The good news about existing FAA kite regs
is the huge loophole for lean systems under 5lbs. The only strict
requirement for a lightweight kite is to not operate in an unsafe
fashion, which still requires expert judgment. Anyone able
to design (& properly justify) safe remote experimental
operations is in the clear. Its likely this loophole will close
considerably as the NextGen Airspace overhaul occurs.
Given the safety,
reliable dynamic similarity, & agile-engineering power of
scale prototypes its a laugh to see AWE "dinosaurs" slowly
struggle with oversized foundational science experiments. It is
possible to legitimize scaled-up AWE R&D under cover of related
approved activities like aero-tow. For those who understand
how to use fully certificated aircraft & pilots in a
convincingly safe manner, the AWE dimension remains outside of
regulation. The downside of relying on just two
NASA airspaces is that no AWE R&D player is based at those
locations & NASA is surely qualified & obliged to enforce
most of the same general safety culture & restrictions as the
FAA. The key for real developers is to build up many years worth
of flight-test hours & limited demo-dates at NASA don't do that.
Below is the latest KiteLab/AWEIA
regulatory framework document (paste-job messed up formatting), if
anyone has input to add prior to a 1.0 version intended for
Tethered-Aviation ConOps (TACO)
Focus on Experimental Airborne Wind Energy (AWE)
Proposed FAA Advisory Circular
Proposal for Action- ICAO Standards And Recommended Practices (SARPs)
Note to the TACO 7th Draft-
At the second Airborne
Wind Energy (AWE) Conference (AWEC2010), the attending FAA
official publicly called for the early industry to
define the emerging aircraft types into the FAA's Category
& Class system. For its part NASA informally tasked industry
players with developing ConOps frameworks for AWE in the US
National Airspace (NAS).
The Airborne Wind Energy Industry Association (AWEIA) responded by
initiating this report addressing requirements. KiteLab Group,
an AWE R & D pioneer, volunteered to compile a master
Tethered Aviation ConOps (TACO), in an open collaborative process.
TACO is intended as an FAA Advisory
Circular to inform aviation stakeholders of the issues.
While AWE is the priority application of this ConOps, the
full scope is TA as a whole. Not only are
there exciting new kinds of TA, bit there is a vast pool
of historic TA precedent & working models to apply to AWE
operations. T ethered or not, persistent acceptance-barriers exist to autonomous aviation in the US NAS (National AirSpace). The current FAA requirement for piloted systems will hold for some years.
Thus this early-stage TAConOps Draft is "pilot-centric", embracing
the pilot's key stakeholder status, but also is forward-looking
toward eventual flight autonomy (Appendix).
As a major future energy technology, AWE has the potential
to subsidize many of the dreams of aviation planners & general aviation.
This document is intended to evolve & merge
into the NextGen Airspace ConOps. The US
(FAA) regulatory standard is expected to drive the international
picture (ICAO, etc). Send corrections, additions, &
comments to firstname.lastname@example.org
(add definitions) AKA AOPA AMA AWE AWEIA AWEA ConOps FAA FARs ICAO NASA R&D SARPs TA TACO sUAS UAV
Tethered Aviation is an old & important branch of Aeronautics, with a erostats, aerotowing
, & kites as well-known examples. New tether-based
flight systems under development will enhance conventional
aviation capabilities, host infrastructure (ie.
communications), spin-off industries, create recreation,
& generate clean energy. This "New Aviation" requires the primary
stakeholders, pilots, developers, regulatory bodies, &
populations, to come together to resolve technical & social
challenges & realize the great potential. For the immediate
purpose of private R&D, the current system is not broke;
change by small increments grows over time into
major mature sectors.
are a key stakeholder, as primary users of airspace most
exposed to flight risk. Following aviation norms &
traditions, pilots will lead safe effective Tethered Aviation
R&D, fill jobs in the new aviation industries
& ensure safe operations consistent with shared airspace. The
aerospace industry tasked with designing systems that pilots accept
& the FAA can certify as airworthy. Policy developers &
decision makers, from the national to the local level, are another
key stakeholder group. These aviation interests must reach
concensus to convince extended stakeholders that TA
enhances society as a "good neighbor". The TACO lays out a
basis for them to help reach a public consensus regarding the
best use of TA in the NAS.
Aviation Self-Regulation Principle
By tradition the FAA relies on all sectors
of aviation, via its user & industry associations, to
refine & promote best practice of members. Safe
operations & responsible leadership by each sector allows the
FAA to maximize resources & perform oversight with a
The Airborne Wind Energy Industry Association
(AWEIA) undertakes, as part of its formal mission, to perform
the leadership role of self-regulation for AWE in particular, but
also to serve specialized TA as a whole. This TACO is AWEIA's
first step in coordinating member standards for safety
& acting as the industry liason with the FAA & ICAO.
AWEIA will petition the FAA for new Rulemaking following the example of
the Experimental Aircraft Association
(EAA) & FAA together creating the regulatory package
for a new category of Light Sport Aviation. Similarly AWEIA will
work within the ICAO framework to develop a core SARPs.
There are already urgent R&D safety issues AWEIA is
addressing, such as obligatory sharing of safety-critical failure modes
& mishap reporting. AWEIA is just one of several associations
with overlapping interest in TA. AOPA & EAA have strong interests
within the new sectors. The American Kiters Association (AKA) governs
recreational & professional kite operations. The American
Modelers Association (AMA) is responsible for safe hobbyist aviation.
User associations in soaring & other sectors that
commonly perform tethered operations also have stakeholder
oversight roles. Key wind energy
industry standards promoted by AWEA also apply to AWE
TA Excise Taxes & User Fees
The new AWE technology taps airspace as a source of vast energy. M
ajor energy sources all pay excise taxes, with 5% of producer's
selling price typical. Unlike excise taxes on extractive non-renewable
energy sources which eventually run out, renewables generate revenue in
perpetuity. Barriers to
broad AWE societal stakeholder acceptance, like NIMBY
(not-in-my-back-yard) forces, will tend to melt away before a
rich new tax base that more than offsets any negatives. Energy excise taxes often directly offset environmental downsides with mitigation measures. The average
citizen who does not fly or own aircraft still shares
a birthright to the airspace commons. An equitable AWE Excise Tax
can make a huge contribution to basic social welfare & a
new era of sustainable prosperity for all.
Airspace access is by tradition a Public Commons
based on Freedom-of-the-Seas. There is already resistance by
existing aviation stakeholders to allowing privatization of
AirSpace as some venture-capital AWE stakeholders have proposed.
Utility-scale AWE operations can contribute to shared
airspace by paying Excise Taxes on energy
extracted & maybe even special Airspace User Fees. Airspace User Fees is a toxic idea to existing aviation but makes sense for some of the new types of aviation.
The AWE industry can thus earn aviation
stakeholder acceptance by subsidizing common airspace
infrastructure benefiting all. AWE tax revenue can
offset existing FAA costs, relieving the overall Federal budget, pay
for NextGen infrastructure, guarantee liability performance, & fund publicly-shared AWE R & D. The
early industry requires a phase-in period for taxes, so as to not choke
off early investment & to promote initial growth. As
significant mature AWE revenue-base develops, & airspace
becomes widely impacted, the tax base can be tapped. Small-scale
personal AWE operating at low altitudes should be exempted commercial
Like all aviation, TA operations must carry Liability
Insurance proportional to risk. Such insurance is
currently unavailable from traditional providers & a
special TA Liability Fund is needed to jumpstart
liability coverage. Secondary coverage, like Hull Insurance, does not
fall under this recommnedation. A wrongful death these
days can cost some ten million USD. The insurability guaranteed by
an excise endowed fund can ensure that a financially weak AWE
player in a freak-accident (even an unknown
failure-mode) event does not leave victims or families
FARs Category, Class, & Type Certifications for TA
The FAA tasks the AWE Industry (AWEC2010) with
defining the profusion of TA designs & new Types into the
FAA's Aircraft/Airman/Operations Category, Class, & Type
System. As categories naturally grow by adding Classes,
so special TA Classes are proposed to be defined within
current Categories. Note that FARs are sometimes vague,
confused, & contradictory; no totally clean classification
scheme is workable, only patchwork progress. NextGen FARs
will improve classification by a major
overhaul. There is traditional wiggle-room in the
existing system, with many exceptions & options at the discretion
of authorities, including classification under multiple categories
& classes. Aviation is increasingly diverse & some
new branches may become wholly new Categories.
Just like any other aircraft, TA platforms can be
classified by gross-weight & airspeed, by the same physics of
"consequence". Weight & Speed (mass & velocity) are primary
determinants of Class within a Category. In general higher
mass/velocity Classes have Higher Consequence Failure-Modes
& so require proportionally higher standards for
equivalent safety (mortality to flight hours). Stall Speed is a
key safety consideration, the lower the better, with the widest
possible range of operation between max airspeed & stall speed.
Some major Aircraft Categories- aircraft,
rotorcraft, normal, utility, acrobatic, commuter, transport,
manned free balloon, glider, special, restricted, etc. As
an example of how TA Class can apply across
Categories, many given Types can be modified for aerotowing,
with special restrictions accruing. Single/Multi-Engine Classes-
Many TA applications have powered modes that naturally assign them to
an Engine Class within a Category. The trade-off of getting
improved reliability from multi engines is a higher standard
of Pilot training & engineering design required.
Examples of new Classes created- Tethered-Aerobatic,
Tethered-Single-Engine, Tethered-Multi-Engine, Tethered-Normal,
Utility, Sport, Ultralight, Moored-Balloon, Aero-Towed Glider, Tethered
The tether is a significant flying object in itself.
Far-flung tether geometry is a unique TA feature to account for,
but has useful similarity to standard geometry flight
trajectories & operations like skydiving. Electrically Conductive
Tethers require special standards addressing all safety issues.
Aircraft joined by tethers into arrays is an operational
configuration to validate. The proposal is that this method might
greatly enhance safety & reliability.
Some Categories & Classes of aircraft &
operations are interrelated. For example, UAS Aircraft & Flight
Operations are clearly intimately coupled. On the other hand, a UAS
might be operated as a Commercial or Private Aircraft.
Tethered Aircraft (TAC) that operate aerobatically &
incur high G-loadings are Acrobatic Category (limited to 12,500lbs
gross). Tether-Weight counts toward rated gross weight.
Tether-Drag counts against rated L/D. Autonomous Flight of
high-consequence platforms (high mass &/or velocity, especially
around populations) require a proportionately more
cautious rigorous path to validation & certification.
AWECS are generally high-duty UAS & so merit
Utility designation. According to gross weight they can be sorted into
Ultralight, Sport, Normal, Commuter, & Transport Weight &
Operational altitude is a major category criteria. Some
relevant ceilings- 400ft for low mass low speed hobbyist model
aviation. 500ft as a "floor" for general VFR aviation. Class G
airspace, which is low, but variable, with higher
ceilings in remote areas, 2000ft obstruction regulations for mast &
tower certification, 18,000ft as an "absolute" ceiling to avoid
transport aviation operations.
Note: Many current tethered vehicle platforms are
not formally designated as an "aircraft" in the Aircraft
Categories under current FARs, but the FAA reserves the right to
designate them so. Its now clear that the tethered aircraft must
be designated as aircraft so as to be regulated for airworthiness. The
irrefutable logic is that any accepted aircraft can in principle be put
on a tether, which does not negate its character as an aircraft of a
given mass & speed envelope, & even adds to operational hazard.
The many large tethered aircraft under development will have to be Type
Certified in a suitable Category, a Special Class.
Pilot Categories & Training
Proper pilot training & testing is
fundamental to every branch of aviation. All pilots in TA-shared
airspace require awareness of the new conditions. All TA pilots require
basic aeronautical training, plus specialized operational
proficiency. As high-consequence risk emerges, TA Pilots
will require the same high standards of certification as
Sec. 61.31 — Type rating requirements, additional training, and authorization requirements.
Given Aircraft Types operate in diverse roles &
regulations reflect this. Some major Operational Categories that are
explicit or de-facto- , Remoteness, Altitude, Marine Environment,
Unmanned Aviation System, IFR/VFR, Weight & Speed Cats.,
Obstruction, & so on.
Super Density Operations (SDO)
It has been proposed by some developers that AWE can
operate under Obstruction Regs such as govern Antenna Farms,
but such a model is only partial. For example, an
antenna-farm Obstruction is also regulated under mast &
tower structural codes not under the purview of the FAA. Towers do
not have many inherent aviation hazards related to
aircraft airworthiness & a potential to crash far afield.
Therefore a TAC partly regulated as an obstruction still needs to
comply with Airworthyness regs.
Current Norms & Regulations
The FAA's mandate to maintain a safe NAS already covers TA activity.
Certificating airworthiness within current
regs is essential to prevent TA R&D
from presenting a "menace-to-aviation". Most AWE venture
starts have no formal aviation background &
face acculturation along an FAA approved path. Class G
Airspace is the primary realm of current TA R & D.FSDOs
are the current arbiters of allowable experiments, with decentralized
flexibility. AWE R & D can shop around for a "best-fit" FSDO
(generally remote low-traffic NAS regions). Special
Airworthiness Certificate in the Experimental Category is the
certification currently available to civil operators of UAS. NOTAM & COAs allow pioneering AWE R & D to occur.
Obstruction regs, such as apply to antenna
farms, can partly serve for persistent "static" TA operations
under 2000ft AGL.Shielded operations is an option for a TA operator able to identify sites.
Draft FAA s UAS regs call for Pilot-in-Command & Visual Observer crews.
A misconception in the AWE field is that autonomous
operations will permissible in a short time-frame of a year or
two, but the safer bet is that many years must pass before the required
safety & reliability is validated & permitted.
Key Title 14 Parts of the Code of US Federal Regulations (Aeronautics & Space)
PART 101 - MOORED BALLOONS, KITES, UNMANNED ROCKETS AND UNMANNED FREE BALLOONS
Part 77 - OBJECTS AFFECTING NAVIGABLE AIRSPACE
The FAA regulates skydiving activity as"Parachute Operations"
Part 105 (14 CFR 105). Flight operations for skydiving are conducted
under Part 91 "General Operating and Flight Rules" (14 CFR 91).
FAA Advisory Circulars provide additional guidance about operations. A TAConOps circular is a logical step.
Banner-Towing & Glider Aero-Towing regulations inform equivalent operations in other applications.
Recreational NAS use covered by
FAA Advisory Circular (AC) 91-57; generally limits operations to below
400 feet ASL well separated from airports & air
traffic. This is the appropriate place for virtually all current AWE
developers to conduct most experiments without being a "menace to
Three acceptable means of operating UASs
in the NAS: 1) within “restricted” airspace: or under a Special
Airworthiness Certificate (2) Experimental Category or (3)
Certificate of Waiver or Authorization (COA). A COA
authorizes an operator to use defined airspace under specific
provisions unique to the operation. It may require Visual
Flight Rules (VFR) & operation only &/or during daylight.
COAs are issued for a specified time period; one year typical. COAs require coordination with air traffic control & may require a transponder in certain types of airspace.
A UASs inability to
autonomously follow ”sense and avoid” rules means a ground
observer (PIC &/or VO) must maintain visual contact
operating in unrestricted airspace. The VO must also maintain aural vigilence in a quiet enough setting to detect airplane intrusion before visual spotting.
"Sense & avoid" UASs requirement
currently means PIC (Pilot-In-Command) & VO (Visual Observer),
plus dive or kite-kill capability.
Possibility of special IFR Rules
clearances, especially higher operational ceiling during graveyard
shift to help bridge night-time inversion.
TA Operations Notes
Tethered Aviation creates unique operational realities with particular hazards to mitigate.
A tether is a dangerous poorly
visible obstacle when extended almost invisibly across large
distances. Navigation markers are an existing requirement
& will surely long continue to be a good idea.
Separation, Avoidance, Visibility, & Education
(SAVE) is a useful mnemonic for the basic principles of safe TA
operations. S is for passive Separation; the relegation of TA
operations to remote low-traffic airspace; A is for Avoidance; the
effective evasive capability of a TA platform (ie. "kite-killers"). V
for Visibility is the standard for obstruction markings, transponders,
radar-reflectance, etc.. E for Education is the requirement to
appropriately inform & train all pilots operating in proximity to
TA, as well as the special Type-Rating knowledge a TA PIC needs.
Turbines on resonant composite wings can be quite noisy
making the Visual Observer "deaf" to intruding air traffic (Often an
airplane is heard before its seen, helping "sense & avoid".).
Special Risks- Mid-Air Collisions, Breakaway, Tether Dragging, Conductive-Tethers, Security,
TACO/Nextgen Transformation Path
The general iterative-spiral validation process toward NextGen Integration-
TACO Draft focuses mostly on near-to-mid-term AWE R & D.
The forward-looking capabilities referenced
below derive from the NGATS Vision Briefing of 2005
toward the NextGen Airspace CONOPS for 2025. Mature Tethered
Aviation Operations (TAO) shall conform to these standards-
Supervisory Override of Semi-Automated Flight is a bridge technology
NextGen's Moving Constrained Airspace is a capability needed for Tethered Free-Flight development
EVFR rules for relaxed visibility will widen the TA flight envelope & be a bridge to Autonomous IFR .