Glossary
Effective Swath
The usable working width of a single drone pass — narrower than the raw spread width — set so that overlap from adjacent passes produces an even, gap-free application.
Definition
A spreader or sprayer throws product across a total width, but the deposition is heaviest in the middle and tapers at the edges. The effective swath is the narrower width you actually advance between passes so that the tapering edges of neighbouring passes overlap and sum to an even rate. Set the swath too wide and you get striping — under-applied lanes between passes; set it too narrow and you waste time and product on excess overlap. Effective swath is determined by pattern testing for a given product, rate, height, and wind, not by the spec-sheet number. The pan test that sets it is a defined sequence: lay a line of collection pans across the full throw width, fly a single pass over them, weigh the catch in each pan to map the deposition curve, find where the edges taper, then set the advance width so neighbouring passes overlap into an even total — and re-run the test whenever the product, rate, or release height changes.
In an Alberta Context
Granular products (fertilizer, cover-crop and forage seed) and Alberta’s open-field wind both shift the real effective swath away from the brochure figure. A pan test or known calibration for the specific granular product being flown is what keeps a drone spread even across a quarter — striping shows up clearly at green-up and is expensive to explain to a grower after the fact. UAV AG’s working wind policy is to narrow the swath or pause as wind rises rather than push a pattern that will streak. This calibration is for granular spreading — fertilizer and seed — which is the legal drone service in Canada today. Pesticide application by drone is a separate matter, now under a narrow interim pathway following PMRA’s June 2026 Letter of No Objection.
Why It Matters
Effective swath is the single setting that most determines whether a drone spread looks professional or striped. Getting it right is the difference between an even stand and a field with visible tramlines — and it is the kind of calibration discipline that separates a credible custom operator from someone who just bought a drone.
Frequently Asked Questions
+How do you determine the effective swath for a job?
By pattern (pan) testing the specific granular product at the planned rate and height: lay out collection pans across the spread, fly a pass, weigh the catch per pan, and set the advance width so neighbouring passes overlap into an even total. The brochure swath is a starting point, not the setting.
+Why is the effective swath narrower than the spread width?
A spreader throws heaviest in the centre and tapers at the edges. You advance less than the full throw so the tapering edges of adjacent passes overlap and sum to an even rate. Use the full spread width and you get under-applied stripes between passes.
+How does wind change the effective swath?
Wind skews the pattern and shifts the deposition off-centre. UAV AG’s policy is to narrow the swath or pause as wind rises rather than push a pattern that will streak — an even field is worth more than a fast one.
+Does granule type affect the effective swath?
Yes. Granule size, density, and humidity all change how far and how evenly a product throws, which is why the pan test is done for the specific product being flown rather than assumed from another blend.