Section 107.29 Daylight operation.
(a) No person may operate a small unmanned aircraft system during night.
(b) No person may operate a small unmanned aircraft system during periods of civil twilight unless the small unmanned aircraft has lighted anti-collision lighting visible for at least 3 statute miles. The remote pilot in command may reduce the intensity of the anti-collision lighting if he or she determines that, because of operating conditions, it would be in the interest of safety to do so.
(c) For purposes of paragraph (b) of this section, civil twilight refers to the following:
(1) Except for Alaska, a period of time that begins 30 minutes before official sunrise and ends at official sunrise;
(2) Except for Alaska, a period of time that begins at official sunset and ends 30 minutes after official sunset; and
(3) In Alaska, the period of civil twilight as defined in the Air Almanac.
My Commentary on Section 107.29 Daylight operation.
See my article on flying at night for the discussion on the definition of night for Section 1.1 and civil twilight for 107.29.
Daylight Operations. Part 107 prohibits operation of an sUAS at night, which is defined in part 1 as the time between the end of evening civil twilight and the beginning of morning civil twilight, as published in The Air Almanac, converted to local time. In the continental United States (CONUS), evening civil twilight is the period of sunset until 30 minutes after sunset and morning civil twilight is the period of 30 minutes prior to sunrise until sunrise. In Alaska, the definition of civil twilight differs and is described in The Air Almanac. The Air Almanac provides tables which are used to determine sunrise and sunset at various latitudes. These tables can also be downloaded from the Naval Observatory and customized for your location. The link for the Naval Observatory is http://aa.usno.navy.mil/publications/docs/aira.php.
Civil Twilight Operations. When sUAS operations are conducted during civil twilight, the small UA must be equipped with anticollision lights that are capable of being visible for at least 3 sm. However, the remote PIC may reduce the visible distance of the lighting less than 3 sm during a given flight if he or she has determined that it would be in the interest of safety to do so, for example if it impacts his or her night vision. sUAS not operated during civil twilight are not required to be equipped with anti-collision lighting
FAA’s Discussion on Section 107.29 Daylight operation from the Final Small Unmanned Aircraft Rule
Due to the reduced visibility associated with nighttime operations, the NPRM proposed to prohibit the operation of a small UAS outside the hours of official sunrise and sunset. For the reasons discussed below, this rule will maintain the prohibition on nighttime operations but will allow small UAS operations to be conducted during civil twilight if the small unmanned aircraft has lighted anti-collision lighting visible for at least 3 statute miles. The nighttime-operations prohibition in this rule will also be waivable. Approximately 25 commenters generally supported the proposed prohibition on operations outside the hours of official sunrise and sunset. ALPA noted that the prohibition is consistent with the ARC recommendations. The Minneapolis-Saint Paul Metropolitan
Airports Commission (Metropolitan Airports Commission) asserted that nighttime operations introduce a number of visual illusions, and unlike manned-aircraft pilots, small
UAS operators will not be required to complete comprehensive training programs that teach pilots how to deal with these illusions. The City and County of Denver, Colorado noted that allowing operations only in the lightest of conditions will increase the probability of avoidance in the event of a conflict.
Federal Airways provided some conditions and limitations under which they would support nighttime operations of UAS, but ultimately noted that if the goal is to be as least burdensome as possible, limiting operating hours to daylight hours only would eliminate the need for further specification in lighting requirements. The American Association of Airport Executives and Barrick Gold of North America, Inc. concurred with the nighttime operation prohibition, but added that in the future, technological advances may provide the opportunity to allow nighttime operations.
Other commenters objected to the proposed prohibition on nighttime operations. Skycatch, Clayco, AECOM and DPR Construction, commenting jointly, and several individuals, suggested that the proposed prohibition on nighttime operations be entirely eliminated from the final rule. Cherokee Nation Technologies and The Information Technology and Innovation Foundation asserted that nighttime operations can be safer than daytime operations because there is less air traffic and there are fewer people on the ground. EEI and AUVSI suggested that nighttime UAS operations are safer and less disruptive than nighttime manned-aircraft operations such as helicopters circling overhead. Virginia Commonwealth University Honors Students said the proposed ban on nighttime operations ignores the use of other senses, particularly sound, to detect and avoid other aircraft. DJI stated that because manned aircraft operating at night are required to be equipped with lighting, UAS operators would be able to satisfy their see-and-avoid requirements, even when operating at night.
A large number of commenters who opposed the daytime-only restriction of small UAS operations proposed several methods of mitigating hazards. The mitigation strategies were generally related to improving visibility to support see-and-avoid, augmenting seeand-avoid with technology, implementing additional restrictions for operations at night, and requiring additional certification or training. For example, the Airborne Law Enforcement Association, NBAA, and the National Ski Areas Association said nighttime operations of small UAS could be conducted safely if the aircraft is equipped with proper lighting. The National Association of Broadcasters, National Cable & Telecommunications Association and Radio Television Digital News Corporation, commenting jointly, and the Associated General Contractors of America supported nighttime operations in well-lit areas, such as closed sets or sites of sporting events. The Kansas State University UAS Program cited preliminary research that, it argued, indicates that UAS equipped with navigation lights are often easier to see at night than during the day.
Nighttime operations pose a higher safety risk because the reduced visibility makes it more difficult for the person maintaining visual line of sight to see the location of other
aircraft. While the existence of other lighted manned aircraft may be apparent due to their lighting, the distance and movement of small unmanned aircraft relative to the distance and movement of those aircraft is often difficult to judge due to the relative size of the aircraft. In addition, visual autokinesis (the apparent movement of a lighted object) may occur when the person maintaining visual line of sight stares at a single light source for several seconds on a dark night. For this reason, darkness makes it more difficult for that person to perceive reference points that could be used to help understand the position and movement of the lighted manned aircraft, the small unmanned aircraft, or other lighted object.
The lack of reference points at night is problematic for small UAS subject to part 107 because they are not required to have any equipage that would help identify the precise location of the small unmanned aircraft. As such, a remote pilot in command operating under this rule will generally rely on unaided human vision to learn details about the position, attitude, airspeed, and heading of the unmanned aircraft. This ability may become impaired at night due to a lack of reference points because all a remote pilot may see of his or her aircraft (if it is lighted) is a point of light moving somewhere in the air. For example, a lighted small unmanned aircraft flying at night may appear to be close by, but due to a lack of reference points, that aircraft may actually be significantly farther away than the remote pilot perceives. An impairment to the remote pilot’s ability to know the precise testing. Finally, the article concluded by noting that “more analysis is needed.” As a result, the FAA does not
currently have sufficient information to evaluate the research cited in the comment. position, attitude, and altitude of the small unmanned aircraft would significantly increase the risk that the small unmanned aircraft will collide with another aircraft.
In addition to avoiding collision with other aircraft, remote pilots in command must also avoid collision with people on the ground, as well as collision with ground-based structures and obstacles. This is a particular concern for small UAS because they operate at low altitudes. When operating at night, a remote pilot may have difficulty avoiding collision with people or obstacles on the ground which may not be lighted and as a result, may not be visible to the pilot or the visual observer. As such, this rule will not allow small UAS subject to part 107 to operate at night (outside of civil twilight) without a waiver.
The Motion Picture Association of America (MPAA) and several individuals recommended that small UAS operations be permitted between civil dawn and civil dusk. The commenters stated that there is sufficient light during civil twilight to see and avoid ground-based obstacles. One commenter compared UAS to ultralight vehicles, citing precedent in § 103.11(b), which allows ultralight vehicles to be operated during civil twilight, provided the vehicle is equipped with an operating anti-collision light visible for at least 3 statute miles. The Drone User Group Network suggested that with appropriate
lighting, a small UAS would in fact be more visible in low light than during the day, thus enabling the remote pilot to exercise his or her visual-line-of-sight responsibility. Many of the comments cited photography as a type of operation that could be conducted during twilight hours.
Civil twilight is a period of time that, with the exception of Alaska, 84 generally takes place 30 minutes before official sunrise and 30 minutes after official sunset. The
FAA agrees with commenters that operations during civil twilight could be conducted safely under part 107 with additional risk mitigation because the illumination provided
during civil twilight is sufficient for terrestrial objects to be clearly distinguished during clear weather conditions. As a result, many of the safety concerns associated with nighttime operations are mitigated by the lighting that is present during civil twilight. That is why current section 333 exemptions permit twilight UAS operations. Accordingly, this rule will allow a small UAS to be operated during civil twilight.
However, while civil twilight provides more illumination than nighttime, the level of illumination that is provided during civil twilight is less than the illumination provided between sunrise and sunset. To minimize the increased risk of collision associated with reduced lighting and visibility during twilight operations, this rule will require small unmanned aircraft operated during civil twilight to be equipped with anti-collision lights that are visible for at least 3 statute miles.
A remote pilot in command may reduce the intensity of the anti-collision lights if, because of operating conditions, it would be in the interest of safety to do so. For example, the remote pilot in command may reduce the intensity of anti-collision lights to minimize the effects of loss of night vision adaptation. The FAA emphasizes that anti-collision lighting will be required under this rule only for civil twilight operations; a small unmanned aircraft that is flown between sunrise and sunset need not be equipped with anticollision lights.
The FAA acknowledges that current exemptions issued under Public Law 112-95, section 333 allow civil twilight operations without a requirement for anti-collision lighting. However, the section 333 exemptions do not exempt small UAS operations from complying with § 91.209(a), which requires lighted position lights when an aircraft is operated during a period from sunset to sunrise (or, in Alaska, during the period a prominent unlighted object cannot be seen from a distance of 3 statute miles or the sun is more than 6 degrees below the horizon). As such, UAS currently operating under a section 333 exemption have lighting requirements when operating during civil twilight. However, while current section 333 exemptions rely on position lighting, it would
be impractical for this rule to prescribe specifications for position lighting for civil twilight operations because a wider range of small unmanned aircraft will likely operate under part 107. Position lighting may not be appropriate for some of these aircraft. Thus, instead of position lighting, small unmanned aircraft operating under part 107 will be required to have anti-collision lights when operating during civil twilight.
The FAA also notes that meteorological conditions, such as haze, may sometimes reduce visibility during civil twilight operations. Accordingly, the FAA emphasizes that, as discussed in the following section of this preamble, this rule also requires that the minimum flight visibility, as observed from the location of the ground control station, must be no less than 3 statute miles.
Several commenters, including the Nature Conservancy, MPAA, Commonwealth Edison Company, the American Fuel & Petrochemical Manufacturers, and the Newspaper Association of America, suggested that certain types of operations should be exempt from the proposed nighttime prohibition. These operations include: emergency operations, public service operations, hazardous material response, railroad incident management, public utility inspection and repair, pipeline monitoring, thermal roof inspections using infrared technology, conservation-related operations in sparsely populated areas, ski area operations where people and property can be easily avoided, news-reporting, and filming in controlled, well-lit areas. The American Farm Bureau and several other commenters
claimed that certain UAS operations are best conducted at night. These operations include research and humanitarian operations, crop treatments, wildfire fighting, nocturnal wildlife monitoring, infrastructure monitoring, and operations using infrared and thermal imaging cameras. The Property Drone Consortium stated that a daylight-only requirement would restrict the ability of its members to conduct thermal imaging using small UAS.
Commonwealth Edison stated that the proposed restriction to daylight-only operations would constrain the ability to use small UAS to respond to emergencies that occur outside of daylight hours. Similarly, NRECA stated that the restriction to daylight operations would severely impede its members’ ability to respond to electrical grid emergencies caused by weather. Both Commonwealth Edison and NRECA suggested that the final rule include deviation authority to allow nighttime operations if it can be shown that such operations can be conducted safely. Similarly, Boeing, the University of North Dakota’s John D. Odegard School of Aerospace Sciences, and DJI recommended that the proposed nighttime-operation prohibition be amended to allow waivers to be authorized by the Administrator to accommodate time-critical and emergency operations that may need to be conducted at night if those operations can be conducted safely.
The FAA agrees with commenters that there could be benefits to allowing certain small UAS operations at night, such as search and rescue or firefighting operations when those operations are conducted as civil operations. As such, the nighttime-operation prohibition in this rule will be waivable. The FAA will consider granting a certificate of waiver allowing a nighttime small UAS operation if an applicant can demonstrate sufficient mitigation such that operating at night would not reduce the level of safety of the operation. The American Petroleum Institute recommended an exception for Alaska’s North Slope, an area of significant operations for the oil and gas industry. The commenter noted that there are no daylight hours for approximately 3 months of the year in that area. The same safety concerns exist in northern Alaska as they do anywhere in the United States during periods of darkness. However, as discussed previously, this rule will allow small UAS operations to be conducted during civil twilight. This will add significantly greater flexibility to Alaska operations because for the northernmost portions of Alaska, the sun never rises for as many as 64 days a year. By allowing operations to take place during civil twilight, this rule will allow small UAS operations year round, even in Alaska’s North Slope. In addition, as discussed previously, the FAA will consider granting a certificate of waiver for specific nighttime operations if the applicant can demonstrate that operating at night will not reduce the safety of the operation.
Qualcomm, FLIR Systems, the Drone User Group Network, and several individuals supported operations at night utilizing technology such as night-vision cameras to allow the aircraft to be safety piloted. The Association of American Railroads contended that risks associated with nighttime operations could be mitigated by requiring small unmanned aircraft to be equipped with sense-and-avoid technology approved by the FAA. Kapture Digital Media and another commenter asserted that night-vision-enabled FPV cameras are available that would aid in seeing-and-avoiding other aircraft and hazards at night. The South Dakota Department of Agriculture suggested that the FAA prescribe a performance based standard in lieu of daylight-only restrictions, thus allowing for the integration of new risk-mitigating technologies as they are developed and refined. The Colorado Cattlemen’s Association suggested that risks related to low-light and nighttime operations could be mitigated through technological equipage.
For the reasons discussed earlier in this preamble, existing vision-enhancing devices, such as FPV, do not currently provide a field of vision sufficient for the user to safely see and avoid other aircraft. Current sense-and-avoid technology would also insufficiently mitigate the risk associated with flying at night because this technology is still in its early stages of development. As of this writing, there is no sense-and-avoid technology that has been issued an airworthiness certificate. The FAA will keep monitoring this technology as it develops and may incorporate it, as appropriate, into certificates of waiver, future UAS rules, or possible future revisions to part 107.
Several commenters suggested permitting nighttime operations by further segmenting the small UAS category of aircraft by lesser weights or lower operational altitudes. However, even a relatively light small unmanned aircraft could cause a hazard by colliding with another aircraft in the NAS or an object on the ground. As discussed previously, these safety risks are more prevalent at night due to reduced visibility. While low weight could be one mitigation measure that a person could use to support a waiver application, this factor, by itself, would be unlikely to mitigate the additional risk associated with a nighttime small UAS operation.
Embry-Riddle and the Florida Department of Agriculture, Consumer Services’ UAS Working Group (Florida Department of Agriculture) proposed allowing operators possessing additional certification to fly at night. Textron Systems and several individuals recommended additional training for night operations.
As discussed previously, this initial small UAS rulemaking effort is intended to immediately integrate the lowest risk small UAS operations into the NAS. The FAA plans to address higher risk operations and the mitigations necessary to safely conduct those operations, such as the mitigations suggested by the commenters, in future agency actions. The FAA will consider the commenters’ recommendations as part of future rulemaking efforts to integrate higher-risk UAS operations, such as nighttime operations, into the NAS. AUVSI, Prioria Robotics, and a joint submission from Skycatch, Clayco, AECOM, and DPR Construction pointed to Australia and New Zealand as examples of countries where nighttime operations have been safely conducted in areas with established UAS regulations. In keeping with U.S. obligations under the Convention on International Civil Aviation, it is FAA policy to conform to ICAO SARPs to the maximum extent practicable. However, there are currently no ICAO SARPs that correspond to the nighttime-operation provisions of these regulations. Because the integration of UAS into the NAS is an incremental process, the FAA will continue expanding UAS operations to include those that pose greater amounts of risk, utilizing data gleaned from industry research, the UAS test sites, and international UAS operations.
Matternet and the Mercatus Center at George Mason University cited § 101.17, stating that kites and moored balloons operate safely at night, with specific lighting requirements, even though they are not equipped with the kinds of sense-and-avoid technologies likely included in small UAS systems.
As discussed previously, sense-and-avoid technology does not currently provide sufficient mitigation to enable nighttime operations. In addition, while kites and moored balloons operated under part 101 are permitted to operate at night, § 101.15 requires the kite or moored balloon operator to notify the nearest ATC facility of the details of the operation at least 24 hours prior to each operation. Because kites and moored balloons governed by part 101 operate in a fixed location, this ATC notification allows ATC to disseminate details of the operation to other aircraft in the area. Conversely, with some exceptions, small UAS operating under part 107 in Class G airspace will not be required to communicate with ATC prior to or during the operation.
One commenter suggested that small UAS operations be limited to the period between one half hour after official sunrise and one half hour before official sunset, arguing that it is not uncommon for small unmanned aircraft to have low-visibility color schemes. However, it is not necessary to further reduce operations conducted near sunset or sunrise to mitigate the risk of small UAS operations in low light conditions. As discussed previously, low-light conditions provide sufficient lighting to mitigate many of the safety concerns underlying the prohibition on nighttime operations.
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