I recall a sales pitch for car polish that said, “Use this product and the only surprises you’ll get are pleasant ones.” Which sounds good, but when flying I prefer to have no surprises at all.
This is particularly so during aerial firefighting missions. 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 firefighting. How can we effectively deal with these blind spots?
One route is to read and study incident/accident reports that are 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. I have been very fortunate through my years of flying to have met a number of seasoned 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.
The sinister and dangerous specter of fatigue comes high on my list as being a serious contender for first place in causative factors for accidents. One of the first dramatic experiences I had as an ag pilot was flying a Super Brave in coordination with two other aircraft and pilots during an extremely busy season. If it wasn’t weeds, it was bugs, and if 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 really 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 just 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 and finished the final pass, headed home, shut the aircraft down, and went for 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 just what had happened with the ground crew and the other two pilots, all of whom said they too 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 to 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 with an SG of 1.285 would weigh 1.285 x 8 lbs = 10.28 pounds.
Doesn’t sound like a big deal, until you take a tank full. The majority of 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 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 drop 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 have a critical look at the situation. If it looks too hazardous, it’s time to hang up the spurs for the day.
There are many such situations that can really invite some surprise moments – the kind that you don’t like. Inversions. Tree rows making powerlines difficult to see. Low into sun visibility. Power loss at low level. The challenges are many, 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 ensuring all operations are safe and effective.