[Federal Register Volume 81, Number 247 (Friday, December 23, 2016)]
[Proposed Rules]
[Pages 94277-94281]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2016-30910]



Federal Aviation Administration

14 CFR Part 91

[Docket No. FAA-2015-2147; Notice No. 15-05]
RIN 2120-AK51

Transponder Requirement for Gliders; Withdrawal

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Advance notice of proposed rulemaking (ANPRM); withdrawal.


SUMMARY: The FAA is withdrawing a previously published advance notice 
of proposed rulemaking that sought public comment from interested 
persons involving glider operations in the National Airspace System. 
The action responded to recommendations from members of Congress and 
the National Transportation Safety Board and was intended to gather 
information to determine whether the current glider exception from 
transponder equipage and use provides the appropriate level of safety 
in the National Airspace System. The FAA is withdrawing that action 
because the limited safety benefit gained does not justify the high 
cost of equipage.

DATES: This action becomes effective December 23, 2016.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning 
this action, contact Patrick J. Moorman, Airspace Regulations Team, 
AJV-113, Federal Aviation Administration, 800 Independence Avenue SW., 
Washington, DC 20591; telephone (202) 267-8783; email: 
[email protected].



    On August 28, 2006, a Hawker 800XP aircraft \1\ and a Schleicher 
ASW27-18 glider were involved in a non-fatal midair collision near 
Reno, Nevada. The collision occurred in flight about 42 nautical miles 
(NM) south-southeast of the Reno-Tahoe International Airport (RNO), at 
an altitude of about 16,000 feet (ft.) above mean sea level (MSL), and 
in an area where gliders are excepted from the transponder equipment 
requirements in Title 14, section 91.215(b), of the Code of Federal 
Regulations (14 CFR).\2\ The glider was equipped with a transponder, 
but the transponder was not turned on at the time of the accident.

    \1\ The Hawker 800XP aircraft was equipped with a Traffic Alert 
and Collision Avoidance System (TCAS). TCAS is a family of airborne 
devices that function independently of the ground-based air traffic 
control (ATC) system, and provide collision avoidance protection for 
a broad spectrum of aircraft types. All TCAS systems provide some 
degree of collision threat alerting, and a traffic display.
    \2\ The exceptions to the rule allow aircraft that were 
originally certificated without an engine-driven electrical system, 
such as balloons and gliders, to be operated in the following areas 
without a transponder: within a 30 nautical mile radius (NMR) of the 
36 listed airports listed in Appendix D to part 91 (Mode C veil), 
provided aircraft remain outside the Class A, B, or C airspace and 
are below the ceiling of the airspace designated for the Class B or 
C airport, or 10,000 feet MSL, whichever is lower; above 10,000 feet 
MSL; and in the airspace from the surface to 10,000 feet MSL within 
a 10 NMR of any airport listed in appendix D, excluding the airspace 
below 1,200 feet outside of the lateral boundaries of the surface 
area of the airspace designated for that airport.

    On March 31, 2008, the National Transportation Safety Board (NTSB) 
provided safety recommendations to the FAA resulting from an 
investigation of the accident.\3\ The findings of the accident 
investigation address the limitations of the see-and-avoid concept in 
preventing midair collisions and, more specifically, the benefits of 
using transponders in gliders for collision avoidance. The NTSB 
recommended that the FAA remove the glider exceptions pertaining to the 
transponder equipment and use requirements, finding that ``transponders 
are critical to alerting pilots and controllers to the presence of 
nearby traffic so that collisions can be avoided.''

    \3\ A-08-10 through 13, Safety Recommendations. National 
Transportation Safety Board, Washington, DC 20594, March 31, 2008. A 
copy of this letter has been placed in the docket. 
www.regulations.gov docket FAA-2005-2147. Note: while NTSB used the 
term ``exemption'' the correct term as it relates to this airspace 
is ``excepted.''

    On June 16, 2015, the FAA published an Advance Notice of Proposed 
Rulemaking (ANPRM) to respond to recommendations from two members of 
Congress \4\ and the NTSB. 80 FR 34346. The ANPRM requested comments on 
a proposed rulemaking that would require gliders operating in the 
National Airspace System (NAS) to be equipped with transponders. The 
FAA did not propose specific regulatory changes but rather sought 
public comment on the use of transponders in gliders operating within 
the excepted areas of Sec.  91.215. The ANPRM also sought input on more 
recent alternatives to glider equipage including the use of Traffic 
Awareness Beacon System (TABS) \5\ and Automatic Dependent Surveillance 
Broadcast (ADS-B) Out equipment.\6\ The FAA asked for comments from the 
public and industry to aid in the development of a proposed rule and 
the analysis of its economic impact.

    \4\ The FAA received letters from Senator Harry Reid (D-NV) and 
Representative Mark E. Amodei (R-NV); Letters are posted to the 
docket at www.regulations.gov, docket no. FAA-2015-2147.
    \5\ TABS is a surveillance system derived from existing 
transponder and ADS-B requirements. It was developed to increase 
safety by providing a standard for a low cost surveillance solution 
for aircraft excepted from Sec. Sec.  91.215 and 91.225. An aircraft 
equipped with TABS is visible to other aircraft equipped with 
collision avoidance systems such as Traffic Advisory System (TAS), 
Traffic Alert and Collision Avoidance System (TCAS) I, TCAS-II, and 
ADS-B In. However, a TABS-equipped aircraft is not displayed to 
controllers. The FAA published Technical Standard Order (TSO)-C199, 
the standard for TABS, on October 10, 2014.
    \6\ ADS-B is a satellite-based surveillance system that uses 
Global Positioning System (GPS) technology to determine an 
aircraft's location, airspeed, and other data, and broadcasts that 
information to a network of ground stations, which relays the data 
to air traffic control displays, and to nearby aircraft equipped to 
receive the data via ADS-B In.

Overview of Withdrawal

    Based on the information gathered from the ANPRM and a review of 
the current operating environment, the FAA finds that it does not have 
sufficient basis to move forward with rulemaking at this time. While 
the FAA has determined it is not warranted to move forward with a 
proposal to remove the glider exception in Sec.  91.215, the FAA will 
continue to work with local glider communities to increase safety 
awareness. The FAA will also continue to consider surveillance system 
alternatives and to work with interested persons to mitigate the risk 
of aircraft collision with gliders. Further, the FAA recommends that 
all glider aircraft owners equip their gliders with a transponder 
meeting regulatory requirements, a rule-compliant ADS-B Out system, or 
a TABS device.

Comment Summary

    The FAA received 231comments in response to its ANPRM. Of the 231 
comments received, approximately 18 organizations and 213 individual or 
anonymous commenters responded. Approximately 161 comments were 
unfavorable (adverse), 52 comments were favorable, and 18 comments were

[[Page 94278]]

neutral. Of the 18 organizations that commented, 14 responded 
unfavorably (adverse), 2 favorably, and 2 were neutral. Three comments 
received after the comment period closed were also considered.
    The following organizations responded: Soaring Society of America 
(SSA), Aircraft Owners and Pilots Association (AOPA), Vintage Sailplane 
Association (VSA), Experimental Aircraft Association (EAA), Civil Air 
Patrol (CAP), National Transportation Safety Board (NTSB), American 
Association for Justice (AAJ), and approximately 11 local soaring clubs 
or groups. Individual and anonymous commenters were representative of 
all pilot types: glider, general aviation (GA), airline and military, 
many commenters holding multiple ratings, with glider and general 
aviation pilots representing the majority.
    Individual and anonymous commenters in favor of removing the 
transponder exception were primarily concerned about safety, some 
relaying personal experiences not accompanied by supporting 
documentation, such as a near mid-air collision (NMAC) report.\7\ 
Several commenters recommended the FAA consider alternatives to 
transponder equipage, including ADS-B,TABS, or FLARM.\8\

    \7\ An NMAC is an incident associated with the operation of an 
aircraft in which a possibility of a collision occurs as a result of 
proximity of less than 500 feet to another aircraft, or a report is 
received from flightcrew members stating that a collision hazard 
existed between two or more aircraft. A report does not necessarily 
involve the violation of regulations or error by the air traffic 
control system, nor does it necessarily represent an unsafe 
condition. The fact that flightcrew members initiate NMAC reports 
raises two important issues. First, to some degree the data likely 
will be subjective. This necessitates that considerable caution be 
exercised when evaluating individual NMAC reports. Second, it is 
most likely the number of NMAC reports filed will not represent the 
totality of such events.
    \8\ FLARM is an electronic system designed to alert pilots of 
potential collisions between aircraft. FLARM is approved by the 
European Aviation Safety Agency for fixed installation in certified 
aircraft. Aircraft equipped with FLARM (including a variant known as 
PowerFLARM that can receive transponder and ADS-B signals from other 
aircraft) are visible only to other FLARM-equipped aircraft. There 
is no FAA TSO for FLARM because FLARM uses proprietary technology 
rather than industry consensus standards.

    All comments are available for viewing in the rulemaking docket 
(FAA-2015-2147). To view comments, go to http://www.regulations.gov and 
insert the docket number.

Discussion of Comments

1. Safety Benefit of Transponders

    Of the approximately 161 unfavorable (adverse) comments received, 
many addressed the high cost of transponder equipage and the limited 
safety benefit by requiring such equipage.
    During the ANPRM process, the FAA also reviewed glider midair and 
NMAC reports at the local and national level. After further analysis of 
safety related statistics, the FAA found that nationally, from August 
2005 through August 2015, the Aviation Safety Reporting System (ASRS) 
database reflects 1,841 reported NMAC for all airspace areas. Of these 
NMACs, 50 involve a glider and another aircraft type, or 2.72% of 
reported NMACs over a 10-year period for an average of 5NMACs per year. 
In 2008, the last year data was available for all aircraft categories, 
statistics show there were 236,519 active aircraft, including 1,914 
gliders, or about 0.81% of the active fleet.
    Nationally, the removal of the glider exception from Sec.  91.215 
would help to prevent those instances where a glider NMAC occurs with 
an aircraft equipped with a Traffic Alert and Collision Avoidance 
System (TCAS).9 10 However, instances where removal of the 
glider exception from Sec.  91.215 help prevent a glider NMAC due to 
increased air traffic controller awareness are assumed negligible 
overall, because the operating areas for gliders are often in places 
with little or no radar coverage. Furthermore, because gliders can 
maneuver rapidly, glider flight paths are difficult for the Air Traffic 
Control (ATC) automation system to accurately project. Over the 10-year 
period reviewed, of the 50 reported NMACs involving a glider and 
another aircraft type, 7 involved a glider and part 121 or 135 air 
carriers required to have TCAS. Using this analysis, removal of the 
glider exception from Sec.  91.215 has the potential to reduce the NMAC 
occurrences by about 0.70 occurrences per year, or about 2 NMACs every 
3 years (0.38% of all reported NMACs per year over that period).

    \9\ This assumes all gliders are equipped with a transponder.
    \10\ TCAS provides two types of advisories, a Traffic Advisory 
(TA) and a Resolution Advisory (RA). TCAS can provide both types of 
advisories using another aircraft's transponder signal. A TA 
provides an aural alert ``TRAFFIC, TRAFFIC'' to the flight crew and 
places the other aircraft on a cockpit display showing the other 
aircraft's position, altitude and movement relative to the TCAS-
equipped aircraft. TCAS also computes the time to closest point of 
approach between the two aircraft. If this drops below a certain 
computed threshold, TCAS then provides a RA, which consists of aural 
commands and instrument cues to maneuver the aircraft vertically to 
avoid the threat.

    Assuming all of these NMACs would occur between gliders and air 
carrier aircraft,\11\ this would represent an incremental NMAC hazard 
of approximately 3.8 x 10-8/flight hour to the air carrier 
aircraft, based on air carrier flight hour data for years 2010-2014 
published on the NTSB's Web site. This rate of occurrence is within the 
acceptable hazard level guidelines for a Hazardous failure condition 
(not greater than the order of 1 x 10-7/flight hour) 
according to the FAA System Safety Handbook, Appendix B.\12\

    \11\ Air carrier aircraft are the fleet segment of greatest 
safety concern to the FAA for this contemplated rulemaking. These 
aircraft are required by regulation to be TCAS-equipped.
    \12\ Appendix B of the FAA System Safety Handbook defines a 
hazardous failure condition as one that reduces the capability of 
the system or the operator ability to cope with adverse conditions 
to the extent that there would be: Large reduction in safety margin 
or functional capability; Crew physical distress/excessive workload 
such that operators cannot be relied upon to perform required tasks 
accurately or completely; Serious or fatal injury to small number of 
occupants of aircraft (except operators); or Fatal injury to ground 
personnel and/or general public.

    Therefore, based on the nationwide rate of occurrence, safety risk 
data does not support a rule requiring glider operators to install a 
transponder device at this time. Furthermore, the number of gliders 
voluntarily equipping with collision avoidance systems has increased 
steadily. Per the General Aviation and Part 135 Activity Surveys, the 
number of gliders equipped with a transponder device has gone from 14% 
in 2006, to 24.3% in 2014, the last year this data was available.\13\

    \13\ Number of active gliders with transponders: 2014 GA Survey, 
Avionics Tables, Table AV.6. https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/.

    Locally in the airspace surrounding Reno, Nevada, the NTSB noted 
four TCAS Resolution Advisory (RA) events in the 30 days prior to the 
accident, each between a glider and a TCAS-equipped transport category 
aircraft operated under 14 CFR part 121.\14\ For these RAs to occur, 
the glider involved in each RA would have to be flying with an operable 
transponder (turned on).

    \14\ A-08-10 through 13, Safety Recommendations. National 
Transportation Safety Board, Washington, DC 20594, March 31, 2008. A 
copy of this letter is in the docket at www.regulations.gov, docket 
no. FAA-2015-2147.

    Although this data supports the value of transponders in avoiding 
collisions, since the accident, the FAA and local glider community have 
also taken several measures to mitigate the risk of midair collisions 
within and around Reno, NV. First, advisory information on the heavy 
glider activity unique to the local area was published in official FAA 
flight information publications including the Chart Supplement, Special 
Notices, and Standard Terminal Arrival Routes (STARs) for Reno/Tahoe 
International Airport after the event. Second, on October 29, 2010, a 
Letter of Agreement (LOA) was signed between representatives for the 
local glider

[[Page 94279]]

community and ATC facilities having control over the airspace. The LOA 
establishes an area and procedures for glider operations within 
positive controlled airspace in the Reno area. By establishing this 
area and these procedures, the LOA enhances airspace awareness and 
communication among the Oakland Air Route Traffic Control Center, 
Northern California Terminal Radar Approach Control, and the Pacific 
Soaring Council. Additionally, the LOA outlines entry and exit 
procedures into the operating areas and identifies pilot 
responsibilities to increase communication and situational awareness in 
the Reno area.\15\

    \15\ The LOA is posted in the docket at www.regulations.gov, 
docket no. FAA-2015-2147.

    Finally, the local glider community has undertaken a successful 
education campaign to prevent further accidents. According to the SSA, 
``Since the 2006 accident, the local glider community that flies near 
RNO has undertaken successfully to educate pilots on collision 
avoidance and to encourage the voluntary use of either FLARM or 
transponders. As a result of these voluntary efforts, the official ASRS 
database includes no new incidents with gliders not equipped with 
transponders in the RNO or MEV [Minden-Tahoe Airport] areas in 
[excepted] airspace since the release some 7 years ago of the NTSB 
report on the 2006 incident.'' \16\

    \16\ SSA comment letter posted in the docket at 
www.regulations.gov, docket no. FAA-2015-2147.

    The SSA, EAA, and several individual commenters opposing 
transponder equipage, noted that the glider involved in the 2006 Reno 
accident was equipped with a transponder, but at the time of the 
accident, the pilot operated the glider with the transponder turned 
off.\17\ The FAA acknowledges that in the 2006 accident, if the glider 
transponder were turned on, the Hawker aircraft would have received 
TCAS advisories.

    \17\ 14 CFR 91.215(c) states: While in the airspace as specified 
in paragraph (b) of this section or in all controlled airspace, each 
person operating an aircraft equipped with an operable ATC 
transponder maintained in accordance with Sec.  91.413 of this part 
shall operate the transponder, including Mode C equipment if 
installed, and shall reply on the appropriate code or as assigned by 
ATC. This collision occurred at approximately 16,000 feet MSL in 
Class E airspace (which extends upward from 14,500 feet MSL to 
flight level 180 throughout the National Airspace System).

2. Estimating Glider Transponder Cost From Removal of Glider Exception

    Approximately 138 commenters discussed the cost of requiring 
gliders to equip with transponders.\18\ Of those 138 commenters 
discussing cost, there were just 20 comments that could be 
characterized as in favor of requiring gliders to equip with 
transponders to some degree.

    \18\ Most comments addressed the cost of transponder equipage. A 
few comments addressed the cost to install other equipment such as 
ADS-B, TABS, and FLARM. The FAA sought comment on these technologies 
in the ANPRM. These alternatives and others are discussed later in 
this notice.

    Three commenters stated that transponders were inexpensive, but as 
shown below these commenters underestimated the cost of glider 
transponders as ``in the few hundred dollar range'' or ``less than 
$2000'' and/or ignored the cost of installation or assumed installation 
was easy. They did not address the concern that about half the glider 
population does not have an electrical system, which significantly 
increases the cost of transponder installation. These commenters were 
contradicted by more than 30 commenters who provided specific cost 
estimates for glider transponders and installation costs. Another 
commenter, in favor of removing the glider exception because he 
believed that the safety benefits justified the costs, conceded that 
transponders ``are indeed costly.''
    The FAA estimates the cost of requiring gliders to equip with 
transponders to be about $5,000 per glider and more than $7 million for 
the glider fleet. Owing to a lack of reliable data, the glider (and 
fleet) cost estimates do not take into account the possible significant 
cost of instrument panel modification. There may also be significant 
additional cost for older gliders that no longer have manufacturer 
support because they may require a FAA Form 337 (Major Repair and 
Alteration) approval if there is no prior approval (Supplemental Type 
Certificate (STC) or other previously approved installation).
    The fleet estimate assumes that (1) all active glider operators 
will want to operate in the currently excepted airspace and (2) the 990 
inactive gliders (total glider population of 2781--1791 active gliders) 
in the fleet will deregister upon rule implementation.\19\ The $7 
million fleet figure would be an underestimation to the extent these 
two assumptions are incorrect. Details of the estimates of cost per 
glider and glider fleet cost are shown in Table 1.

    \19\ Total number of gliders and number of active gliders: 2014 
GA Survey, Table 2.1.

                 Table 1--Glider Transponder Unit Costs
              Item                    Cost            Sources/notes
Transponder....................          $2,339  Cost based on the Trig
                                                  TT21 as it appears to
                                                  be the most popular
                                                  glider transponder.
Cabling........................             146  Aircraftspruce.com:
                                                  Trig TT21 including
                                                  custom harness--$2485.
Antenna........................             169  Cumulus-Soaring.com:
                                                  RAMI AV-74-1 Blade
                                                  Style Transponder or
                                                  DME Antenna: ``. . .
                                                  like the AV-74--but
                                                  with longer mounting
                                                  studs--which is nice
                                                  when trying to mount
                                                  it through a glider
Battery charger................              25  .......................
    Total Nonrecurring hardware           2,679  .......................
Installation...................           1,300  Average of 32 ANPRM
                                                  commenter estimates.
        Total Nonrecurring Cost           3,979  .......................
Batteries (every 2.5 years)....             600  Battery choice based on
                                                  comment by
                                                  Philadelphia Glider
                                                  Council: ``. . . one
                                                  [LiFePO4]18AH or two-
                                                  three 9 Ahs generally
                                                  sufficient for 10 hrs
                                                  of operation.''
                                                  Bioenno Power BLF-1209
                                                  LiFePo4 Battery 12V,
                                                  9AHr $100, charger
                                                  $25. Or BLF-1220 20AHr
                                                  $205, charger $30.
                                                  Duration based on
                                                  ANPRM comments.
Biannual inspection............             800  $200 per inspection.
                                                  Based on ANPRM

[[Page 94280]]

    Total Recurring Costs......           1,400  .......................

    The nonrecurring and recurring unit costs required to estimate the 
cost of a rule change eliminating the glider transponder exception are 
shown in Table 1.
    The FAA estimates the costs of such a rule change over a ten-year 
period for the existing U.S. glider fleet. This estimation is shown in 
Table 2.\20\ The cost of a rule change for new production of existing 
glider models and new certifications is not estimated owing to a lack 
of the necessary forecasts.

    \20\ The estimation takes into account an additional 
nonrecurring cost not shown in Table 1 of $400 for gliders without 
an electrical system.

                         Table 2--Ten-Year Cost of Removing Glider Transponder Exception
                                                                                   Non-recurring   PV recurring
                Year                   Item costs            Description               costs      costs @7% \21\
0..................................          $3,979  Hardware & Installation....          $3,979  ..............
1..................................  ..............  ...........................  ..............  ..............
2..................................             200  Bi-annual Inspection.......  ..............            $175
2.5................................             200  Battery Replacement........  ..............             169
3..................................  ..............  ...........................  ..............  ..............
4..................................             200  Bi-annual Inspection.......  ..............             153
5..................................             200  Battery Replacement........  ..............             143
6..................................             200  Bi-annual Inspection.......  ..............             133
7..................................  ..............  ...........................  ..............  ..............
7.5................................             200  Battery Replacement........  ..............             120
8..................................             200  Bi-annual Inspection.......  ..............             116
9..................................  ..............  ...........................  ..............  ..............
10.................................  ..............  ...........................  ..............  ..............
    Totals.........................  ..............  ...........................           3,979           1,009


    \21\ A discount rate of 7 percent is recommended by Office of 
Management & Budget, Circular A-94, ``Guidelines and Discount Rates 
for Benefit-Cost Analysis of Federal Programs,'' October 29, 1992, 
p. 8.
    \22\ Number of active gliders with electrical systems gliders: 
2014 GA Survey, Avionics Tables, Table AV.1. https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/.
    \23\ Number of active gliders with transponders: 2014 GA Survey, 
Avionics Tables, Table AV.6. https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/.

                 Total number of active gliders                        1791         Cost/glider     Total cost
Gliders with electrical systems \22\............................             699  ..............  ..............
Gliders with transponders \23\..................................             461  ..............  ..............
Gliders without electrical systems..............................            1092             400         436,800
Gliders without transponders....................................            1330           4,988       6,633,798
    Cost of rule removing glider exception......................  ..............  ..............       7,070,598
Note: Due to rounding, details may not add up to totals or multiply to products.

    Based on the risk reduction data discussed in the previous section 
and the estimated costs of equipage listed in this section, the FAA 
finds that the degree of risk reduction that could be expected by 
requiring transponder equipage for gliders does not justify the cost of 
requiring such equipage.

3. Alternatives to Transponders

    Several commenters called for ``low cost'' and ``affordable'' 
transponders (such as a portable transponder) and ADS-B, TABS, or FLARM 
equipment. The NTSB noted the FAA published a final rule on May 28, 
2010, that added requirements for ADS-B Out equipage that, if combined 
with transponder usage, would result in increased traffic awareness and 
collision avoidance. The NTSB also commented in response to this ANPRM 
that TABS may be an acceptable alternative as it is detectable by both 
TCAS and ADS-B-In equipped aircraft.
    Since the 2006 accident, technologies have developed and 
alternatives are available that have the potential to mitigate risk, 
such as TABS, FLARM, ADS-B, local LOA with ATC facilities, and ongoing 
outreach and education. Of the technological solutions identified here, 
the ones that offer the best potential to avoid collision with TCAS-
equipped aircraft (besides transponder equipage) are TABS or a rule-
compliant ADS-B Out system, because those systems make the glider 
visible to TCAS-equipped aircraft, ATC or both.
    The TABS standard provides for a reduction in the transmission rate 
and allows for a ``non-aviation grade'' GPS engine, in order to drive 
unit cost down while still maintaining an acceptable level of service 
to be considered a client in the NAS, where collision avoidance and 
ADS-B systems coexist. There are currently no TSO authorization holders 
for TABS equipment. However, we are aware that certain manufacturers 
currently have TABS systems in development.
    Some commenters recommended that the FAA allow use of portable

[[Page 94281]]

transponders, stating they were lower cost than fixed transponder 
installations and relatively affordable. While portable transponders 
may meet the TSO performance requirements, they are not approved for 
use unless they are actually installed in the aircraft. A key reason 
for this is placement of the transponder antenna in the aircraft. If 
the transponder antenna is not placed correctly, the aircraft may not 
be electronically detectable to other aircraft or ATC.
    Other commenters recommended that the FAA encourage equipage of 
FLARM systems. In this regard, the FAA notes that a variant of FLARM, 
known as PowerFLARM, will make a transponder or ADS-B Out equipped 
aircraft detectable to the PowerFLARM-equipped aircraft (such as a 
glider). However, a glider that is equipped with any version of FLARM 
will not be electronically detectable to the other aircraft unless both 
aircraft are FLARM equipped. In view of these factors, the FAA 
concludes that FLARM systems may provide a safety benefit (particularly 
for avoidance of collisions between gliders, and for PowerFLARM 
equipped gliders, some benefit for avoidance of collisions with powered 
aircraft). However, the FAA does not view FLARM (including PowerFLARM) 
as the most effective system to support collision avoidance with 
powered aircraft since a FLARM system may not make the glider 
detectable to the aircraft that must give way. Transponders, TABS, and 
ADS-B Out offer better protection against collisions with powered 
aircraft because those systems aid visual acquisition of the glider by 
the powered aircraft flightcrew, consistent with right of way 

    \24\ Section 91.113(d)(2) states that ``A glider has the right 
of way over powered parachute, weight-shift-aircraft, airplane, or 

    The FAA will continue to consider surveillance system alternatives 
for gliders for their feasibility and potential to improve safety.

4. Other Comments

    Several commenters were in favor of removing the current glider 
exception for certain high-density airspace areas. One commenter, 
otherwise strongly in favor of removing the glider exception, suggested 
an exception for gliders involved in training below 5,000 feet above 
ground level (AGL). The FAA has determined not to propose any changes 
to the rules for specific airspace areas because the accident and 
incident history cited in the NTSB recommendation has occurred 
predominantly around one specific airspace area, Reno, NV. The FAA has 
determined that the post accident mitigations for the Reno area 
discussed previously in this notice mitigate the risk for that specific 
    Another commenter stated, ``the FAA should make clear that 
installing a transponder, encoder, antenna, an extra battery or 
batteries and possible solar panels are all considered `minor 
modifications' which can be signed off by the installing technician 
based on his judgment.'' This commenter and several others, in 
opposition of the removal of the glider exception, also called for 
exceptions for older gliders. The FAA finds that rulemaking is not 
necessary at this time for any gliders, but points to current guidance 
available to assist in installation and approval of transponder systems 
in gliders and sailplanes for operators wishing to voluntarily 

    \25\ Information for Operators (InFO) 09009, Installation and 
Approval of Transponder Systems in Gliders/Sailplanes, dated June 
10, 2009.

    The AAJ listed glider color, construction materials, and slender 
profiles as contributing factors to lack of pilot visibility or radar 
detection and further identified Instrument Flight Rule congested areas 
as concerns of undeniable risk, especially the parameters of Class B 
airspace. These sentiments were largely shared amongst both adverse and 
favorable commenters, offering similar solutions or variations thereof. 
The FAA has discussed its determination regarding specific airspace 
areas above. With regard to the other comments identified here, the 
FAA's decision in this notice includes consideration of those comments.

Reason for Withdrawal

    After consideration of all comments received, the FAA is 
withdrawing Notice No. 15-05. The FAA finds that the high cost of 
transponder equipage and the limited safety benefit that is likely to 
result from requiring such equipage do not support rulemaking at this 
time. Additionally, as discussed above, the FAA has determined that a 
proposal to require gliders to equip with ``low-cost'' alternatives to 
transponders is not supportable at this time.
    NTSB safety recommendations, resulting from the 2006 midair 
collision with a glider, indicated that although the glider was 
equipped with a transponder, the transponder was turned off. After 
further analysis of safety-related statistics over a 10-year period 
(August 2005-August 2015) the ASRS database reflects 1841 reported NMAC 
for all airspace areas. The FAA found data that indicates that removal 
of the glider exception from Sec.  91.215 would have the potential to 
reduce the NMAC occurrences by about 0.70 occurrences per year, or 
about 2 NMACs every 3 years (0.38% of all reported NMACs per year over 
that period).


    When further testing, research, and conclusive data is available 
that reflect alternative mitigations, a broader, more harmonized 
proposal may better serve the public interest. Withdrawal of Notice No. 
15-05 does not preclude the FAA from issuing another notice on the 
subject matter in the future or committing the agency to any future 
course of action. The agency will make any necessary changes to the 
regulations through a notice of proposed rulemaking (NPRM) with the 
opportunity for public comment.
    Although the FAA has determined that a regulatory course of action 
is not warranted at this time, the FAA will continue to work with local 
glider communities, encourage the voluntary equipage of transponders in 
gliders and encourage the use of TABS. The FAA continues to recommend 
that all glider aircraft owners equip their gliders with a transponder 
meeting the requirements of Sec.  91.215(a), a rule-compliant ADS-B Out 
system, or a TABS device. In consideration of the above factors, the 
FAA withdraws Notice No. 15-05, published in 80 FR 34346, on June 16, 

    Issued under authority provided by 49 U.S.C. 106(f), 44701(a), 
and 40103 in Washington, DC, on December 16, 2016.
Gary A. Norek,
Deputy Director, Airspace Services.
[FR Doc. 2016-30910 Filed 12-22-16; 8:45 am]