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
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
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
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
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.