15 December 1965
ITEM NAME: LANDING CONTROL SET
TYPE: AN/MPN-11A, AN/MPN-11B, AN/MPN-11C, AN/MPN-11D
essential two-way communication between the ground
RELATION TO SIMILAR EQUIPMENT
and the aircraft. Special features incorporated in the
AN/MPN-11 are moving target indication (MTI), used
AN/CPN-4 and AN/MPN-11 models are all
with either or both radar sets to eliminate or attenuate
interchangeable with each other. The difference in
AN/CPN-4 and AN/MPN-11 models is variation in body
instantaneous direction-finding equipment, used in
styles, AN/CPN-4 has bolted trailer panels and
conjunction with the search radar set to locate aircraft in
AN/MPN-11 has riveted panels.
radio communication with the control center; circular
Landing Control Set AN/MPN-11A has a self-
reduce the echoes from rain or snow without
communications equipment as follows:
comparable loss of echo signals from the aircraft; and
Transceiver 185-4 for hf, AN/ARC-3 for vhf, and
operator controlled tilt of the search antenna.
AN/ARC-27 for uhf operation.
addition, all accessory equipment and power supplies
The AN/MPN-11B has a self-contained primary
are provided to permit the search radar set to function
power source, and uses Communication Equipment
as a completely independent unit.
AN/ART-13 and AN/ARR-15 for hf, AN/ARC-3 for vhf,
The 30-mile approach area must be under constant
and AN/ARC-27 for uhf operation.
surveillance so that approaching aircraft can be initially
The AN/MPN-11C uses an external Government-
located, identified, and directed into the final approach
furnished engine-generator in place of the normally used
position. To provide this 360-degree azimuth scan, the
Engine Generator PU-211/G; a 7-1/2 ton electric Air
power-drive antenna is mounted on a rotating base.
Conditioner HD-237/MPN-11C is used in place of the
This antenna concentrates the radio-frequency energy
Diesel Air Conditioner HD-78/G normally used by other
into a high, narrow radiation pattern, to consistently
models; a Power Distribution Panel SB-503/MPN-11C is
return echoes strong enough for good presentation on
used to control an external engine-generator and electric
the search indicators.
air conditioner; a 28 volt rectifier power supply (Power
The direction-finding equipment may use any one of
Supply PP-1383/MPN-1K) is furnished in place of Motor-
the high-frequency, very-high-frequency, or ultra-high-
Generator PU220/GPN, used by other models of the
frequency communication channels to locate and
AN/MPN-11; and the AN/MPN-11C does not require the
identify aircraft communicating with the radar set.
remote line drives, remote line driver power supplies, or
When the direction-finder set is switched on at the
search indicator panel, the radio-frequency carrier
The AN/MPN-11D is similar to the AN/MPN-11C
radiated from the aircraft is used to generate a strobe of
except that it incorporates AFC control of the S and X
light on the plan position indicator (PPI) oscilloscope to
indicate aircraft direction. When a high-frequency, very-
provisions and does not include Interconnecting Group
high-frequency or ultra-high-frequency channel is
AN/GPA-41. Subsequent to these circuit and equipment
selected o. the communications control panel at a
changes, this item is still functionally interchangeable
control position, the direction finding set is automatically
tuned to the same frequency.
The precision radar equipment incorporates a single
X-band transmitter, pulsing alternately through separate
azimuth and elevation antennas, to track aircraft down
Frequency Range: 2780 to 2820 mc
the glidepath during the final approach.
Power Output: 600 kw (peak)
The consistent reliable range of the precision equipment
Pulse Repetition Rate: 1500 pps
is approximately 10 nautical miles, slant range, for small
Range: 20 to 30 mi, depending on type
aircraft flying within an elevation angle of 6 degrees.
of aircraft tracked.
The electronically traced range marks, occurring at I-
nautical-mile intervals, are spaced logarithmically on the
Azimuth: 360 deg
plan-position indicator, so that the most critical first mile
Elevation: 1/2 to 45 deg
of the visual display occupies a greater distance along
the indicator sweep than the less critical succeeding
Azimuth: 1 deg
miles. This has the effect of expanding that portion of
Range: 4 pct
both displays representing the area in which the aircraft
actually contacts the runway.