SPECIFICATION OF THE INVENTION

1. TITLE OF THE INVENTION

The method for generation of Mini Flight Director Symbol to provide enhanced navigation and guidance solution to the pilot of fighter aircraft.

2. FIELD OF THE INVENTION

The present invention relates to the navigation & guidance solution to the pilot of fighter aircraft in particular generation of Mini Flight Director Symbol by Flight Management Computer and display on Head up Display (HUD) system.

3. PRIOR ART AND DRAWBACKS OF PRIOR ART

HUD is the primary source of Navigation and Guidance information to the pilot along with outside world view. The Mission is planned on ground and the planned mission data is loaded to Flight Management computer. The pilot follows a designated flight path to reach to the destination Waypoint and the current flight information is presented to the pilot on HUD. There is no indication on HUD to inform to the pilot that the aircraft is deviated from the designated flight path and the aircraft is behind/ahead of the planned time of arrival to the destination. This can lead to the delayed response from the pilot in correcting the deviations with respect to designated flight path and planned time of arrival resulting in pilot not able to reach to the destination as per the planned mission.

4. AIM OF INVENTION

The main objective of this invention is to display mini flight director symbol on HUD to provide enhanced navigation and guidance solution to the pilot of fighter aircraft. Another objective of this invention is to indicate to the pilot on HUD how much the aircraft is deviated from the designated flight path. Another objective of this invention is to inform to the pilot how much the aircraft is ahead/ behind of the planned time of arrival to the destination.

5. SUMMARY OF INVENTION

Refer Figure 1:

This invention provides a method for enhanced navigation & guidance to the pilot by displaying a mini flight director symbol on Head Up Display (HUD) (4) of fighter aircraft. The Flight Management computer obtains the present position from on-board INGPS (Inertial Navigation Global Positioning System) sensor (2) and Mission Plan Data Base from Data Transfer System (1). The Flight Management computer (3) generates the mini flight director symbol and sends to HUD (4) for display. The mini flight director symbol is represented as a circle having radius of 5mR. The mini flight director symbol position on HUD is computed based on aircraft present position and the destination waypoint data (position, planned time of arrival, planned track and desired ground speed) from Mission Plan Data Base stored in non Non-volatile memory of the Flight Management computer. Flight management computer computes the cross track deviation (distance between the current track and the planned track) and the computed cross track deviation is represented on HUD in the horizontal direction with respect to FPM (Flight Path Marker)/CDM (Climb Dive Marker) symbol in manual and sequential navigation modes. The Flight Management computer computes the ahead or behind distance from destination waypoint along the planned track for a given planned time of arrival and the computed ahead or behind distance is represented on HUD in the vertical direction with respect to FPM/CDM symbol on HUD in sequential navigation mode.

6. BRIEF DESCRIPTIONS OF DRAWING

Figure 1 is the block diagram of an avionics system depicted in accordance with the present invention for providing the Mini Flight Director symbol on HUD.

Figure 2 illustrates the computation of various parameters for the display of Mini Flight Director Symbol

Figure 3 indicates the display of mini flight director symbol on HUD with all other symbols

7. DESCRIPTION OF THE INVENTION

Refer figure 1: The Mini Flight Director Symbol position is computed by the Flight Management computer (3) using aircraft present position and Mission Plan Data. The aircraft present position is obtained from on-board INGPS sensor (2). The Mission Plan Data is obtained from the Data transfer System (1) or it is fed by pilot through Up Front Control Panel (UFCP) (4). The Flight Management computer generates the mini flight director symbol and sends the display parameters to HUD (4) for display. The Mission Plan Data is stored in the non volatile memory of Flight Management computer. The Mission Plan Data consists of Waypoint Data and Flight Plan Data (set of waypoints in a sequence with parameters planned track, desired ground speed and planned time of arrival).

Flight Management computer uses the present position to compute the range and bearing to the destination waypoint position with respect to true north. There are two kinds of navigation modes namely sequential and manual mode of navigation. In manual navigation the mini flight director position on HUD represents the drift by which the aircraft deviates away from the designated flight path when the aircraft fly towards a destination waypoint and the deviation is represented in the horizontal direction. In the sequential mode of navigation the symbol moves in the horizontal and vertical direction. The movement of the symbol in the horizontal direction represents the drift by which the aircraft deviates away from the designated flight path when the aircraft fly towards a destination waypoint. The movement of the symbol in the vertical direction indicates the distance by which the aircraft leads or lags behind (ahead or behind) the destination waypoint at a given planned time of arrival and at a given desired ground speed.

(i) Mini Flight Director Symbol position computation in manual mode Refer figure 2: Present position of aircraft is obtained from INGPS. The flight management computer computes the range(R) and Bearing (Bearing angle) of the aircraft from the present position to destination waypoint. The flight management computer computes the cross track deviation (the deviation of the aircraft from the designated flight path in the horizontal direction). Cross Track Deviation = R x Sin (Bearing Angle) (1) The mini flight director symbol moves only in the horizontal direction in the manual navigation and the displacement from CDM/FPM is equal to the cross track deviation.

(ii) Mini Flight Director Symbol position computation in sequential mode Refer figure 2:
In sequential navigation mode flight plan is used for defining the flight path. For each flight leg the planned track, desired ground speed and planned time of arrival is fed when the flight plan is defined. In sequential navigation the flight management computer computes the range (R) and Bearing (Bearing angle) of the aircraft from the present position to destination waypoint. The computation for cross track deviation is same like in manual navigation and the cross track deviation of the aircraft decides the movement of the symbol in the horizontal direction.

The flight management computer computes the along track distance by using the formula:

Along Track distance = R x Cos (Bearing Angle) (2) The flight management computer uses the along track distance, desired ground speed (dgs) and the time remaining (time = planned time of arrival -current time) to reach the destination waypoint to compute the ahead or behind information in distance. The ahead or behind value is used for the movement of the symbol in the vertical direction.

Ahead or Behind = Along Track distance - (dgs x time) (3)

The displacement in the vertical direction is equal to the ahead or behind distance from FPM/CDM. Steps for computing the display position of mini flight director symbol on HUD

1. If the navigation mode is sequential, obtain the planned track (initial bearing angle), desired ground speed and planned time of arrival for the current flight leg from the Mission Planning Data Base at time t1.

2. If the navigation mode is manual, obtain the planned track from the initial position of the aircraft to the destination waypoint at time t1 by computing the range and initial bearing angle with respect to true north.

3. Compute the range (R) and bearing angle at present position of aircraft to the destination waypoint at time t2 (t2 > t1).

4. Compute the bearing angle (planned track - bearing angle at time t2).

5. Compute the cross track deviation by using the formula (1). If the computed cross track deviation is positive, the symbol will be positioned on the right side of FPM/CDM on HUD. If the computed cross track deviation is negative, the symbol will be positioned on the left side of FPM/CDM on HUD.

6. Compute the along track distance by using the formula (2). Compute the ahead or behind distance by using the formula (3). If the computed ahead or behind is positive, the symbol will be positioned above the FPM/CDM on HUD. If the computed ahead or behind is negative, the symbol will be positioned below the FPM/CDM on HUD.

7. Compute the horizontal display position of symbol on HUD from the cross track deviation with 1° per 1000 m. The vertical positioning of the symbol on HUD is obtained from the computed ahead or behind with a 1° per 1000 m.

Refer figure 3: The mini flight director symbol is displayed on HUD with respect to FPM/CDM. The symbol (1) is displayed above and to the left of FPM/CDM when the aircraft is drifted towards the left of designated track and it is ahead of planned time of arrival. The symbol (2) is displayed above and to the right of FPM/CDM when the aircraft is drifted towards the right of designated track and it is ahead of planned time of arrival. The symbol (3) is displayed below and to the right of FPM/CDM when the aircraft is flying behind the planned time of arrival and it is drifted towards right of designated track. The symbol (4) is displayed below and to the left of FPM/CDM when the aircraft is flying behind the planned time of arrival and it is drifted towards left of designated track. The symbol (5) will coincide with FPM

CLAIMS

We claim

1. The Method for providing enhanced navigation and guidance solution to the pilot by generation of Mini Flight Director by Flight Management Computer and by providing the display on Head up Display (HUD) of fighter aircraft.

2. The Method for the generation of Mini Flight Director as claimed in claiml provides solution in both manual navigation mode and sequential navigation mode.

3. The Method for the generation of Mini Flight Director as claimed in claiml provides the deviation of the aircraft from the designated flight path and is represented by moving the Mini Flight Director horizontally with respect to Flight Path Marker on HUD during Manual navigation.

4. The Method for the generation of Mini Flight Director as claimed in claiml provides the deviation of the aircraft from the designated flight path and is represented by moving the Mini Flight Director horizontally with respect to Flight Path Marker on HUD as well as how much the aircraft is ahead/ behind of the planned time of arrival to the destination and is represented by moving the Mini Flight Director vertically with respect to Flight Path Marker on HUD during Sequential navigation.