Section 2. Evaluating Aeronautical Effect
29-2-1. AERONAUTICAL REVIEW
a. At a minimum the following items must be
studied as part of any aeronautical review:
1. Location of the proposed laser operation.
2. Aircraft operations affected by the proposed
operation.
3. Air traffic flows in the proposed area of the
operation.
4. An analysis of adverse effect conducted by
the ATC facility having control over the affected
airspace.
5. A safety analysis conducted by the Flight
Standards Division regarding the effects on flight
crews.
6. For visible laser systems, plot the LFZ, CFZ,
and SFZ (if applicable) for all potentially affected
airports and evaluate any control measures, which
may mitigate any adverse effect.
7. The effective irradiance levels listed below
must not be exceeded in the corresponding zones.
(a) A laser-free zone is limited to 50nW/cm2
or less.
(b) A critical flight zone is limited to
5mW/cm2 or less.
(c) A sensitive flight zone is limited to
100mW/cm2 or less.
(d) A normal flight zone, as well as the
above zones, is limited to the MPE or less.
EXCEPTION-
The LFZ, CFZ, and SFZ need only be considered for
visible laser systems. Further, when control measures
(e.g., safety observers) mitigate all hazards or other issues
raised by the aeronautical review, irradiance levels may
exceed the above levels.
b. Consult FDA/CDRH personnel for technical
advice. (e.g., regarding repetitively pulsed laser
calculations)
c. Scientific/research lasers in accordance with
21 CFR Section 1010.5 may be exempt from Title 49
and, in addition, may not be able to comply with the
above procedures. Regardless of whether or not a
proponent is exempt from the provisions, a proposal
is still reviewed using the above procedures.
29-2-2. LOCAL LASER WORKING GROUP
(LLWG)
When necessary, the service area office may convene
a LLWG to assist in evaluating proposed laser
operation.
a. The service area office must forward information on a proposed outdoor laser operation to the local
air traffic facility.
b. The local air traffic facility must act as the focal
point for the LLWG. Other participants may include,
but not limited to, representatives from the ARTCC,
ATCTs, airport management, airspace users, city/county/state officials, other government agencies,
military representatives, qualified subject experts,
laser manufacturers, etc.
c. The LLWG must resolve issues regarding local
laser operations and forward recommendations to the
service area office as soon as practicable.
29-2-3. PROTECTION DISTANCE
CALCULATIONS
a. The laser system power range table
(TBL 29-2-1) provides the applicable protection
distances along the axis of the laser beam with a
1mrad divergence. This table must not be used to
determine the protection distances for repetitively
pulsed (RP) lasers. Proponents are required to
resolve RP laser system calculations with the FDA or
laser manufacture before submitting a completed
Laser Configuration Worksheet to the FAA.
b.
TBL 29-2-2 lists sine and cosine values to be
used in determining the vertical and horizontal
distances to be protected from the laser source. The
distances obtained from
TBL 29-2-1 are multiplied
by these values to determine the appropriate vertical
and horizontal distances to be protected based on the
minimum and maximum vertical angles. Differences
in site/ground elevations should be considered.
c. The vertical component of the protection
distance may be determined by multiplying the laser
distance from
TBL 29-2-1 by the sine of the
maximum elevation angle of the laser beam from
TBL 29-2-2. For example, vertical component =
protection distance x sine of the maximum elevation
angle.
d. The horizontal component of the protection
distance may be determined by multiplying the laser
distance from
TBL 29-2-1 by the cosine of the
minimum elevation angle of the laser beam from
TBL 29-2-2. For example, horizontal component =
protection distance x cosine of the minimum
elevation angle.
e. Do not reduce calculated distances for
correction factor techniques unless validated by
FDA/CDRH.
f. All distances must be rounded up to the next
100-foot increment. See example problems 1, 2, and
3 that follow the Vertical and Horizontal Component
Table,
TBL 29-2-2.
29-2-4. CONTROL MEASURES
Physical, procedural, and automated control measures may be used to ensure that aircraft will not be
exposed to levels of illumination greater than the
respective maximum irradiance levels established for
the various protected zones.
a. Physical beam stops at the system location or at
a distance may be used to prevent laser light from
being directed into protected zones.
b. The beam divergence, azimuth, elevation, and
output power may be adjusted to meet appropriate
irradiance levels.
c. Beam direction should be specified by giving
bearing in the azimuth scale 0 - 360 degrees and
elevation in degrees ranging from 0 - 90 degrees,
where zero degrees is horizontal and +90 degrees is
vertical. Bearings shall be given in both true and
magnetic north.
d. Manual operation of a shutter or beam
termination system can be used in conjunction with
safety observers. Observers must have an adequate
view of the airspace surrounding the beam's paths to
a distance appropriate to the affected airspace.
e. Scanning of a laser system that is designed to
automatically shift the direction of the laser beam can
be used. However, scanning safeguards must be
found to be acceptable by the FDA and the FAA. The
FDA recommendation must be included in the
proposal to the FAA.
NOTE-
Scanning may reduce the level of illumination; however,
it may also increase the potential frequency of an
illumination.
f. Any automated system designed to detect
aircraft and automatically terminate the beam,
redirect the beam, or shutter the system, must be
reviewed and found to be acceptable by the FAA
before the use of the device may be accepted as a
control measure.
TBL 29-2-1
LASER SYSTEM POWER RANGE TABLE
CW Laser Beam Divergence: 1 Milliradian
* NOT TO BE USED WITH RP SYSTEMS
|
W/cm^2 --->
|
2.60E-03
|
1.00E-04
|
5.00E-06
|
5.00E-08
|
|
|
CW Laser
Power (W)
|
Nominal Ocular
Hazard Distance
NOHD (ft)
|
Sensitive Zone
Exposure Distance
SZED (ft)
|
Critical Zone
Exposure Distance
CZED (ft)
|
Laser-Free Zone
Exposure Distance
LZED (ft)
|
LZED
(nm)
|
|
1
|
726
|
3701
|
16553
|
165527
|
27
|
|
2
|
1026
|
5234
|
23409
|
234090
|
39
|
|
3
|
1257
|
6411
|
28670
|
286700
|
47
|
|
4
|
1452
|
7403
|
33105
|
331053
|
54
|
|
5
|
1623
|
8276
|
37013
|
370129
|
61
|
|
6
|
1778
|
9066
|
40546
|
405456
|
67
|
|
7
|
1920
|
9793
|
43794
|
437942
|
72
|
|
8
|
2053
|
10469
|
46818
|
468180
|
77
|
|
9
|
2178
|
11104
|
49658
|
496580
|
82
|
|
10
|
2295
|
11704
|
52344
|
523441
|
86
|
|
11
|
2407
|
12276
|
54899
|
548990
|
90
|
|
12
|
2514
|
12822
|
57340
|
573401
|
94
|
|
13
|
2617
|
13345
|
59681
|
596815
|
98
|
|
14
|
2716
|
13849
|
61934
|
619344
|
102
|
|
15
|
2811
|
14335
|
64108
|
641082
|
106
|
|
16
|
2903
|
14805
|
66211
|
662106
|
109
|
|
17
|
2993
|
15261
|
68248
|
682484
|
112
|
|
18
|
3080
|
15703
|
70227
|
702270
|
116
|
|
19
|
3164
|
16134
|
72151
|
721514
|
119
|
|
20
|
3246
|
16553
|
74026
|
740257
|
122
|
|
25
|
3629
|
18506
|
82763
|
827633
|
136
|
|
30
|
3976
|
20273
|
90663
|
906626
|
149
|
|
35
|
4294
|
21897
|
97927
|
979268
|
161
|
|
40
|
4591
|
23409
|
104688
|
1046882
|
172
|
|
45
|
4869
|
24829
|
111039
|
1110386
|
183
|
|
50
|
5133
|
26172
|
117045
|
1170450
|
193
|
|
55
|
5383
|
27449
|
122758
|
1227578
|
202
|
|
60
|
5623
|
28670
|
128216
|
1282163
|
211
|
|
65
|
5852
|
29841
|
133452
|
1334518
|
220
|
|
70
|
6073
|
30967
|
138489
|
1384895
|
228
|
|
75
|
6286
|
32054
|
143350
|
1433502
|
236
|
|
80
|
6492
|
33105
|
148051
|
1480515
|
244
|
|
85
|
6692
|
34124
|
152608
|
1526079
|
251
|
|
90
|
6886
|
35113
|
157032
|
1570323
|
258
|
|
95
|
7075
|
36076
|
161335
|
1613353
|
266
|
|
100
|
7259
|
37013
|
165527
|
1655266
|
272
|
|
105
|
7438
|
37927
|
169614
|
1696143
|
279
|
|
110
|
7613
|
38819
|
173606
|
1736057
|
286
|
|
115
|
7784
|
39692
|
177507
|
1775075
|
292
|
|
120
|
7952
|
40546
|
181325
|
1813253
|
298
|
|
125
|
8116
|
41382
|
185064
|
1850643
|
305
|
|
130
|
8276
|
42201
|
188729
|
1887293
|
311
|
|
135
|
8434
|
43005
|
192324
|
1923245
|
317
|
|
140
|
8589
|
43794
|
195854
|
1958537
|
322
|
|
145
|
8741
|
44569
|
199320
|
1993204
|
328
|
|
150
|
8890
|
45331
|
202728
|
2027278
|
334
|
|
155
|
9037
|
46081
|
206079
|
2060789
|
339
|
|
160
|
9182
|
46818
|
209376
|
2093764
|
345
|
* The FDA may be contacted to validate data for repetitively pulsed lasers.
NOTE-
[1] To determine the NOHD for lasers having divergence values other than 1.0 mrad use the formula - NOHD @ 1.0 mrad
÷ mrad (actual divergence) = NOHD.
EXAMPLE-
Power 40W, Divergence 7 mrad
NOHD 40W @ 1.0 mrad = 4,591
4,591 ÷ 7 = 656 NOHD. Rounded up to nearest hundred feet = 700 feet.
(A beam divergence of .7 would make this calculation 7,000 feet)
* The proponent validates repetitive pulsed information with the FDA and submits a completed laser
configuration worksheet.
TBL 29-2-2
VERTICAL AND HORIZONTAL COMPONENTS
VERTICAL COMPONENT
|
Maximum
Elevation Angle
|
Sine
(vertical component
multiplier)
|
|
90
|
1.0000
|
|
85
|
.9962
|
|
80
|
.9848
|
|
75
|
.9659
|
|
70
|
.9397
|
|
65
|
.9063
|
|
60
|
.8660
|
|
55
|
.8192
|
|
50
|
.7660
|
|
45
|
.7071
|
|
40
|
.6428
|
|
35
|
.5736
|
|
30
|
.5000
|
|
25
|
.4226
|
|
20
|
.3420
|
|
15
|
.2588
|
|
10
|
.1737
|
|
5
|
.0872
|
|
0
|
.0000
|
HORIZONTAL COMPONENT
|
Minimum
Elevation Angle
|
Cosine
(horizontal component
multiplier)
|
|
0
|
1.0000
|
|
5
|
.9962
|
|
10
|
.9848
|
|
15
|
.9659
|
|
20
|
.9397
|
|
25
|
.9063
|
|
30
|
.8660
|
|
35
|
.8192
|
|
40
|
.7660
|
|
45
|
.7071
|
|
50
|
.6428
|
|
55
|
.5736
|
|
60
|
.5000
|
|
65
|
.4226
|
|
70
|
.3420
|
|
75
|
.2588
|
|
80
|
.1737
|
|
85
|
.0872
|
|
90
|
.0000
|
LASER PROBLEM SOLUTIONS
EXAMPLE PROBLEM 1:
Laser output power = 15 watts
Laser beam divergence = 1.0 mrad
Find: Laser protection distances:
1. Find
TBL 29-2-1 at 15 watts in the Laser Output
Power column.
2. Proceed horizontally and read: NOHD of
2,811 feet, CFZ of 64,108 feet, SFZ 14,335 feet.
Answer: (with rounded up distances): NOHD
2,900 feet, CFZ 64,200 feet, SFZ 14,400 feet.
EXAMPLE PROBLEM 2
Laser output = 18 watts
Laser beam divergence = 1.0 mrad
Maximum elevation angle 60°
Minimum elevation angle 20°
Find:Vertical and horizontal distances to be protected:
1. Laser distance (from
TBL 29-2-1) = 3,080 feet.
2. Sine of 60° maximum elevation angle (from
TBL 29-2-2) = 0.8660.
3. Find altitude by multiplying 3,080 feet
by 0.8660 = 2,667 feet.
4. Cosine of 20° minimum elevation angle (from
TBL 29-2-2) = 0.9397
5. Find horizontal distance by multiplying 3,080 feet by
0.9397 = 2,894 feet.
Answer: Minimum required protected airspace
is 2,700 feet vertically and 2,900 feet horizontally from
the laser source.
EXAMPLE PROBLEM 3
Power = 25 watts
Laser NOHD at 1 mrad = 3,629 feet.
Beam Divergence = .7 mrad
Find: Actual NOHD
1. Find actual NOHD by dividing the NOHD at 1 mrad
divergence (3,629 feet) by actual divergence
(.7 mrad).
2. 3629 feet. ÷ .7 = 5184 feet.
Answer: NOHD 5,200 feet (rounded up)
