United States of America

Federal Aviation Administration

Aviation System Standards

Flight Inspection Operations Division

Charles J. Barbeau

**TRANSPONDER LANDING SYSTEM FLIGHT INSPECTION**

**[ABSTRACT]{.underline}**

The Transponder Landing System (TLS) is essentially a
computer-controlled pair of signal generators transmitting \"ILS
Look-Alike\" signals to guide the intended single aircraft from its
known position along an \"ILS-Type\" approach path. Precise aircraft
location is derived from time and carrier signal phase angle differences
of the aircraft transponder return as it arrives at ground sensor
antennas. Only one aircraft at a time can use the TLS.

Airborne evaluation of the TLS requires some traditional Instrument
Landing System (ILS) measurement techniques and modifications to ILS
inspection parameters checklists. This paper discusses the U.S.
philosophy and process for these inspections. Lessons learned during
prototype testing and results of flight inspections are presented. Also
discussed are the challenges to further adapt flight inspection methods
and equipment to support future use of the TLS in increasingly difficult
siting conditions.

[CONSIDERATIONS]{.underline}

Although the TLS produces an ILS signal, the procedures and flight
inspection specialists must consider the applicable system differences
to efficiently accomplish their tasks. For data dependent flight
inspections, the capability of checking non-traditionally sited
approaches may require software modification. Procedural design may be
more intricate to best use the TLS capability in adverse sites. Flight
Inspectors may need familiarization training to avoid TLS peculiarities
being perceived as defects and inspectors may need to remember the
"roots" of the profession to design inspection methods to suit their
particular requirements.

**[Procedural Design]{.underline}**

The design of the Instrument Approach Procedure is the same as for a
traditional ILS, with the exception of the need for a fix within the TLS
tracking volume and defined by another navigation source. This \"TLS
Acquisition Point\" (TAP) defines the earliest point in the procedure
where the pilot should request TLS \"Acquisition\" which activates the
guidance. If \"Acquisition\" is requested outside the service volume,
the system will perform a Built-in-test (BIT) and, failing to find the
aircraft transponder code, return to \"Standby Mode\". The BIT generates
a short test signal that a pilot could confuse with actual
\"Acquisition\" followed by some system failure. If a TAP fix is on the
localizer course, the holding pattern should either be totally inside or
outside the glide slope tracking volume to avoid the automatic \"Abort\"
which occurs when the aircraft departs the service volume of either the
localizer or glide slope. Holding on normal procedures would place the
aircraft outside the standard glide slope service volume on the outbound
leg. The easiest remedy for this situation is to configure the TLS glide
slope service volume to encompass the entire holding pattern. Figure 1
is the approach plate for the Atlantic City test station, which was
produced prior to the requirement for a TAP.

**Figure 1**

**Typical TLS Approach Plate**

![](media/image3.wmf)

**[Screening]{.underline}**

The TLS is most likely to be installed in locations unsuitable for an
ILS due to adverse terrain or buildings. The line-of-sight screening by
these features may preclude signal reception at planned procedural
altitudes. It is important that the procedures specialist consider
signal screening effects in the design of the approach. The flight
inspector also should plan inspection profiles to avoid unnecessarily
looking for a signal where screening precludes their reception.
Verifying a projected facility restriction is easier and more efficient
than defining one through multiple runs at increasing altitudes. The TLS
installers, who also provide other facility data, measure screening
angles based on the transponder link.

**[U.S. Flight Inspection Policy]{.underline}**

FAA Order 8200.40A, Flight Inspection of the Transponder Landing System
(TLS), the current U.S. guidance document, was derived from ILS
procedures in the U.S. Standard Flight Inspection Manual, FAA Order
8200.1. There are no differences between ILS and TLS tolerances for
measured parameters. The separate, \"stand-alone\" policy order is
relatively easy to amend as increased knowledge of TLS warrants.
Eventually, the TLS peculiarities will be included in the ILS guidance
of Order 8200.1 and the separate order cancelled.

**[Flight Inspection Profiles]{.underline}**

The flight inspection checks needed to determine system adequacy and
accuracy are the same as for ILS; however, the scope of the inspection
can be greatly reduced due to the nature of the TLS. The guidance
signals are produced by computer-controlled RF signal generators rather
than by individually phased antennas. There is no need to check the
effects of phase changes through equipment deterioration or terrain
irregularities. System displacement sensitivity/width is also a
computer-controlled function unaffected by the carrier and sideband
power ratios of the traditional ILS; therefore, there are no width
monitors. The remaining checks are for signal coverage and calibration
of transponder power and receiver sensitivity and guidance course/path
alignment and width. An example of the currently used U.S. commissioning
profile is in Figure 3.

**[Transponder Optimization and Validation]{.underline}**

The installation team normally establishes ground interrogator power
levels, side lobe suppression, and receiver sensitivity using non-flight
inspection aircraft. These aircraft may not have a well-calibrated
transponder, and validation of these adjustments must be by flight
inspection with a calibrated transponder. Both the pre-commissioning
set-up and flight inspection validation are arcs at the distances and
limits indicated in Steps 1 through 8 in Figure 3. With the exception of
the 12 nm arcs, which can provide valid course width information, no
usable guidance information is received during these checks.

**[Peculiarities]{.underline}**

The TLS has unique attributes that require changes in flight inspection
techniques and increased situational awareness by the flight inspection
crew. The sharp edge of the tracking volume may make maneuvering the
aircraft to intercept a 35° clearance arc and being \"Acquired\" prior
to the measurement area difficult in a limited airspace situation. In
these cases, it may be necessary to start the run inside the guidance
volume and fly outbound to the edges of required coverage. The approach
used to validate the 7° upper limit of localizer coverage will place the
aircraft outside the glide slope service volume, resulting in an
automatic \"TLS Abort\". The solution to this is to have maintenance
turn the glide slope function OFF during this check. Neither of these
two situations makes flight inspection difficult.

One TLS feature that has caused extra work is the maximum glide slope
proportional clearance value of approximately 200 μA. To ensure obstacle
clearance while maintaining the beyond full scale value of 180 μA, it is
typical in ILS flight inspection to descend further below path
maintaining approximately 220 μA of fly-up signal. This allows some
maneuvering room to preclude aircraft pitch changes in the last part of
the approach. With a maximum of 200 μA proportional to aircraft
displacement available, the inspector has no means to judge whether the
aircraft is barely at or well below the 200 μA point. This lack of
judgment ability has resulted in several runs to validate clearance
below path. As the TLS is likely to be at a challenging airport and this
run places the flight inspection aircraft close to obstacles, this
feature causes concern by flight inspectors. This situation affects only
the flight inspection aircraft and is of no concern for normal users.

**[Marker Indications]{.underline}**

The TLS produces aural \"Pseudo Marker Beacon\" indications in a
rectangular area at programmed Outer and Middle Marker locations along
the approach path. The \"Outer Marker\" consists of continuous 700 Hz
dashes keyed at 180 characters per minute, and the \"Middle Marker\"
indication is alternating 2000 Hz dots and dashes keyed at a 120 per
minute rate. As these \"Markers\" are transmitted on the localizer audio
and not from a 75 MHz transmitter, they do not light the normal marker
indicator lights, and their adequacy cannot be measured by reference to
light activation signal level. To measure the width along course, it is
necessary to manually note the amount of time that the aural indication
is present and apply the aircraft ground speed. The most practical
method is to mark the recordings at the applicable points. The major
axis should be verified in the same way, except through flight along the
localizer off-course indication. As the indications are solely
determined by the horizontal position of the aircraft, height deviations
have no effect on width. Any variations in width from check to check can
most likely be attributed to the aural acuity and reaction time of the
analysts.

**[Theodolite Procedures]{.underline}**

Use of a theodolite as the positional truth source requires additional
survey work, as the instrument cannot be placed in relation to antennas
that exist only in mathematics. For a standard runway centerline
approach, the apparent localizer antenna will most likely be on the
runway at the point of theoretical emanation designed to produce a
tailored course width of 700 feet at threshold. The glide slope apparent
antenna will be on the runway centerline at the procedural touchdown
point. For these installations, theodolite use, therefore, requires
runway closure.

As some TLS procedures will be to airports which cannot support
straight-in procedure, we must adapt the measurement techniques to fit
the situation. For Localizer Directional Aid (LDA) procedures not
aligned with a runway, the apparent localizer and glide slope antennas
will most likely not be on the runway. The only way to use a theodolite
will be to use surveyed points representing both apparent antennas. To
check the \"localizer\", the theodolite should be located at the
\"apparent localizer\" surveyed point, and aimed along the procedural
centerline, which can be defined by reference to the point where it
crosses the extended runway centerline. Consideration must be given to
any actual structures which may occupy the location of the \"apparent\"
antenna. The theodolite may have to be moved forward or backward along
the procedural course, causing some amount of parallax determined by the
amount of theodolite displacement from optimum. Minor parallax errors
will have negligible effect on the centerline and measured structure but
will induce some error in width measurements. The correct glide slope
theodolite position is easily determined by reference to the eyepiece
height corresponding with the glide angle. It is important that these
theodolite locations be permanently marked to avoid measurement errors
induced by incorrect positioning on subsequent checks. Figure 2 depicts
possible theodolite locations to support the inspection of a TLS sited
for an \"LDA/with GS\" approach.

**Figure 2**

**Theodolite Locations for TLS LDA**

**with GS Configuration**

**[Flight Inspection Results]{.underline}**

Only one TLS has so far been commissioned for Instrument Flight Rules
(IFR) use. Several others are installed and awaiting sponsorship and
procedural design.

[Subic Bay, Philippines]{.underline}. This station was commissioned in
1998 as an 8.87° offset LDA with Glide Slope with an approach course
through a rugged mountain valley. The 420-feet Height Above Touchdown
(HAT) minima was dictated by obstructions. Line-of-sight screening
caused coverage restrictions beyond 7° from centerline. Maximum
localizer and glide slope structure in the procedural use area was
approximately 66% of tolerance.

[Atlantic City, New Jersey]{.underline}. This system was installed as
the FAA test-bed. Commissioning profiles were flown to support glide
angles of 2.5, 3.0, and 4.0°. Signal structure was well within Category
I tolerances at all angles; but at the intended procedural altitudes for
the 2.5° approach, coverage was unsatisfactory beyond 14 miles below
1725 feet above site elevation. Both the 2.5 and 3.0° procedures also
were unusable beyond 17.3 miles below 2425 feet above site elevation.

[Pullman, Washington]{.underline}. This system is still in a Visual
Flight Rules Operational Demonstration status. This facility is
completely surrounded by significantly higher terrain, resulting in \"an
airport in a bowl\". Signal screening resulted in low altitude coverage
restrictions off-course and beyond 13 miles on course. Maximum localizer
structure was 4 μA, and the maximum glide slope structure above the 300
ft HAT decision height was 20 μA. At ILS point \"C\", angle alignment
resulted in a measured structure of 38 μA, resulting in a glide slope
restriction below decision height. Flight inspection of an approach
software correction for this restriction has not yet been accomplished.

[Watertown, Wisconsin]{.underline}. Another \"airport-in-a-bowl\", this
has been the site of some testing which indicates the facility will have
screening restrictions.

**[Long-Term Stability Data]{.underline}**

A result of changes in direction by the FAA in the acceptance of the TLS
has been the inability to gather periodic flight inspection results on
any one facility. No data yet exists to show any signal quality changes
over an extended period. As Atlantic City is the base for some FAA
flight inspection aircraft and TLS facilities are now in the flight
inspection aircraft database, it is now possible to economically and
easily perform a flight inspection approach on a frequent basis. These
samples may provide information on signal stability much earlier than
can be gathered only on periodic flight inspections.

**[Future Needs]{.underline}**

The present international standards for ILS address only the traditional
runway centerline-oriented approach path. Offset ILS and TLS
installations will become more common as precision approaches are
demanded at more challenging airfields. These installations may have
Decision Heights and Missed Approach Points more than two miles from
touchdown while users desire signals for a stabilized approach
completely to the runway. Service volume requirements must be redefined
to address these issues. As the TLS has the capability to provide a
curved approach path similar to Microwave Landing Systems, we must adapt
inspection methods, standards, and equipment to measure signal adequacy.
Some conceptual work has been done on curved-path evaluations; that work
must continue so that flight inspection is ready before the TLS to avoid
delays in providing service.

**[CONCLUSION]{.underline}**

The TLS can provide a satisfactory Category I \"ILS-Like\" instrument
approach to many airports unsuitable for traditional ILS equipment.
Flight inspection can use many standard ILS inspection techniques to
determine the adequacy of the guidance for most installations but
creative uses of the TLS call for adaptation of inspection services.

**[RECOMMENDATIONS]{.underline}**

1\. Increase tracking and guidance volume distance limits as necessary
to provide signals beyond the formally required "Service Volume" to give
pilots a signal where they expect one.

2\. Increase Glide Slope proportion deviation limit to approximately 225
μA to ease flight inspection

**Figure 3**

**TLS Commissioning Profile**

(continued on next page)

<table>
<colgroup>
<col style="width: 4%" />
<col style="width: 9%" />
<col style="width: 9%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 22%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Step</strong></td>
<td><p><strong>Guidance TX</strong></p>
<p><strong>Config</strong></p>
<p><strong>(LOC/GS)</strong></p></td>
<td><p><strong>Ground</strong></p>
<p><strong>Xpndr</strong></p>
<p><strong>Config</strong></p></td>
<td><p><strong>Aircraft</strong></p>
<p><strong>Xpndr</strong></p>
<p><strong>Settings:</strong></p>
<p><strong>FI</strong></p>
<p><strong>Sel/Low</strong></p>
<p><strong>Pwr Sel</strong></p></td>
<td><p><strong>Type</strong></p>
<p><strong>Maneuver</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>Distance</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>AZ</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>Alt</strong></p>
<p><strong>(MSL)</strong></p></td>
<td><p><strong>Stop</strong></p>
<p><strong>Distance</strong></p></td>
<td><p><strong>Stop</strong></p>
<p><strong>AZ</strong></p></td>
<td><p><strong>Stop</strong></p>
<p><strong>Alt</strong></p>
<p><strong>(MSL)</strong></p></td>
<td><strong>Remarks</strong></td>
</tr>
<tr class="even">
<td>1</td>
<td>Norm/Norm</td>
<td><p>P1/P3 "ON"</p>
<p>Attenuation</p>
<p>"IN", P2</p>
<p>"OFF"</p></td>
<td>ON/OFF</td>
<td>ARC</td>
<td>22 nm</td>
<td>5° Left</td>
<td>GSI</td>
<td>22 nm</td>
<td>15° Right</td>
<td>GSI</td>
<td>System set-up. Runs not needed if set during pre-commissioning.</td>
</tr>
<tr class="odd">
<td>2</td>
<td>Norm/Norm</td>
<td><p>P1/P3 "ON"</p>
<p>Attenuation</p>
<p>"IN", Ps</p>
<p>"OFF"</p></td>
<td>ON/OFF</td>
<td>ARC</td>
<td>22 nm</td>
<td>5° Right</td>
<td>GSI</td>
<td>22 nm</td>
<td>15° Left</td>
<td>GSI</td>
<td>System set-up. Runs not needed if set during pre-commissioning.</td>
</tr>
<tr class="even">
<td>3</td>
<td>Norm/Norm</td>
<td><p>P1/P3 "ON",</p>
<p>P2 "ON"</p>
<p>(STANDARD)</p></td>
<td>ON/OFF</td>
<td>ARC</td>
<td>12 nm</td>
<td>10° Left</td>
<td>GSI</td>
<td>12 nm</td>
<td>90° Right</td>
<td>GSI</td>
<td>System set-up. Runs not needed if set during pre-commissioning.</td>
</tr>
<tr class="odd">
<td>4</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/OFF</td>
<td>ARC</td>
<td>12 nm</td>
<td>10° Right</td>
<td>GSI</td>
<td>12 nm</td>
<td>90° Left</td>
<td>GSI</td>
<td>System set-up. Runs not needed if set during pre-commissioning.</td>
</tr>
<tr class="even">
<td>5</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/OFF</td>
<td>ARC</td>
<td>22 nm</td>
<td>5° Left</td>
<td>GSI</td>
<td>22 nm</td>
<td>15° Right</td>
<td>GSI</td>
<td>Expect no guidance signal.</td>
</tr>
<tr class="odd">
<td>6</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/OFF</td>
<td>ARC</td>
<td>22 nm</td>
<td>5° Right</td>
<td>GSI</td>
<td>22 nm</td>
<td>15° Left</td>
<td>GSI</td>
<td>Expect no guidance signal.</td>
</tr>
<tr class="even">
<td>7</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/OFF</td>
<td>ARC</td>
<td>12 nm</td>
<td>10° Left</td>
<td>GSI</td>
<td>12 nm</td>
<td>45° Right</td>
<td>GSI</td>
<td>Get Preliminary Localizer Width, request adjustment if
necessary.</td>
</tr>
<tr class="odd">
<td>8</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/OFF</td>
<td>ARC</td>
<td>12 nm</td>
<td>10° Right</td>
<td>GSI</td>
<td>12 nm</td>
<td>45° Left</td>
<td>GSI</td>
<td>Recheck width</td>
</tr>
<tr class="even">
<td>9</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>ARC</td>
<td>10 nm</td>
<td>35° Left</td>
<td>GSI</td>
<td>10 nm</td>
<td>35° Right</td>
<td>GSI</td>
<td>OPTIMIZE WIDTH - Repeat 10-10 if needed</td>
</tr>
<tr class="odd">
<td>10</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>ARC</td>
<td>10 nm</td>
<td>35° Right</td>
<td>GSI</td>
<td>10 nm</td>
<td>35° Left</td>
<td>GSI</td>
<td>High Angle Clearance</td>
</tr>
</tbody>
</table>

**Figure 3**

**TLS Commissioning Profile**

(continued)

<table style="width:100%;">
<colgroup>
<col style="width: 4%" />
<col style="width: 9%" />
<col style="width: 9%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 5%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 5%" />
<col style="width: 0%" />
<col style="width: 22%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Step</strong></td>
<td><p><strong>Guidance TX</strong></p>
<p><strong>Config</strong></p>
<p><strong>(LOC/GS)</strong></p></td>
<td><p><strong>Ground</strong></p>
<p><strong>Xpndr</strong></p>
<p><strong>Config</strong></p></td>
<td><p><strong>Aircraft</strong></p>
<p><strong>Xpndr</strong></p>
<p><strong>Settings:</strong></p>
<p><strong>FI</strong></p>
<p><strong>Sel/Low</strong></p>
<p><strong>Pwr Sel</strong></p></td>
<td><p><strong>Type</strong></p>
<p><strong>Maneuver</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>Distance</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>AZ</strong></p></td>
<td><p><strong>Start</strong></p>
<p><strong>Alt</strong></p>
<p><strong>(MSL)</strong></p></td>
<td><p><strong>Stop</strong></p>
<p><strong>Distance</strong></p></td>
<td><p><strong>Stop</strong></p>
<p><strong>AZ</strong></p></td>
<td colspan="2"><p><strong>Stop</strong></p>
<p><strong>Alt</strong></p>
<p><strong>(MSL)</strong></p></td>
<td><strong>Remarks</strong></td>
</tr>
<tr class="even">
<td>11</td>
<td>LOW/ANY</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>ARC</td>
<td>18 nm</td>
<td>10° Left</td>
<td>4500 AGL</td>
<td>18 nm</td>
<td>10° Right</td>
<td>4500 AGL</td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td>12</td>
<td>LOW/ANY</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>ARC</td>
<td>18 nm</td>
<td>10° Right</td>
<td>4500 AGL</td>
<td>18 nm</td>
<td>10° Left</td>
<td>4500 AGL</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td>13</td>
<td>LOW/OFF</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>18 nm</td>
<td>C/L</td>
<td>GSI</td>
<td>T</td>
<td>C/L</td>
<td>GSI</td>
<td colspan="2">DISABLE G/S TO STOP ABORT ON LEAVING SV</td>
</tr>
<tr class="odd">
<td>14</td>
<td>LOW/ANY</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>ARC</td>
<td>10 nm</td>
<td>35° Right</td>
<td>GSI</td>
<td>10 nm</td>
<td>35° Left</td>
<td colspan="2">GSI</td>
<td>Restore Glide Slope. Get Preliminary Width</td>
</tr>
<tr class="even">
<td>15</td>
<td>ANY/LOW</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>LEVEL</td>
<td>10 nm</td>
<td>C/L</td>
<td>GSI</td>
<td>~ 3 nm</td>
<td>C/L</td>
<td colspan="2">GSI</td>
<td></td>
</tr>
<tr class="odd">
<td>16</td>
<td>ANY/LOW</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>LEVEL</td>
<td>10 nm</td>
<td>8° Right</td>
<td>GSI</td>
<td>~ 3 nm</td>
<td>8° Right</td>
<td colspan="2">GSI</td>
<td></td>
</tr>
<tr class="even">
<td>17</td>
<td>ANY/LOW</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>LEVEL</td>
<td>10 nm</td>
<td>8° Left</td>
<td>GSI</td>
<td>~ 3 nm</td>
<td>8°Left</td>
<td colspan="2">GSI</td>
<td></td>
</tr>
<tr class="odd">
<td>18</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>LEVEL</td>
<td>10 nm</td>
<td>C/L</td>
<td>GSI</td>
<td>~ 3 nm</td>
<td>C/L</td>
<td colspan="2">GSI</td>
<td>Optimize Width</td>
</tr>
<tr class="even">
<td>19</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>18 nm</td>
<td>C/L</td>
<td>Proc</td>
<td>SER</td>
<td>C/L</td>
<td colspan="2">50 AGL</td>
<td>Optimize Angle &amp; Alignment</td>
</tr>
<tr class="odd">
<td>20</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>FAF</td>
<td>C/L</td>
<td>Proc ++</td>
<td>SER</td>
<td>C/L</td>
<td colspan="2">50 AGL</td>
<td>Mean Width Above</td>
</tr>
<tr class="even">
<td>21</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>FAF</td>
<td>C/L</td>
<td>Proc --</td>
<td>SER</td>
<td>C/L</td>
<td colspan="2">50 AGL</td>
<td>Mean Width Below</td>
</tr>
<tr class="odd">
<td>22</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>FAF</td>
<td>C/L</td>
<td>LOW</td>
<td>T(C)</td>
<td>C/L</td>
<td colspan="2">LOW</td>
<td>Clearance Below Path. RESET CROSSPOINTER CALIBRATION</td>
</tr>
<tr class="even">
<td>23</td>
<td>Norm/Norm</td>
<td>STANDARD</td>
<td>ON/ON</td>
<td>APCH</td>
<td>FAF</td>
<td>150 μA Left</td>
<td>LOW</td>
<td>B</td>
<td>150 μA Left</td>
<td colspan="2">LOW</td>
<td>Clearance Below Path</td>
</tr>
<tr class="odd">
<td>24</td>
<td>Norm/Norm</td>
<td><p>P1/P3 "ON",</p>
<p>P2 "ON"</p>
<p>(STANDARD)</p></td>
<td>ON/ON</td>
<td>APCH</td>
<td>FAF</td>
<td>150 μA Right</td>
<td>LOW</td>
<td>B</td>
<td>150 μA Right</td>
<td colspan="2">LOW</td>
<td>Clearance Below Path</td>
</tr>
</tbody>
</table>