I recall a sales pitch for car polish that said, “Use this product and the only surprises you’ll get are pleasant ones.” That sounds good, but I prefer to have no surprises at all when flying.
This is particularly so during aerial application. A telephone wire suddenly appearing ‘out of nowhere.’ A particularly violent gust of wind on short final. A clogged pitot tube from a bug ingestion that renders your ASI useless. The question becomes how we can eliminate or at least minimize the effect of such ‘surprises’ that can make for a bad day at the office.
It’s often not what we know that gets us into trouble. It’s what we don’t know that can really get our attention. We all have blind spots in our knowledge base, regardless of experience level or familiarity with aerial applications. How can we effectively deal with these blind spots?
One route is reading and studying incident/accident reports readily available from aviation agencies and regulators. Put yourself in the cockpit and imagine what your response would be to the given scenario. Just as important, think of ways that you could adopt to avoid firsthand experience of a particular situation.
Along the same lines, I find that sharing stories and experiences with fellow pilots can be a great help in avoiding potentially dangerous situations. Through my years of flying, I have been very fortunate to have met several seasoned ag pilots who were more than happy to share their knowledge with me. In this spirit of sharing information, the following are a few scenarios I’ve personally experienced that hopefully will be of interest to pilots at all levels. An ounce of prevention is worth a pound of cure.
Fatigue
The sinister and dangerous specter of fatigue comes high on my list as a serious contender for first place in causative factors for accidents. One of my first dramatic experiences as an ag pilot was flying a Super Brave in coordination with two other aircraft and pilots during a hectic season. If it wasn’t weeds, it was bugs; if it wasn’t bugs, it was fungi. To boot, it seemed as if Mother Nature was tagging up with the gods of aviation by providing ideal application weather all day long. It set the stage for some very fatigued and tired pilots.
That’s when I got ‘the nods,’ a term very familiar to those who drive long distances. You momentarily fall asleep at the wheel, which is dangerous enough on the ground. In the air, it can be fatal. In my case, I had a very brief excursion into la-la land during the last spray pass on a wheat field. Halfway through the pass, the mains contacted the ground, and the aircraft responded with a decidedly violent bounce. Luckily the crop was short, and the only effect was to scare the daylights out of me. I reoriented myself, finished the final pass, headed home, shut the aircraft down, and took a good long nap.
Why did I let fatigue get the best of me? It was because we were faced with an onslaught of pests, and no one wanted to be the first to say “enough is enough,” instead depending on gallons of coffee to do the trick. Caffeine might help keep you awake, but alert and responsive is something else.
I discussed what had happened with the ground crew and the other two pilots, all of whom said they had thought of shutting down but didn’t want to be the ‘wimp.’ We all agreed to keep closer tabs on our collective ‘awakeness’ from then on and never ever feel uncomfortable saying “No!”.
Specific Gravity Will Get You Every Time
As we learned in high school physics, specific gravity (SG) relates the weight of a liquid compared to the weight of water. Given that a gallon of water weighs around 8 lbs, a gallon of liquid fertilizer with an SG of 1.285 would weigh 1.285 x 8 lbs = 10.28 pounds.
It doesn’t sound like a big deal until you take a hopper full. The majority of pesticide tank mixes are roughly the same weight as water alone. If you are using 360 gallons as a standard load, it would weigh 360 x 8 = 2,880 lbs. The same volume of liquid fertilizer would weigh 360 x 8 x 1.285 = 3700 lbs., equivalent in weight to 462 gallons of water!
Think of the surprise you’d get trying to take off with that load. It certainly caught my attention as I was doing just that in a 600 HP Thrush S2R. I immediately knew something was wrong due to the lethargic acceleration. Initially, I thought I had lost a cylinder and aborted the takeoff. Once back at the loading area, I had a good look at the label, and sure enough, there it was, a specific gravity of 1.285. Once I got my breath back, we unloaded the hopper to 280 gallons (reducing the weight to 2880 lbs) and used that as the standard load with the product we were using.
Catch You From Behind
Anyone who has dealt with a low-level wind shear knows about this surprise in the sky. When flying downwind at application height and you pull up at the end of a run, your airspeed rapidly unwinds as you climb into an increasing tailwind. The controls feel mushy, you are too close to stall for comfort, and you’re a bit miffed the situation caught you by surprise.
One avoidance tactic is to make it a habit to note branch movement at the tops of trees en route to the field. If they are really active compared to a very light surface wind, give yourself plenty of leeway once you start spraying. Spread the word back at home base and take a moment to examine the situation critically. If it looks too hazardous, it’s time to hang up the spurs for the day.
Many such situations can really invite some surprise moments – the kind that you don’t like. Inversions. Tree rows making powerlines challenging to see. Low into sun visibility. Power loss at low level. There are many challenges, but by staying alert, strictly adhering to safe flight principles, and making it a habit to share ‘surprise’ moments with others, you’ll go a long way to ensure all operations are safe and effective.
