SPECIFICATION OF THE INVENTION

1. TITLE OF THE INVENTION

A novel method for updating the time schedule of Automatic Flight Plan Navigation of an Aircraft

2. FIELD OF THE INVENTION

The present invention relates to aircraft navigation, in particular about the automatic flight plan navigation of an aircraft. The invention, relates to a method of adding/ subtracting delay time to the active flight plan schedule of an aircraft.

3. PRIOR ART AND DRAWBACKS OF PRIOR ART

The Mission plan, including the Flight plans are prepared and loaded to Flight Management Computer (103) on ground. During the flight the pilot activate and follow a flight plan to navigate the aircraft to destination. The Flight Management Computer (103) computes the range, bearing, Plan Time of Arrival (PTA) to the destination waypoint and Desired Calibrated Air Speed (DCAS) to reach destination waypoint on time. These information along with present position of the flight is displayed to the pilot on Head Up Display (HUD) (104) by Flight Management Computer (103).

The flight plan schedules can only be modified on Ground station and reschedule of the flight plan is not possible during the flight. Hence, in case, the flight plan schedule is to be proponed or postponed during flight, the Flight Management Computer (103) cannot correctly predict the PTA & DCAS required to reach the destination waypoint on time.

4. AIM OF INVENTION

The main objective of this invention is to provide the pilot the provision of introducing delay/ advance time to flight plan schedule during the flight and update the Plan Time of Arrival (PTA) for each waypoint of the flight plan.

Further objective of this invention is to compute and display the Desired Calibrated Air Speed (DCAS) to reach the destination waypoint on time based on updated PTA.

5. SUMMARY OF INVENTION

This present invention provides the provision to modify the time schedule of the Active flight Plan during flight. By means of Up-Front Control Panel (105) pilot can enable the present method and feed +/- ve delay time to Flight Management Computer (103). Flight Management Computer (103) invokes the Flight Plan Computation Module (106) to re-computes the Plan Time of Arrival (PTA) of each destination waypoint of the flight plan based on the entered delay time. The Flight Plan Computation Module (106) receives position, velocity and time data from GPS and destination waypoint data including PTA from Non-Volatile RAM (NVRAM). The module computes Desired Ground Speed (DGS) and Desired Calibrated Air Speed (DCAS) to reach the destination waypoint on time utilizing the received data. The Flight Management Computer (103) generates symbologies for the display of PTA to the Destination waypoint, DCAS etc. on Head UP Display (HUD) (104) for navigation guidance in automatic flight plan navigation. The entered delay time is also displayed on the HUD (104) for indication to the pilot.

6. BRIEF DESCRIPTIONS OF DRAWING

Figure 1 is the block diagram of the present invention for introducing the delay time into automatic flight plan navigation time schedule by means of Flight Management Computer.

Figure 2 illustrates the flow chart for introducing the delay/ advance time into flight plan
time schedule and computation of PTA and DCAS.

7. DESCRIPTION OF THE INVENTION

The present invention provides the pilot with a provision to introduce positive/ negative delay time to the Flight Plan time schedule during flight, using Up Front Control Panel (UFCP) (105) of the Aircraft. The Flight Plans and waypoints are loaded to Flight Management Computer (103) from Data Transfer Unit (101) and stored in Non-Volatile RAM (NVRAM) (110) of the Flight Management Computer (103). If the present method is selected in flight and delay time is entered through UFCP, the Flight Management Computer (103) receives selected delay time in Delay module (107) and invokesFlight plan computation module (106). The Flight plan computation module (106) computes the Plan Time of Arrival (PTA) and Desired Calibrated Air Speed (DCAS) as per the modified flight plan time schedule.

The Flight Management Computer (103) is interfaced with UFCP (105) and receives key press data. UFCP (105) provides option for selection of present method and enter +/-ve delay time through data entry keys. The Delay Module (107) of the Flight Management Computer (103) receives data entry keys from UFCP (105) and determines the entered +/-ve delay time value for active Flight Plan during flight.

The Flight Management Computer (103) is interfaced with Global Positioning System (GPS) (102) and receives present position data such as current latitude, longitude, elevation, ground speed of the Aircraft and the current time.

The Flight plan computation module (106) consists of PTA module (108)& DCAS module (109). The PTA module (108) receives delay time from Delay module (107), computesPTA for all destination waypoints of the active flight plan, as per modified time schedule and stores the updated PTA data of active flight plan in NVRAM (110).

The DCAS module (109) receives present position, horizontal component of ground speed (Vg) and current time from GPS (102), Calibrated .Air Speed (CAS), Air Density Ratio from Flight Management Computer (103) and destination waypoint data including PTA from NVRAM (110). The module computes desired CAS (DCAS) to reach the destination waypoint on time using the data received from GPS (102) and NVRAM (110).

Different steps involved in updating time schedule of the flight plan and computation of navigation parameters (PTA and DCAS) as per updated time schedule is depicted in Figure 2.

In the starting, Step 201, the Flight plan computation module (106) get Flight Plan and waypoint data from NVRAM (110) and computes the Range (R) and Bearing (Bearing angle) of the aircraft present position to destination waypoint. The Flight plan computation module (106) computes the along track distance (horizontal range from Aircraft to destination waypoint) as follows:

Along track distance = R x Cos (Bearing Angle) (1)
In Step 202, the Flight Management Computer (103) check if method for re¬schedule of the Active Flight plan is activated and if activated, follows Step 204 to Step 206, otherwise follow Step 203.

In Step 204, the Delay module (107) receives +/-ve delay time from UFCP (105) and determines the delay time value.

In Step 205, the PTA module (108) re-computes PTA with entered delay time as follows:

PTA of destination waypoint after introducing the Delay Time
= PTA +/- Delay Time. (2)

In Step 206, The DCAS module (109) computes Desired Ground Speed (DGS) and Desired Calibrated Air Speed (DCAS) to reach destination waypoint on time, based

on received Plan Time of Arrival (PTA) of the destination waypoint data from NVRAM (110) as follows:

DGS = along track distance / PTA of destination waypoint (3)

DCAS = CAS + (DGS - Vg) * SQRT(Air density ratio) (4)
In Step 203, The DCAS module (109) computes desired Calibrated Air Speed (DCAS) as in step 206, without any modification of PTA and without reschedule of the Flight Plan.

In Step 207, the Flight Management Computer (103) generates display of the computed navigation information for flight plan navigation, such as PTA, DCAS for Head Up Display (HUD) (104).

In the present invention, the computed navigation and guidance information such as PTA, DCAS is displayed on Head Up Display (HUD) (104) for automatic Flight Plan navigation aid to Pilot. The delay time entered for reschedule of the Flight plan is also displayed on HUD (104) by the Flight Management Computer (103).

Figure 1: Block Diagram of method for introducing the delay time into automatic flight plan navigation time schedule by means of Flight Management Computer.

CLAIMS

We claim

1. A novel method for updating the time schedule of Automatic Flight plan navigation for an Aircraft using Flight Management Computer (103) and Up Front Control Panel (104).

2. The method in claimed in 1, where in the +/-ve delay time (delay/ advance) for the time schedule of the flight plan is entered to Flight Management Computer (103) by pilot using Up-Front Control Panel (104).

3. The method in claimed in 1, where in, the Flight Plan Computation module (106) of Flight Management Computer (103) re-computes the Plan Time of Arrival (PTA) for each waypoint of the active Flight Plan, based on +/-ve delay time entered by pilot through UFCP (104).

4. The method in claimed in 1, where in, the Flight Plan Computation module (106) of Flight Management Computer (103) re-computes the Desired Calibrated Airspeed (DCAS) based on the updated PTA of the destination waypoint.