificial insects, cattle, persons, and property in and around the fields, at all times.

That's a little bit of the "whizzing" about...but it's definitely a lot more technical than simply flying and dispensing material.

What would be the brief you get etc...
You don't normally get any briefing.

There are a lot of different kinds of ag flying. Some of the kinds I've done include spraying row crops, seeding, fertalizing, and other work related to crop treatment. I've also performed range control, and right of way treatment, spraying over roads and across range land where noxious weeds which are hazardous to people or cattle might grow. I haven't done it, but aerial baiting for pests such as rodents or coyotes is also done. I've flown a lot of firefighting using single engine tankers, and large multi engine air tankers. This is also very much a segment of the ag industry. I've flown turbojet aircraft such as the LR35 doing aerial work penetrating thunderstorms for research and treatment, cloud seeding...also ag work, but of a very different sort. The nature of briefing and preparing and performance of the mission is very different in each area. Some flights have been nothing more than survey flights, some perepherial flights also related to ag work have been aerial surveillance of illegal dumping of chemicals and law enforcement flights of resources like Christmas trees or illegal logging. I've also done fire patrol and aerial command and control, sometimes called "air attack" or "bird dog" work. All ag functions but very different in their nature.

Work such as firefighting is done in very mountainous terrin, often in strong turbulence that's frequently severe or greater. It's often done in diminished visibility, frequently close to other aircraft, and comes with it's own unique hazards. I've also done it at night, thought that's an unusual circumstance. I dropped adjacent to Disney World in Florida at night about ten years ago in large air tankers during some well publicised "fire storms" in that state.

In the case of firefighting, we get dailing briefings regarding fuel moisture, expected weather, relative humidity, lightening potential, various indices, winds, available resources, etc. Those kinds of flights often involve integration between multiple agencies, and close and formation flight betwen vasty dissimiliar aircraft, so coordination and breifings between different components of the operation is also necessary. Conversely, if you're seeding a remote area after a fire, at the end of the season, then the only briefing going on may be between you and your loader, and it's more of a safety and efficiency briefing on how best to accomplish the mission. You may also get briefed by the contracting agency, which will be taking GPS readings of your mission to see exactly what was done and where. Very close oversight.

How low would you be flying, is the lower the better?
That really depends on what you're doing. If you're seeding, you may be flying at 15 to 30' above the surface. If you're putting out a volatile chemical with a high drift and damage potential such as 2,4-D, then lower is often better...but not too low. Some chemicals benifit from the turbulence created by the wake of the airplane to circulate thoroughly through the crop and to penetrate the crop canopy. Others need to settle their forward motion and fall straight down. In the case of fire retardant, specific minimimum altitudes are established for several reasons. Safety is one. Effectiveness is another. If you're treating fuels with a fire retardant material, then you want the retardant to stop moving forward and start falling straight down in order to coat all sides of the fuel. Otherwise you just get the side from which you approach, and the fuel will still readily burn. This typically requires a drop height of 50-60'...but I've been asked to put one wheel on the burn in conditions of high winds and drift in order to keep the retardant from drifting off the fire. In heavy tankers, traditionally we've used 200' as the minimum drop height, and I've seen it raised to as much as 400' when dropping on extremely fragile and brittle fuels.

Airspeed control is important. Moving down the field you're effectively in "cruise." Power is applied to climb out of the field and turn, and reduced when re-entering the field (in a dive, if over obstacles). While it involves a steep turn at the end of the field in many cases, the turn is treated the same way as a very rapid, high performance traffic pattern, with a stable approach at the end back into the field. It's got to be done precisly so as to be on track with the proper spacing. It can't be too fast, or the calibration of the applicatio is put off; the chemical will be too thin and may not work. Too slow and the amount of chemical put out increases. Airspeed, along with all other parameters, must be accurate.

How many fields would you do in a day?
That's really quite subjective as to what is being put down and what's being treated. If it's dry fertalizer or seed, you may make twenty or thirty loads and cover very little acerage. It's never really a matter of what fields are being sprayed or treated so much as it is how many acreas. If you're doing low volume work, such as one or two gallons per acre, you can treat a lot of acreas with a load of material. If you're doing high gallonage work, such as ten or fifteen gallons to the acre (or pounds/kg if you're dealing in dry material such as seed or fertalizer), you may be doing a lot of flying with very little acerage covered...a full load treats far less. This is typically the case when doing fertalizer work on pine tree plantations, for example.

Conversely, mosquito abatement is a big thing in some urban areas. Aircraft that range from ag airplanes to Beech 18's, Navajos, etc, put out Ultra Low Volume (ULV) levels of chemical that can be as little as a few ounces per acre. Often these directly treat waterways and areas of standing water, and and are often done in the early morning or dusk, or even close to night or at night, and may involve long flights with a single load of material. How much you cover and how much you put our really depends on the assignment, what you're flying, where you're flying, the weather, etc. I've done thousands of acres, and just a few acres. I've also done treatement such as fires in which we were paid by the hours on the airplane, and the agencies measured the success based on gallons brought to the fire. In those cases it just depends on what you're flying, where you're flying it to and from, and the distances involved.

For fires I have to typically go to five or more schools each year. These can range from a day or two to a week or more, and in one case, it's an internet course thats' taken annually. Aerial applicators in the USA are also required to participate in most cases in ongoing education, accruing so many hours of continuing education each year as part of keeping up certification. This includes legal training, chemical training, flight training, crop and insect training, etc.

You're absolutely correct that ag flying is whizzing back and forth spraying chemical...but in it's application, it's so much more.
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