ARESTI: THE LANGUAGE OF aerobatics
When aerobatics first came into being in the 1920s, there was no good method for pilots to explain to others what they were going to fly. Some used their own method of shorthand notations, others would describe the maneuver with various words and phrases. But as the sport of aerobatics began to mature and spread into international competition, the need for a standardized method to describe aerobatic flight maneuvers grew due to language differences.
In 1961, the Spanish pilot José Luis de Aresti published an aerocryptographic system to describe aerobatic maneuvers that broke down individual pieces into lines, curves and rotational elements. This Sistema Aresti, or Aresti System, was adopted by the Fédération Aéronautique Internationale (World Air Sports Federation or FAI) as the official method of aerobatic sequence description at the World Aerobatic Championships in Bilboa, Spain in 1964. Today, the Aresti System – called Aresti for short – is in use worldwide. It allows a Russian pilot to fly a U.S. sequence in front of an Italian judge and no one needs to speak a foreign language to make it happen!
At first glance, Aresti may look like complicated hieroglyphics. But if you understand the basic notations and rules, it becomes a much clearer picture to read and speak.
An introduction to the origin and basic organization of the Aresti Aerocryptographic System describing aerobatic flight programs by the IAC.
For starters, each figure begins and ends with a horizontal line of flight that may either be upright or inverted. The figures will be numbered in the order in which they should be flown, and the start of a figure will have a black or open dot and at the end, a bar.
Competition sequences will be designed to be flown inside the confines of the Aerobatic Box, so the figures will switch directions across the page (and in the air) every two to three maneuvers. Figures are drawn in 2D – left/right, up/down – but the actual flying uses a third axis, to/from. To show a change to the “crossbox” or y-axis, it takes a 1/4 or 3/4 rotation to switch from x to y, and the end bar of a figure flown on this axis will be horizontal, instead of vertical.
This is an Intermediate sequence which shows all of the above.
Lines represent three modes of flight: horizontal, vertical or at a 45° angle. Upright or positive g flight lines are solid, while inverted or negative g lines are dashed and red if color is used. Upright or inverted only describes horizontal lines (or spins). Positive g or negative g describes what is happening to the g-loading of the plane on the other lines and curves and can be thought of as what the pilot is experiencing: are they being pushed down into the seat (positive) or do the feel like they are being “thrown” out of the seat toward the canopy (negative)? Even though a plane flying a loop is inverted on top, it is still a positive maneuver because there is positive loading and a positive angle of attack on the wings.
Circles and partial circles or curves drawn with solid or dashed lines, represent full loops and partial loops from 7/8 to 1/2. Turns look like circles on their sides, can be upright (solid) or inverted (dashed), and will be drawn as 90°, 180°, 270° or 360° of heading change.
To these lines and circles, other symbols can be added to represent rotational elements: rolls, spins and snap rolls. An aileron or “slow” roll is represented by a curved arrow, and a number may be added to indicate “point rolls” – where the pilot pauses then continues the roll, like the hands of a ticking clock – such as 8-point, “8”, or two of four quarters, “2x4”.
Spins are represented by long, right triangles, and snap rolls are shorter, equilateral triangles. The triangles will be empty/not filled for upright spins and positive snaps, while black or red-filled triangles represent inverted spins and negative snaps. If the arrow or triangle crosses the main line, it indicates a full rotation. If it is drawn on only one side of the line, it shows a partial rotation, which is assumed to be 1/2 unless there is an additional written notation indicating a 1/4 or 3/4 turn.
These arrows or triangles can be combined to indicate more than 360° of rotation and the tips of the symbols will be linked by a small line. However, if the arrows are pointing in opposite directions on he main line, then this indicates separate elements which must be flown in opposite directions back to back. A maximum of two sets of rotational elements are allowed on any one line.
Each figure and optional rotational elements has a “K value”, or point value, and a catalog identifier number. For example, a plain horizontal line has a k of 2 and an ID of 22.214.171.124. Add a half positive snap, k of 11 with an ID of 126.96.36.199, and the overall figure has a point value of 13.
In competition, the K value is multiplied by the judge’s score that ranges in .5 increments from 10 (perfect!) to 0.0 (so badly flown they ran out of points). So if a judge gives a competitor a 8.5 on the line with a half positive snap (188.8.131.52 + 184.108.40.206) with a k=13, the final point value is 110.5 of a possible 130. This process is repeated for every figure and every judge, with the overall ranking of a pilot in the flight determined by the overall percentage of points won out of the total points possible.
The Aresti System is organized into families of similar maneuvers. The families of figures are defined as follows:
Family 1 – lines and angles
Family 2 – turns (including rolling turns)
Family 3 – combinations of 45° and vertical lines
Family 4 – no longer used
Family 5 – hammerheads
Family 6 – tail slides
Family 7 – loops and eights
Family 8 – combinations of lines, angles and loops
Family 9 – complementary rotational elements
There is an in-depth exploration of these families, Aresti and its rules over at the IAC site written by Brian Howard if you’d like to understand more. The most up-to-date full Aresti catalog may be ordered from Spain (it is copyrighted and not available online).
Head over to the Competition Levels page to have a look at various sequences flown at the different levels of experience.
If you are an EAA member, IAC Unlimited team member Jim Bourke presented a webinar in 2020 entitled "How to Read and Call an Aerobatic Sequence" which will provide more insight on how to understand and verbally describe Aresti figures while working as an Assistant Judge during a contest. EAA member login required: https://eaa.org/Videos/Aerobatic-Aircraft/6142568798001
by Susan Bell, IAC #438132