JP2701742B2 - Aircraft direction guidance method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aircraft azimuth guidance system, and more particularly to an aircraft azimuth guidance method and apparatus at an airport where obstacles are present around the aircraft.

[0002]

2. Description of the Related Art As is well known, an ILS localizer controller is used.
The maximum offset angle is specified as 3 °, but in a basin-like airport where obstacles such as mountains are intermittently present, obstacles ahead can be cleared from the phase center of the ILS localizer antenna on the runway. The azimuth often exceeds the offset angle. The folding line direction guidance device is a device for guiding the aircraft in a folding line shape in such a basin-like airport to avoid obstacles and safely guide the aircraft to the runway by instrument landing.

FIG. 7 shows an example of such a linear azimuth direction guiding apparatus that has been conventionally proposed. This is a microwave landing device (MLS) on-board device described in Japanese Patent Application Laid-Open No. 2-287900, but is obtained by using a GPS (global positioning system) receiver as a distance measuring device. It is an object of the present invention to enable approach and landing by complicated MLS such as approaching a curved line or a curved line using precise distance data. Hereinafter, an outline of this conventional device will be described.

In FIG. 7, an MLS on-board device basically comprises an antenna 101, an MLS receiver 102, a navigation computer 103, a navigation indicator 104, an autopilot 105, a GPS antenna 106, and a GPS receiver 107. Is done.

[0005] The MLS signal received by the antenna 101 is received and processed by the MLS receiver 102, and is converted into various data such as angle measurement values (azimuth and elevation) and antenna positions of the ground station, and is used as a navigation computer. 103.

On the other hand, the GPS signal received by the GPS antenna 106 is received and processed by the GPS receiver 107, the position of the receiving point (aircraft) is measured, and the measured position data is inputted in advance. The distance from the aircraft to the landing point is calculated based on the position data of the landing point on the runway, and the calculated distance is supplied to the navigation computer 103.

The navigation computer 103 includes an MLS receiver 102
Calculates the position of own aircraft based on the data (azimuth measurement value, elevation measurement value, terrestrial transmission antenna position, azimuth and elevation angle of approach route, etc.) and distance data from GPS receiver 107 Then, a deviation from a predetermined approach route is calculated. This shift information is divided into horizontal and vertical components with respect to the predetermined route and the distance to the landing point, and is displayed on the navigation display 104.

The navigation indicator 104 includes a commonly used HSI (horizontal status indicator) and EHSI (Electronic Ho
rizontal Situation Indication: an electronic horizontal status indicator capable of displaying in a map format is used.

In the case of autopilot, the autopilot 105 receives the deviation data and the distance data from the navigation computer 103, and controls the steering angle and auxiliary of the aircraft necessary for automatic piloting of the aircraft. Calculate the control signals required to control the wing.

[0010]

However, in the above-mentioned conventional folding line approach system of the MLS on-board device, the size of the folding line approach system increases because the MLS ground station and a plurality of GPS satellites are used in combination. There is a problem that. Further, when the satellite is out of order, the response is complicated, and during that time, there is also a problem that a broken line cannot be entered.

Also, in addition to the MLS receiver, it is necessary to equip a GPS receiver, a navigation computer, and an autopilot on the aircraft, and these are all expensive devices.
There is also a problem that the price of the folding line approach system becomes high.

Therefore, instead of the GPS, a DM is used as a means for acquiring precise distance information required for landing guidance by the MLS.
It is conceivable to use E / P.

However, the approach / landing system using the DME / P has a degree of accuracy equivalent to that of a normal DME at a distance of more than 7 nautical miles and cannot enter a curved line or a curved line. When mixed with direct waves, the distance accuracy is reduced, so that there is a problem that an error in entering the folding line increases. In addition, expensive D
The need for an ME / P interrogator and an expensive DME / P transponder on the ground is also a problem in terms of increasing the cost of the system.

The present invention has been made in view of such conventional problems, and has as its object to provide an aircraft direction guidance method and apparatus capable of performing safe instrument landing guidance with a simple and small-scale configuration. Is to do.

[0015]

The azimuth guidance method according to the present invention is applied to the azimuth guidance of an aircraft at an airport having at least an obstacle in front of the runway. When the aircraft that forms the course and enters along the initial approach guidance course passes the obstacle avoidance point, the direction of the approach guidance course is shifted to the centerline of the runway at the angular velocity determined based on the ground speed of the aircraft. When the aircraft that scans in accordance with the azimuth scan of this approach guidance course reaches the center extension of the runway,
A final approach guidance course is formed by matching the direction of the approach guidance course with the direction of the centerline of the runway.

The azimuth guidance device according to the present invention is disposed at an avoidance point of an obstacle, first detection means for detecting that an aircraft has passed near the sky, and disposed on a central extension line in front of the runway. Second detection means for detecting that the aircraft has passed over the sky, course generation means arranged at the end of the runway to form an approach guidance course for the aircraft, and the approach guidance course from the initial approach guidance course as described above. Azimuth scanning control means for scanning up to the final approach guidance course.

[0017]

[Function] The aircraft first approaches the obstacle by avoiding obstacles along the initial approach guidance course, and then the direction of the approach guidance course is scanned, so that the aircraft gradually reaches the final approach on the center extension of the runway. When approaching the course and reaching the final approach course, make a regular instrument approach and land on the runway.

In the ILS localizer, the regular course is set so that the maximum offset angle from the extension of the center of the runway is within 3 °. For this reason, when there is an obstacle around the runway intermittently exceeding the maximum offset angle, the final approach guidance course by the ILS localizer is directed toward the obstacle ahead of the runway localizer antenna phase center. Formed.

On the other hand, the initial approach guidance course is formed so as to extend from the phase center of the localizer antenna to a space in a direction where the obstacle is cut off. When an initial approach aircraft is detected, the direction of the initial approach guidance course is controlled so as to gradually change toward the centerline of the runway in accordance with the ground speed of the aircraft.

As a result, the instrument enters from the direction in which the obstacle ahead of the runway is cut off, enters the instrument in a folded line inside the obstacle, and rides on the regular ILS localizer course on the extension line of the center of the runway. You will be able to enter.

The ILS localizer course is composed of a directional pattern and a clear run pattern whose carrier frequencies are slightly different from each other and whose carrier wave amplitude ratios differ by 13 dB or more on the course sector. That is, it is formed by the dual frequency method. This is because the influence of the reflected wave from the obstacle due to the clear run pattern on the localizer course is suppressed by the capture effect generated by the linear detection characteristic of the onboard ILS receiver.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram showing an embodiment of a folding line direction guiding apparatus according to the present invention, and FIG. 2 is a schematic bird's-eye view of a basin-like airport showing an example in which this embodiment is specifically applied. FIG.

Referring to FIG. 1, the folding azimuth direction guiding apparatus of the present embodiment includes a dual frequency localizer course generating apparatus, a scanning controller 6 for performing azimuth scanning, and a first sensor 7 for detecting an initial approach aircraft. And a second sensor 8 for detecting a final approach aircraft
And is basically composed of The first sensor 7 includes a transmission system including a transmitter 20a and a transmission antenna 21a, a reception system including a reception antenna 23a and a detection circuit 25a,
Consists of The second sensor 8 includes a transmission system including a transmitter 20b and a transmission antenna 21b, and a reception antenna 23.
b and a receiving system comprising a detection circuit 25b.

As shown in FIG. 2, the dual-frequency localizer course generator is installed on the extension of the end of the approach runway 11, and emits a beam to form an approach course of the aircraft. ing. The first sensor 7 is disposed between obstacles 10a and 10b intermittently present in front of the runway 11,
The second sensor 8 is disposed on an extension of the front end of the runway 11.

The dual frequency localizer course generator Figure 3 is a detailed block diagram of a dual frequency localizer course generator of this embodiment, Figure 4 shows a radio wave field strength pattern emitted from the dual frequency localizer course generator It is a graph.

As shown in FIG. 3, the dual-frequency localizer course generator includes a directional transmitter 1, a clearance transmitter 2, a power distributor 3, and antenna elements 5a.
5b.

The directional transmitter 1 and the clearance transmitter 2 of the dual-frequency localizer course generator have I
Using a high-frequency signal (f ₀ ± Δf) slightly different from 5 KHz to 14 KHz with respect to the nominal localizer frequency f ₀ specified by the CAO Annex 10, the directional carrier signal 18a and the clearance carrier signal 18b are respectively used. The sideband signal 19a and the clearance subband signal 19b are output. The carrier signals 18a and 18b are generated by performing amplitude modulation (modulation degree of about 20%) on the high-frequency signal with the same phase of 90 Hz component and 150 Hz component.
The sub-band signals 19a and 19b are generated by balance-modulating one sideband component (90 Hz or 150 Hz) so as to have an opposite phase to that of the carrier signal. The modulated signals (90 Hz, 150 Hz) of these carrier signals and sideband signals are synchronized by a 30 Hz synchronization signal 17.

The directional transmitter 1 in the present embodiment generates a high-frequency signal of f ₀ +4 KHz, and the clearance transmitter 2 generates a high-frequency signal of f ₀ -4 KHz.

Power Divider 3 The power divider 3 supplies high frequency power to the antenna elements 5a... 5x via the phase shifters 4a. At that time, the power distributor 3 forms the electric field intensity pattern shown in FIG. 4, that is, the directional carrier radiation pattern 28, the directional sideband radiation pattern 29, the clearance carrier radiation pattern 30, and the clearance sideband radiation pattern 31. As described above, the directional carrier signal 18a, the clearance carrier signal 18b, the directional sideband signal 19a,
The clearance sideband signals 19b are distributed and combined at an appropriate current ratio.

As shown in FIG. 4, the carrier level ratio 32 between the directional carrier emission pattern 28 and the clearance carrier emission pattern 30 is set to be 13 dB or more within the range of the course sector. With this setting, the influence of the beam reflection from the obstacles 10a, 10b,... On the initial approach guidance course 12 is sufficiently reduced by the capture effect generated by the characteristics of the linear detector of the onboard ILS receiver.

Antenna elements 5a ... 5x for emitting beams
As shown in FIG. 3, 12 pairs of antenna element groups are arranged at equal intervals of 0.6 wavelength symmetrically with respect to an array antenna phase center point 16 on an extension of the runway center line 15 as shown in FIG. . That is, a pair of antenna elements 5l and 5m are set at the center, and the antenna elements 5a and 5
Twelve antenna elements up to x are arranged at equal intervals.

4x for realizing azimuth scanning are provided corresponding to the antenna elements 5a to 5x, respectively. The phase shifters 4l to 4a and the phase shifters 4m to 4x are arranged in opposite directions to each other. At the step angle Δφ.

Scan Controller 6 FIG. 5 is a block diagram showing a detailed configuration of the scan controller 6 in this embodiment. The scanning controller 6 includes a delay circuit 3
8, oscillator 34, frequency dividers 35a and 35b, timing circuit 40, step counter 44, ROM (Read Only
Memory) 45a... 45x, adders 46a... 46x, and correction data 47a.

The timing circuit 40 uses the initial approach detection signal 26a from the first sensor 7 as a start pulse signal, the final approach detection signal 26b from the second sensor 8 as a stop pulse signal, and the final approach detection signal 26b. Are delayed as appropriate by a delay circuit 38 and input as reset signals 39. Delay circuit 38
After receiving the final approach aircraft detection signal 26b,
Has a function of calculating and delaying the time required for landing on the runway 11 in advance. This delay signal 39 is used as a reset signal of the scanning controller 6.

When the start pulse signal 26a, the stop pulse signal 26b, and the reset signal 39 are input, the timing circuit 40 adjusts the timing according to the reference clock signal 36, and the start / stop signal 41, the up /
The down signal 42 and the reset signal 43 are output to the step counter 44.

The clock pulse generated by the oscillator 34 is frequency-divided by a frequency divider 35a to a required frequency, and is input to a timing circuit 40 as a reference clock signal 36. The reference clock signal 36 is further frequency-divided by the frequency divider 35 b and input to the step counter 44 as the step clock signal 37.

The phase shift amounts required for azimuth scanning are written in the ROMs 45a... 45x in advance. That is, the distance of each antenna element from the array antenna phase center 16, the initial approach azimuth φ ₁ , the step angle Δφ, and the final approach azimuth φ _n
The phase difference from the array antenna phase center 16 is calculated in advance from each set value of the above, and written in the ROM 45a... 45x as a phase data code quantized to an appropriate number of bits.

The ROMs 45a... 45x output phase data according to the address data from the step counter 44. These phase data are added by the correction data 47a... 47x and the adders 46a.
After the inherent phase difference due to the cumulative error of the power supply path length up to 5x is corrected, the signal is supplied to the phase shifters 4a to 4x as phase shifter control signals 27a to 27x.

First Sensor 7 The first sensor 7 includes, as shown in FIG.
b. A transmission system (transmitter 20a, transmission antenna 21) that is installed near the position where the trace is cut off or near the top of a relatively low obstacle where radio waves are not completely shielded, and radiates radio waves toward the sky
a) and a receiving system (receiving antenna 23a, detection circuit 25a) for receiving a reflected wave from the aircraft 9 passing over the first sensor 7.

In this embodiment, the current ILS outer marker transmitter is used as the transmitter 20a, and the transmitting antenna 21a is used.
The current ILS outer marker antenna is used as a. That is, the transmitting antenna 21a radiates the amplitude-modulated carrier wave from the transmitter 20a toward the sky where the obstacles 10a, 10b,... Are cut off, and forms the first sensor radiation pattern 22a shown in FIG.

The reflected wave from the aircraft 9 is received by a high-gain receiving antenna 23a, and a received signal 24a is
5a. The detection circuit 25a receives the reception signal 24a
When it is determined that the vehicle is an approach aircraft based on the amplitude and the duration, an initial approach aircraft detection signal 26a is generated and supplied to the scanning controller 6.

The second sensor 8 and the second sensor 8, as shown in FIG. 2, is installed in a suitable position on the runway center line 15 extension inside the obstacle 10a, performs radio emission towards the sky Transmission system (transmitter 2
0b, transmitting antenna 21b) and a receiving system (receiving antenna 23) that receives a reflected wave from aircraft 9 passing over it.
b, detection circuit 25b).

In this embodiment, the current ILS middle marker transmitter is used as the transmitter 20b, and the transmitting antenna 21b is used.
The current ILS middle marker antenna is used as b. That is, the transmitting antenna 21b radiates the amplitude-modulated carrier wave from the transmitter 20b to a position directly above the intersection of the bent line approaching guidance course 13 and the final approaching guidance course 14, and emits the second sensor radiation shown in FIG. The pattern 22b is formed.

The reflected wave from the aircraft 9 is received by the high gain receiving antenna 23b, and the received signal 24b is detected by the detection circuit 2b.
5b. The detection circuit 25b receives the reception signal 24b
Is determined to be an approach aircraft based on the amplitude and the duration, a final approach aircraft detection signal 26b is generated and supplied to the scanning controller 6.

The detection circuits 25a and 25b used in the first sensor 7 and the second sensor 8 have the same configuration, and the configuration will be described.

The detection circuit 25a and 25b Figure 6 is a circuit diagram showing a detailed configuration of the detection circuit used in the first sensor and the second sensor in the present embodiment.

Referring to FIG.
a (or 23b) outputs the received signal 24a (or 24b).
b) is subjected to high-frequency amplification by an RF amplifier 48, then converted into an intermediate frequency signal by a frequency converter 49, and
Through the intermediate frequency amplifier 51. Further, after being detected by the detector 52, it is digitized by the AD converter 53 and becomes one input of the level comparator 55. Also,
The reference voltage is digitized by the AD converter 54 and becomes the other input of the level comparator 55.

The level comparator 55 performs a level comparison operation of both inputs in accordance with the clock 57 from the clock pulse generator 56, and when it detects an approaching machine, gives the detection signal to one input of a gate circuit 58 to switch the gate. Let it open. As a result, the gate circuit 58 supplies the clock 57 from the clock pulse generator 56 to the counter 59 while the detection signal from the level comparator 55 exists. This allows
The counter 59 counts the number of clock pulses and supplies the counted number to one input of the time comparator 60.

The time comparator 60 compares the set time given to the other input with the output of the counter 59, ie, the detection continuation time. If the detection continuation time is longer than the set time, it is determined that the vehicle is passing through the approaching machine. The flip-flop 61 is set. As a result, the initial approach aircraft detection signal 26a (or the final approach aircraft detection signal 26a) is output from the flip-flop 61.
b) is output.

The output of the level comparator 55 after passing through the aircraft 9 closes the gate circuit 58 and is supplied to the flip-flop 61 as a reset signal 62.

Assuming that the ground speed when the aircraft enters the ILS is about 230 Km / H for a large aircraft and about 90 Km / H for a small aircraft, the detection duration is about 1.10 for a large aircraft with a total length of about 71 m. One second is about 0.44 seconds for a small aircraft with a total length of about 11 meters. Therefore, the set time of the time comparator 60 may be set to, for example, about 0.4 seconds.

Setting of azimuth scanning speed Next, a method of setting the azimuth scanning speed in this embodiment will be described.

In FIG. 2, an array antenna phase center 1
The distance from the first sensor 7 to the first sensor 7 is D ₁ (m), the distance to the second sensor 8 is D _n (m), and the initial approach azimuth is φ ₁ (de).
g), the ground speed of the aircraft at the time of entering V (m / s), when the first sensor 7 and connecting it distance or polygonal line entry distance the second sensor 8 in a straight line and D _B (m), polygonal line entry The time t _B (S) is given by equation (1).

[0055] _{t B (S) = D B} (m) / V (m / s) = √ (D 1 2 + Dn 2 -2D 1 D 2 cosφ) / V ··· (1) Thus, the scan controller 6 , Ie, the azimuth change V _s (deg / s) per second is given by equation (2).

V _s (deg / s) = φ ₁ (deg) / t _B (s) (2) Here, as one embodiment, D ₁ = 10767 m (= 5.81)
NM), D _n = 4350 m (= 2.35 NM), φ ₁ = 1
0 ゜, average ground speed at landing approach of large aircraft V = 23
Assuming that 0 km / h = 63.9 m / sec, the folding line entry time t _B (s) is about 102 seconds and the azimuth angle change V per second is V
_s (deg / s) is about 0.1 °.

It is apparent that the present invention can be easily used not only for entering a folding line but also for starting a folding line or returning to a folding line if the detection method and the scanning control direction are all reversed.

[0058]

As described above, according to the azimuth guidance method and apparatus of the present invention, the aircraft enters the vehicle while avoiding obstacles along the initial approach guidance course, and then the azimuth of the approach guidance course is changed. By being scanned, the vehicle gradually approaches the final approach course on the central extension of the runway, and upon reaching the final approach course, lands on the runway with a regular instrument approach. For this reason, even in a basin-like airport in which obstacles such as mountains exist in front of the runway, the aircraft can be guided in a folded line avoiding those obstacles and can be safely landed.

In the azimuth guidance device according to the present invention, the first detection means, the second detection means, the course generation means and the azimuth control means need only be installed on the ground, and no special function is required. In particular, if a current ILS on-board receiver and an ILS localizer ground station are used, the system can be easily configured as a small-scale system. It is very cheap in terms of equipment costs and maintenance costs.

Further, by using the ILS dual-frequency localizer, a dual-frequency localizer course utilizing the capture effect can be formed from a predetermined position behind the runway stop end in a direction that can avoid an obstacle in front of the runway. Even in basin-like airports where obstacles such as mountains are intermittently present, aircraft can be safely guided on the initial approach course. Further, the azimuth scanning of the dual-frequency localizer course is controlled at an angular velocity corresponding to the ground speed of the aircraft from near the sky above the first detecting means to near the sky above the second detecting means, that is, on the regular ILS localizer course. The aircraft can be reliably guided in the form of a broken line from the avoided space to the runway extension line.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an azimuth guidance device according to the present invention.

FIG. 2 is a schematic bird's-eye view of a basin-like airport showing an example in which the present embodiment is specifically applied.

FIG. 3 is a detailed block diagram of a dual-frequency localizer course generator in the present embodiment.

FIG. 4 is a graph showing an electric field intensity pattern of a radio wave emitted from the dual-frequency localizer course generator.

FIG. 5 is a block diagram showing a detailed configuration of a scanning controller 6 in the present embodiment.

FIG. 6 is a circuit diagram showing a detailed configuration of a detection circuit used for a first sensor and a second sensor in the present embodiment.

FIG. 7 is a block diagram showing a configuration of a conventional azimuth guidance device (MLS on-board device).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Directional transmitter 2 Clearance transmitter 3 Power distributor 4a ... 4x Phase shifter 5a ... 5x Antenna element 6 Scan controller 7 First sensor 8 Second sensor 9 Aircraft 10a, 10b Obstacle 11 Runway 12 Initial approach guidance Course 13 Folding line approach guidance course 14 Final approach guidance course 15 Runway centerline 16 Array antenna phase center 17 Synchronization signal 18a, 18b Carrier signal 19a, 19b Sideband signal 20a, 20b Transmitter 21a, 21b Transmitting antenna 22a, 22b Sensor radiation Pattern 23a, 23b Receiving antenna 24a, 24b Receiving signal 25a, 25b Detection circuit 26a Initial approach aircraft detection signal 26b Final approach aircraft detection signal 27a ... 27x Phase shifter control signal 28 Directional carrier radiation pattern 29 Directional sideband radiation pattern 30 Chestnut Lance carrier radiation pattern 31 Clearance sideband radiation pattern 32 Carrier level ratio 33a ... 33n Dual frequency localizer course 34 Oscillator 35a, 35b frequency divider 36 Reference clock signal 37 Step clock signal 38 Delay circuit 39 Reset signal 40 Timing circuit 41 Start / Stop Signal 42 Up / Down signal 43 Reset signal 44 Step counter 45a ... 45x ROM 46a ... 46x Adder 47a ... 47x Correction data 48 RF amplifier 49 Frequency converter 50 Filter 51 Intermediate frequency amplifier 52 Detector 53,54 A / D converter 55 level comparator 56 clock pulse generator 57 the clock 58 gate circuit 59 the counter 60 hours comparator 61 flip-flop phi ₁ initial approach azimuth Δφ step angle phi _n final ary Azimuth

Claims (5)

(57) [Claims] 1. A method for guiding an aircraft at an airport having an obstacle at least in front of a runway, comprising: a dual-frequency instrument landing device localizer (hereinafter, ILS) for initial approach guidance at an azimuth angle avoiding the obstacle. Dual frequency localizer) initial course formation step to generate a course;
ILS dual frequency localizer for approach guidance When an aircraft that has entered along the ILS dual frequency localizer course passes an obstacle avoidance point, the ILS dual frequency localizer for approach guidance at an angular velocity determined based on the ground speed of the aircraft. An azimuth scanning step of scanning an azimuth of a course toward the center line of the runway, and the aircraft that has entered according to the azimuth scan of the ILS dual-frequency localizer course for approach guidance reaches a center extension of the runway. Forming a final course for stopping the azimuth scanning by matching the direction of the ILS dual frequency localizer course for the approach guidance with the direction of the center line of the runway to form an ILS dual frequency localizer course for the final approach guidance. And an azimuth guidance method for an aircraft. 2. The step of forming a final course includes the step of detecting that the aircraft has reached the center extension of the runway, and the time required for the aircraft to land on the runway from the time of the detection. 2. The azimuth guidance method according to claim 1, further comprising: matching an azimuth of an ILS dual-frequency localizer course for the approach guidance with an azimuth of a centerline of the runway. 3. Following the final course forming step,
ILS for guiding the approach after the aircraft has landed
3. The azimuth guidance method according to claim 1, further comprising the step of returning the dual-frequency localizer course to the azimuth of the initial approach guidance course. 4. An aircraft direction guidance device at an airport where an obstacle exists at least in front of the runway, wherein the first detection means is arranged at an avoidance point of the obstacle and detects that the aircraft has passed near the sky. Second detection means disposed on a central extension line in front of the runway to detect that the aircraft has passed over the sky, and an ILS disposed at the end of the runway for guiding the approach of the aircraft A course generating means for forming a dual-frequency localizer course;
An ILS dual-frequency localizer for the approach guidance is formed at an initial azimuth angle avoiding the obstacle, and an angular velocity determined based on a ground speed of the aircraft when the aircraft is detected by the first detection means. Scanning the azimuth of the ILS dual-frequency localizer course for the approach guidance toward the center line of the runway, and when the second detection means detects the aircraft, the ILS for the approach guidance
An azimuth guidance device for an aircraft, comprising: azimuth scanning control means for causing the azimuth of the dual-frequency localizer course to coincide with the azimuth of the center line of the runway. 5. The azimuth scanning control means includes arithmetic means for calculating an estimated landing time required from when the second detection means detects the aircraft to when the aircraft lands on the runway, The azimuth guidance device according to claim 4, wherein the ILS dual-frequency localizer for the approach guidance is returned to the initial azimuth angle when the estimated landing time has elapsed.