Project No. OH2015

October 29, 2015

3234 Alta Lane, Lafayette, CA 94549  925-369-2505  www.graygeotech.com

U.S. Department of Transportation

Docket Management System

1200 New Jersey Ave., SE

Washington, DC 20590

Small Unmanned Aircraft Systems

Section 333 Petition for Exemption of Specific Rules of Title 14 CFR

Dear Sir or Madam,

This letter serves as our petition for exemption for certain regulations (listed below) of Title 14 of the Code 

of Federal Regulations (14 CFR) pursuant to Section 333 of the FAA Modernization and Reform Act of 

2012. We request these exemptions to allow Gray Geotech to have the opportunity to make use of 

commercial operation of small unmanned aerial systems (UAS) for aerial data collection. It is our opinion 

that the following list of operational regulations will result in a burden for operation of a small UAS, and that 

we can provide a level of safety at least equal to that provided by the rules, and our request is in the public 

interest.

Specific regulations from which relief is requested: 

• 14 CFR Part 21, Subpart H; Certification procedures for products and parts, Airworthiness Certificates

• 14 CFR § 45.23(a); Display of marks; general

• 14 CFR § 61.113(a); Private pilot privileges and limitations: Pilot in command

• 14 CFR § 91.9; Civil aircraft flight manual

• 14 CFR § 91.119(c); Minimum safe altitudes

• 14 CFR § 91.121; Altimeter settings

• 14 CFR § 91.151(a)(1); Fuel requirements for flights in VFR conditions

• 14 CFR § 91.405(a); Maintenance required

• 14 CFR § 91.407(a)(1); Operation after maintenance

• 14 CFR § 91.409(a)(1)&(2); Inspections

• 14 CFR § 91.417(a)&(b); Inspections

This petition has been prepared following the public guidance offered by the FAA, and our proposed UAS 

operations outlined in this petition are similar in all material respects to relief previously granted by the FAA 

in Grant of Exception Nos. 11062, 11109, 11112, and 11213. It is our opinion the reasons stated by the 

FAA in granting the exemptions listed above also apply to this petition.
Small Unmanned Aircraft Systems

Section 333 Petition for Exemption of Specific Rules of Title 14 CFR

OH2015 29/10/15 Rev 0.1 2

1. REGARDING THE PROPOSED UNMANNED AIRCRAFT SYSTEM

Design and Characteristics of Proposed UAS

We intend to use a Tarot FY650 quadcopter with the 3D Robotics Pixhawk flight controller. The size, 

operation, and capability is equal to the 3DR X-8. Specifically, the proposed UAS is a small battery powered 

quadcopter with a maximum weight of 7.7 pounds, a flight time of up to 25 minutes, and a maximum capable 

flight speed of approximately 50 knots. The proposed UAS is radio controlled via a 2.4 GHz radio, with two 

redundant radio telemetry links (one on the 2.4 GHz system and one on a separate 933 MHz radio)

providing flight information such as speed, altitude, heading, location, remaining battery, GPS signal 

strength, radio control signal strength (and more). This information is periodically monitored by the pilot 

during operation while maintaining visual contact of the UAS in a method similar to scanning the instrument 

panel of traditional aircraft. Both telemetry systems include audible alerts/warnings for critical errors, such 

as GPS signal strength and remaining battery. The on-board flight controller has a programmable geofence to limit the area and altitude of operation. In the event of a loss of radio communications or its loss of 

a valid GPS lock, the UAS has the capability to return to the launch location and/or land at a point within 

the geofenced area.

Details regarding the UAS operation manual, hardware and FCC radio frequency compliance are attached 

as Appendix 1.

Pre-Flight Inspections, Maintenance, and Repair 

Prior to each flight, we will conduct a pre-flight inspection to determine the UAS is in a condition for safe 

flight. The pre-flight inspection includes a check for potential discrepancies (such as inoperable 

components, items, or equipment). If the inspection reveals a condition that affects the safe operation of 

the UAS, we will not take off until the necessary maintenance has been performed and the UAS is found to 

be in a condition for safe flight.

Our preflight and maintenance checklist are attached as Appendix 2

Proposed Flight Operation

Flights will be performed in accordance with the limits stated in the applicable Certificate of Waiver or 

Authorization (COA) issued by the Air Traffic Organization (ATO). Flights will not be conducted closer than 

5 nautical miles of an airport reference point (ARP) as denoted in the current FAA Airport/Facility Directory

or as shown on FAA-published aeronautical charts. All flights will be in day visual meteorological conditions 

(VMC) conditions and within visual line of sight of the pilot in command (PIC). Flights will be operated at a 

lateral distance of at least 500 feet from any persons not associated with the UAS operation, and the aircraft 

will only operate over property with the permission of the owner or authorized agent. 

Typical operation will involve a flight speed of 10 to 15 knots with a flight altitude at 100 to 150 feet AGL, 

and in no case greater than 400 feet AGL (or as limited by the COA). The proposed UAS uses both a 

barometric altimeter and a GPS to measure the flight altitude. Prior to each flight the barometric and GPS 

altimeters are calibrated to provide an altitude relative to the takeoff field elevation, and the planned flight 

altitude will be compared to the height of the ground surface over the planned flight path using digital terrain 

maps. Failsafes will be programmed and used to return the UAS to the launch point or land the UAS within 

the area of operation in case of lost communications, lost GPS position lock, or low battery reserve. The 

UAS will remain clear and give way to all manned aviation operations and activities at all times.
Small Unmanned Aircraft Systems

Section 333 Petition for Exemption of Specific Rules of Title 14 CFR

OH2015 29/10/15 Rev 0.1 3

2. REGARDING THE UAS PILOT IN COMMAND (PIC)

All flights will be conducted by a PIC holding a FAA issued private pilot certificate and a current FAA airman 

medical certificate. The PIC will have the ability to safely operate the UAS, including evasive and emergency 

maneuvers and maintaining appropriate distances from persons, vessels, vehicles and structures.

3. EXEMPTION REQUEST FOR SPECIFIC 14 CFR SECTIONS AND DISCUSSION 

OF EQUIVALENT LEVEL OF SAFETY

14 CFR Part 21, Subpart H; Certification procedures for products and parts, Airworthiness Certificates

In reference to Grant of Exemption No. 11062, Docket No. FAA 2014-0352, we understand the FAA has 

stated that no exemption is needed from this section if a finding is made under the Reform Act that the UAS 

selected provides an equivalent level of safety when compared to aircraft normally used for the same 

application. 

Our proposed UAS weight is less than 7.7 pounds fully loaded, will not carry pilot/passengers, carries no 

flammable liquid fuels, and will be flown within a relatively small and secured area. As such, the proposed 

UAS operating without the restrictions and conditions of 14 CFR Part 21, Subpart H will be at least as safe 

as, or safer than, conventional rotorcraft or fixed wing aircraft operating with an airworthiness certificate.

14 CFR § 45.23(a); Display of marks; general

We request relief from Part 45.23(a) requiring markings on certain sections of the aircraft and markings of 

a certain size.

We will mark the UAS with the intent to readily the identify the UAS owner in case of an incident and should 

enforcement of flight regulations be required. The markings will include a serial number, registered in 

accordance with 14 CFR part 47, and have identification (N−Number) markings in accordance with 14 CFR 

part 45, Subpart C. Markings will be as large as practicable.

14 CFR § 61.113 (a); Private pilot privileges and limitations: Pilot in command

Sections 61.113(a) limit private pilots to non-commercial operations. Because the UAS will not carry a pilot

or passengers, flammable fuel and is of significantly smaller proportions (weight and speed) compared to 

manned aircraft, it is our opinion the risks associated with the operation of a small UAS is also significantly 

diminished such that the proposed operations can achieve the equivalent level of safety by requiring the 

PIC to have a private pilot’s license rather than a commercial pilot’s license. 

14 CFR § 91.9(b)(2); Civil aircraft flight manual, marking, and placard requirements.

The UAS, given its size and configuration has no ability or place to carry a flight manual onboard the aircraft. 

The equivalent level of safety will be maintained by keeping the flight manual at the ground control point 

where the pilot flying the UAS will have immediate access to it.

14 CFR § 91.119(c); Minimum safe altitudes

It is our understanding that the minimum safe altitudes outlined in this section are to minimize hazards to 

persons of property on the surface in the event of a loss of power or other mechanical problem, and are 

based in part on the time required to select the most suitable emergency landing area for manned aircraft 

of significantly larger proportions. 
Small Unmanned Aircraft Systems

Section 333 Petition for Exemption of Specific Rules of Title 14 CFR

OH2015 29/10/15 Rev 0.1 4

However, the operational altitude of small UAS will limited to less than 400 feet AGL. In order to provide an 

equivalent level of safety in the event of low power or mechanical failure, all flight operations will be 

conducted at least 500 feet away from all nonparticipating persons, vessels and vehicles. Alternatively,

barriers or structures will be used to sufficiently protect nonparticipating persons from the UAS and/or debris 

in the event of an accident.

Therefore, we maintain that due to the small size of the UAS, the hazard to persons, vehicles and structures 

is minimal compared to manned aircraft, which should be considered in granting the exemption.

14 CFR § 91.121; Altimeter settings

The UAS proposed uses both barometric pressure sensors and GPS to determine an altitude relative to 

the take-off field elevation, but does not have the ability to use atmospheric pressure reported by weather 

stations to make adjustments to the indicated altitude while inflight. Based on the relatively short flight time 

(less than 25 minutes) and small area of operations, it is our opinion that the altimeter settings required by 

this rule are not practical or required for small UAS. To provide an equivalent level of safety we propose to 

use the GPS and barometric sensor to measure an altitude relative to the take-off field elevation. This 

relative altitude will be reset prior to each flight, to account for changes in atmospheric pressure with time 

or weather. 

We will compare this relative altitude to the ground surface elevation over the planned flight path using 

digital elevation maps (DEM) to ensure the altitude above the ground level does not exceed the maximum 

authorized flight altitude. 

14 CFR § 91.151(a)(1); Fuel requirements for flights in VFR conditions

We believe the intent of this regulation is to prevent a pilot of a manned aircraft from commencing a flight 

without properly planning the flight as required by § 91.103, and the 30 minute VFR fuel reserve is specified 

to allow a margin of safety in case of slower travel time to the planned destination or delays to landing within 

the traffic pattern of an airport. The proposed UAS is battery powered with a maximum flight time of up to 

25 minutes, such that it is not possible to conduct flight operations while still maintaining a 30 minute 

reserve.

The proposed small UAS will be limited to a relatively small and controlled area of operation, and will not 

operate in long distance or cross-country flights. The PIC will ensure that before each flight, there is enough 

available power for the UAS to conduct the intended operation and to operate with at least 25% reserve 

battery power still available. The UAS telemetry system allows for monitoring of the battery level during the 

flight, and a failsafe available to provide return to home or landing function in case the battery voltage drops 

below the reserve level. It is our opinion that this will provide an equivalent level of safety considering the 

size and type of operation for the proposed small UAS.

14 CFR § 91.405(a), 91.407(a)(1), 91.409(a)(1)&(2), 91.417(a)&(b); 

These sections require that maintenance of aircraft, airframe, aircraft engine, propeller, or component parts 

are performed by certified aircraft mechanics and repairmen as authorized by 14 CFR Part 43. Due to the 

size, construction, and simplicity of the small UAS, it is our opinion that it is not practical to limit maintenance 

and repairs to be performed by certified aircraft mechanics and repairmen. 
Small Unmanned Aircraft Systems

Section 333 Petition for Exemption of Specific Rules of Title 14 CFR

OH2015 29/10/15 Rev 0.1 5

We propose to provide an equivalent level of safety by performing maintenance, overhaul, replacement, 

inspection for the aircraft and aircraft components in accordance with the manufacturer’s recommendations, 

and as outlined in the operation manual and preflight checklists attached to this letter. If the UAS has 

undergone maintenance or alterations that affect the operation or flight characteristics, (e.g., replacement 

of a flight critical component), we will perform a functional test flight prior to conducting further operations.

4. PUBLIC INTEREST

We intend to use small UAS to survey land surface features and map geologic hazards. The use of UAS 

allows for mapping of terrain that is difficult or unsafe to survey by traditional land based methods. In 

addition, UAS mapping methods are cost efficient and allow for aerial imaging and data collection of smaller 

sites where the expense of traditional aerial mapping is not warranted.

We believe this petition provides adequate justification for the grant of the requested exemptions allowing 

commercial operation of small UAS for commercial aerial, however, please contact us if you need additional 

information to support the requested exemptions.

Sincerely,

Joe Gray, PE

Geotechnical Engineer

Attachments: Appendix 1 – Operation Manual and Hardware Specifications 

Appendix 2 – Planning, Preflight and Flight Checklist