UNITED STATES OF AMERICA

DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

WASHINGTON, DC 20591

____________________________________

)

In the matter of the petition of )

)

BNSF RAILWAY COMPANY ) Regulatory Docket No. FAA-2014-0704

) Exemption No. 11206A

For an exemption from §§ 61.113(a), )

91.7(a), 91.119(c), 91.121, 91.151(a)(1) )

91.405(a), 91.407(a)(1), 91.409(a)(1) and )

(2), and 91.417(a) and (b) )

____________________________________)

RESPONSE TO FAA’s FOLLOW-UP QUESTIONS

BNSF Railway Company (“BNSF”) hereby responds to a series of follow-up questions 

by the Federal Aviation Administration concerning BNSF’s two recent petitions for an 

amendment to Exemption No. 11206,1 permitting BNSF to conduct certain operations using a 

small unmanned aircraft system (“sUAS”) over BNSF owned or controlled railroad 

infrastructure and operations.

Specifically, in one petition BNSF seeks to amend paragraphs 1, 5, 6, 16, 18 and 20 of 

the exemption (FAA-2014-0704-10); in the other petition, BNSF seeks to amend paragraphs 1, 

29 and 31 of the exemption (FAA-2014-0704-11). Since the FAA’s request addressed portions 

of both petitions, we are providing a single, consolidated response here. BNSF believes the 

suggested amendments, discussed in detail in the petitions and below, will in many instances 

improve, and in no instance degrade, the safety of individuals on the ground and in the air over 

what is achievable under the existing exemption. With over 225 hours of safe UAS flight time 

conducting visual line of sight (VLOS) operations under the existing exemption, BNSF believes 

it has demonstrated a strong safety culture that justifies expansion of the current conditions and 

limitations. 

Improving the safety of rail operations and BNSF staff is a primary driver in BNSF’s 

UAS operations. One of the primary benefits of UAS operations is the safe and efficient 

inspection of infrastructure with a minimum exposure of crew to the track and minimal system 

down time. Traditional inspections of railway infrastructure, including rail, bridges and towers, 

 1 On December 15, 2015 the FAA amended BNSF’s exemption to add additional aircraft and permit 

individuals holding a recreational or sport pilot certificate to serve as PIC. Because of this amendment, the 

exemption is now identified as “Exemption No. 11206A.”
2

are accomplished by having personnel walk, drive, and climb over, under or around the tracks 

and other structures. These traditional inspection methods expose BNSF personnel to risk that 

can be mitigated by UAS operations because they allow inspections from locations other than 

directly on the structure being inspected and can reduce the length of time that an inspector must 

be on or adjacent to the track or other infrastructure. However, because the conditions and 

limitations in the existing exemption, BNSF inspection crews are required to remain on or 

immediately adjacent to the track in instances where BNSF believes it can control for the risk 

that the condition and limitation aims to address. Accordingly, neither employee safety nor 

service efficiency can be maximized. While BNSF does all it can to make the UAS operations as 

safe as possible, there is an irreducible element of risk not only when employees are required to 

work directly on track and rail structures, but also when they are required to be located adjacent 

to the track or in environmental conditions, such as high water, that trigger the need for the 

inspection. 

BNSF believes the amendments are in the public interest because they would allow 

BNSF to better address safety and security risks to track and other infrastructure using sUAS in 

conjunction with or in lieu of more traditional forms of transportation and on-sight inspections. 

Approximately 25% of all rail commerce, including high value and hazardous cargo, move over 

BNSF rail indiscriminately;2 depending on the nature and length of the disruption, any disruption 

in rail operations can cause safety risks to the general public and economic stress to the U.S. 

economy. BNSF further believes that it has amply met the standard for demonstrating an 

amendment to the existing conditions and limitations would not adversely affect safety as 

required by 14 C.F.R. § 11.81(e). 

FAA Request for Additional Information on Conditions and Limitations 5 and 6

BNSF has requested conditions and limitations 5 and 6 be amended to allow for 

operations within either the PIC’s VLOS or a VO’s VLOS. In the instances where it is 

impractical for the PIC to be within VLOS of the unmanned aircraft, BNSF PICs would utilize 

more than one VO, maintaining radio contact with all VOs. The anticipated operations would 

NOT be extended line of sight operations as described in the FAA Pathfinder Focus Area 2 

project. The aircraft would always be within the visual line of sight of either the PIC or a VO.

BNSF appreciates the FAA’s obligation to assure the safety of the NAS as well as people 

and property on the ground. In the context of UAS operations, the FAA has expressed 

significant concern over the safety of individuals and property on the ground. While the UAS 

operations can reduce the risk to BNSF personnel when more traditional forms of inspection can 

be supplemented, BNSF believes it can further reduce risks associated with its current UAS 

operations to its people on the ground if it is permitted to conduct VO-based VLOS operations, 

rather than PIC-based VLOS operations. The use of UAS for track and infrastructure inspection 

 2 Unlike airlines, railroads engaged in common carriage may not refuse a validly offered shipment of cargo, 

including cargo that is classified as hazardous. Such cargo must necessarily be moved along existing tracks and 

cannot readily be diverted from particular population centers or portions of the country. While BNSF’s current UAS 

operations are in remote areas, eventually BNSF intends to expand those operations in to more highly populated 

areas as the technology matures. 
3

increase the safety of track inspectors who are on the track every day, as well as engineering 

personnel tasked with evaluating potential damage to other infrastructure such as bridges. 

However, under the current limitations those inspection personnel remain on the track longer 

than BNSF believes is necessary. This is because currently the aircraft must land once it reaches 

the edge of the PIC’s VLOS and the PIC must then relocate before the aircraft can be further 

used to assist with the inspection, adding time to the overall inspection process. In cases of 

heavy tree cover or hilly terrain, the aircraft may need to be relocated multiple times because the 

PIC’s VLOS is very small (especially when the unmanned aircraft is flown at very low altitudes). 

Allowing “daisy-chaining” using multiple VOs reduces both the amount of time spent by BNSF 

personnel on the track or other infrastructure and disruption to rail operations.

BNSF understands that the FAA has already issued experimental airworthiness 

certificates that allow for either the PIC or the VO to maintain visual contact with the UA. We 

also understand that beyond PIC-based VLOS operations have been conducted at various test 

sites. Since the ability to observe the aircraft is not based on the aircraft’s characteristics, BNSF 

believes the FAA should extend this relief to section 333 exemption holders who can 

demonstrate an ability to fully staff their UAS operations, to follow procedures similar to those 

used at the various test sites and as part of the conditions for an experimental airworthiness 

certificate, and who have the necessary control of the property over which the aircraft will fly to 

mitigate risk to the general public.3

 The FAA can assure that these measures are taken as part of 

any VO-based VLOS by including a condition and limitation that imposes such a requirement on 

the holder of the exemption. BNSF also believes modification of conditions 5 and 6 to allow 

flight beyond the operator’s VLOS as long as the aircraft remains within VLOS of a VO is 

consistent with the implicit recognition in existing condition and limitation 6 that the PIC may 

rely upon a VO to maintain VLOS. 

The FAA has requested BNSF to supply additional information to support its request to 

modify conditions 5 and 6. Specifically, the FAA notes that “the petition lacks a justification to 

guarantee safe operations. BNSF is required to provide [a] safety case to demonstrate acceptable 

risk levels of operating in the NAS.”

As an initial matter, BNSF believes it is helpful to explain why any risk to the NAS 

attributable to its operations is negligible absent any additional measures on BNSF’s part. 

BNSF’s UAS operations are conducted over BNSF property that is in remote areas, largely in the 

west and southwest, and distant from significant population centers. As such, much of the 

airspace at higher altitudes is designated by the FAA as class G airspace because the level of 

traffic does not justify a higher designation. The existing altitude limitation in BNSF’s 

exemption already creates a natural buffer between the unmanned aircraft and the rare manned 

 3 Well-established companies with significant infrastructure assets are particularly (and perhaps uniquely) 

well-suited to being able to meet these conditions. First, these companies are highly regulated by other federal 

agencies. Accordingly, they have already adopted a robust safety culture. Second, the cost associated with 

maintaining the infrastructure means that the companies necessarily must exercise care in conducting UAS 

operations because the cost associated with further damaging the infrastructure or disrupting operations is 

potentially significant. Finally, they are the most likely to have control over a sufficient amount of land to justify 

daisy-chaining while still remaining over their own property. 
4

aircraft likely to be in the area. Since BNSF can only conducts operations at altitudes of 400 ft. 

AGL or less, BNSF submits there is minimal risk to other aircraft. 

However, BNSF does not rely solely on the natural airspace constraints associated with 

the geographical aspects of its operations and has voluntarily adopted several safety measures 

that further mitigate the already negligible risk to the NAS. BNSF actively engages in a proactive educational campaign prior to each UAS operation. First, BNSF files a NOTAM request 

for each operation. Since pilots of all aircraft are required by regulation to review all applicable 

NOTAMs prior to flight, this mitigation should be sufficient to alert pilots of traditional aircraft 

of any BNSF UAS operations along their intended flight path. In addition, BNSF has actively 

engaged the communities proximate to planned operations by holding information seminars. 

BNSF believes this outreach can reach those individuals who, for whatever reason, fail to check 

for applicable NOTAMs or who have not decided on a specific flight plan because they are 

flying VFR. Finally, BNSF has installed high power LED navigational lights and/or strobe lights 

on its aircraft with AR-180 lights to improve the aircraft’s visibility.4

 In field tests conducted 

outside of the United States, BNSF has reported excellent visibility at distances of over 8,000 

feet, at altitudes between 100 and 400 ft. AGL, and in conditions ranging from clear, to haze to 

mist.

The sUAS used by BNSF provide the PIC with both a first person view (FPV) from the 

unmanned aircraft and telemetry data. These data enable the PIC to accurately access the speed, 

location and orientation of the unmanned aircraft, as well as the status of critical systems such as 

battery capacity and command-and-control link strength. This equipment supplements the PIC’s 

ability to evaluate the location of the unmanned aircraft and its environment beyond a purely 

visual assessment.

In addition to these community outreach and equipage measures, BNSF’s internal 

processes and training will ensure safe operations. The number of VOs appropriate for a 

particular operation is based on flight duration, equipment, local terrain and weather. Training 

will be provided to all PICs and VOs engaged in daisy-chain operations to inform how these 

conditions may impact both the ability to track the unmanned aircraft, as well as to maintain 

communication between the PIC and the VOs. Prior to each operation, the PIC will determine 

the appropriate number and location of VOs in accordance with BNSF procedures to ensure the 

VOs are strategically situated. If the PIC determines that communications are weak or 

interrupted at anytime during the flight, the aircraft will be placed in hover mode or landed until 

communications are reestablished. Likewise, using the monitoring equipment installed on the 

unmanned aircraft the PIC can use all data at his disposal, including the information relayed by 

the VOs, to assess when the flight should be discontinued due to systems issues, to take 

appropriate action to avoid any other aircraft, or to terminate the flight by landing the aircraft on 

BNSF property. The boundary for aircraft operation will be defined by the extent of the radio 

communication, the FPV video link, and the command-and-control link for a single command 

 4 The output of the top mounted white LED strobe, which BNSF believes would be the most critical to 

aircraft flying above 500 ft AGL is 170 lumen. The output of the red and white LEDs mounted on the end of the 

rotor arms is 2.5 lumen, and the output of the green LEDs mounted on the end of the rotor arms is 4.5 lumen. 
5

station. From the perspective of PIC control and situational awareness, the operation is 

essentially similar to a PIC-based VLOS operation conducted by a PIC and a single VO. 

FAA Request for Additional Information on Condition and Limitation 20 

One of the most critical times BNSF needs to conduct aerial inspections is during 

inclement weather, when there may be possible roadway, ballast or track damage that could 

cause a derailment. The Federal Railroad Administration requires certain inspections depending 

on the amount of rain, snow, heat or cold impacting the track. Severe weather events like the 

flash flooding that took place in Texas and Oklahoma in the fall of 2015 also require inspections 

to ensure the track is safe for train movement. In most cases these inspections are accomplished 

by inspectors walking the track or riding on a small truck. These types of inspections are 

extremely risky because of the existing weather and ground conditions. When a derailment or 

service interruption does occur, a UAS team is immediately transported to the site. Once on-site, 

the UAS team provides assistance to the inspectors and the NTSB, if present, to determine the 

cause of the accident or incident and initiate hazard mitigations. This is a critical time for 

addressing safety and environmental concerns that can be mitigated by allowing all weather 

VLOS UAS operations. Current exemption limitations do not allow UAS operations during less 

than ideal meteorological conditions. Accordingly, BNSF has offered two options for the FAA’s 

consideration. 

First, BNSF requested that the limitation be revised to state that VLOS operations are 

permissible when the weather requires traditional aircraft operate under instrument flight rules 

(IFR). BNSF did not assert that it would conduct IFR operations. Rather, its point was that 

since VFR operations in the area would be precluded, there would be an extremely low risk of 

any interaction between the unmanned aircraft and any manned aircraft. 

 

Alternatively, BNSF suggested the FAA apply the VFR limits in 14 C.F.R. §91.155 for 

class G airspace. Condition and limitation 4 already effectively limits UAS operations to class G 

airspace. Given the exceptionally low altitudes at which the unmanned aircraft are operated, 

BNSF continues to believe there is simply no need to impose visibility conditions on the VO that 

are more stringent than what is required for traditional aircraft in class G airspace. Indeed, 

rotorcraft unmanned aircraft are arguably entitled to the exception in §91.115(b)(1) that requires 

helicopters only remain clear of clouds.

In reviewing BNSF’s request, the FAA requested a safety analysis that identifies hazards, 

risk categories and other necessary mitigation to ensure safe operations in the NAS. The FAA 

further noted that upon receipt of the safety analysis its air traffic organization would convene a 

Safety Risk Management Panel (SRMP) to assess that risk. 

BNSF continues to believe that the natural separation between unmanned aircraft flying 

below 400 ft. AGL and manned aircraft flying IFR, combined with the countermeasures 

described in our response to FAA’s question about modification of conditions and limitations 5 

and 6, does not increase risk to the NAS and would allow UAS operations during critical times 

of weather-related risk to rail operations. In addition, the PIC is already required to conduct a 

pre-flight assessment and would have to determine that the unmanned aircraft could be flown in 
6

those conditions safely. However, BNSF also appreciates the FAA’s concern with BNSF 

conducting UAS operations under IFR conditions, even though BNSF always intended to operate 

the unmanned aircraft under VFR and within VLOS in these conditions. Given the FAA’s 

concerns, and the length of time required to complete an SRMP assessment, BNSF has 

determined that it can continue to address the weather-related risk to rail operations until the 

FAA gains greater confidence with airspace integration (or in this case segregation). 

The FAA has raised no follow-up questions or concerns with BNSF’s suggested 

alternative that condition and limitation 20 be amended to permit operations within the 

parameters set by §91.155 for class G airspace rather than the parameters for class E airspace, 

which is what condition and limitation 20 currently requires. BNSF believes that the mitigation 

measures described above in connection with conditions and limitations 5 and 6 more than 

adequately address any residual risk to other aircraft. Risk to people and property on the ground 

is already addressed by limiting operations to BNSF property and rights of way. 

FAA Request for Additional Information on Condition and Limitation 31

BNSF has requested condition and limitation 31 be amended to delete the references to 

nonparticipating vehicles. While many of BNSF’s assets are located more than 500 feet from 

public roadways, that is not always the case. It is simply impractical to seek the permission of 

people driving on public roads along the track or other infrastructure being inspected. BNSF 

notes that all but one of the unmanned aircraft it currently uses qualify as helicopters under the 

definition in 14 C.F.R. §1.1. Section 91.119(d) specifies that helicopters may be operated at less 

than the minimums prescribed in paragraphs (b) or (c) of that section. It is those minimums that 

establish the minimum distance between the aircraft and nonparticipating persons, vessels, 

vehicles or structures. Thus, in the case of traditional (and much larger) helicopters, the FAA 

imposes no minimum altitude or stand-off distances at all. 

The FAA has determined that BNSF must provide a safety case to justify operations 

within 500 feet of non-participating persons.

BNSF appreciates the FAA’s concern over the safety of the uninvolved public. However, 

seeking an individual’s permission to operate within 500 feet does nothing to address those 

safety concerns. As such, BNSF submits that the FAA reconsider its position on an individual’s 

acceptance of risk and focus instead on the actual risk posed by the unmanned aircraft to the 

uninvolved public travelling on public roads. Because BNSF is only conducting operations in 

remote areas of the country, there are relatively few public roads in the immediate vicinity of 

BNSF tracks and other infrastructure. BNSF has noted anecdotally that among the roads that are 

there, they are not heavily trafficked. As such, BNSF asserts that the risk to uninvolved 

members of the public (who also happen to be enclosed within a vehicle that structurally meets 

the terms set forth in condition and limitation 31(a)) is minimal. 

BNSF believes it is important to distinguish between two types of roadways: those that 

traverse the track at a railroad crossing and those that run roughly adjacent to the track for some 

period of time. For public roadways traversing the track, there is no practical way to address risk 

without ceasing all operations near the railroad crossing. Since the length of time required to 
7

traverse the track can be measured in seconds, BNSF believes any risk can be mitigated by 

having the VO scan the public roads within VLOS and notify the PIC of any vehicle traffic that 

will need to cross the track.5

 In that way the PIC can conduct the UAS operation so that the 

unmanned aircraft is at an appropriate stand-off distance from the railroad crossing when the 

driver crosses the track. Operations along public roads that run adjacent to the track are arguably 

more problematic because the exposure time, while still minimal, is potentially greater. Noting 

the FAA’s concern, BNSF is amenable to implementing procedures that require the PIC to 

conduct a site evaluation of the area to be surveyed before any operation commences. Based on 

this survey, the PIC will assess the distance between the track and the road and, using the flight 

planning tool, will determine the need for a geo-fence to protect the roadway. BNSF has 

determined that it can set the geo-fence function on its unmanned aircraft to operate the aircraft 

at least 100 feet from the public roadway. In the instance of public roadways close to the track, 

this means BNSF will need to limit unmanned aircraft operations to directly above the track. 

UAS operations along roadways adjacent to and closer than 100 feet of the tracks would not be 

permitted. Such an approach significantly impairs BNSF’s ability to conduct UAS safety 

inspection operations over much of its track because several public roadways are within 100 feet 

of the track centerline. However, it also commensurately reduces the exposure level to the 

uninvolved public. 

 5 BNSF had originally offered to provide a designated VO whose sole task would be to monitor the public 

roads. Upon further reflection, given the minimal level of both aircraft and road traffic in the areas where BNSF is 

conducting its operations, BNSF believes a VO should be able to perform both functions, particularly as the VO 

will have both a visual and audio warning of any approaching aircraft.