Apparatus, method and system relating to aircraft systems

1. A method for controlling flight of an aircraft system, the method comprising:

deriving a two-dimensional liability map using mapping data related to one or more ground hazard categories, wherein each ground hazard category is associated with a type of hazard on a ground surface, wherein the two-dimensional liability map comprises a plurality of risk liability values (L1) associated with the one or more ground hazard categories; and

using the liability map to control one or more parameters for controlling flight of the aircraft system, wherein deriving the two-dimensional liability map comprises:

dividing a ground surface region of interest into a discretized two-dimensional grid;

for each element of the grid, deriving an amount of area of that element that falls within a relevant ground hazard category;

for each ground hazard category, estimating a consequence value (C Y ) based on a size of the aircraft system; and

for each element of the grid, estimating a first risk liability value (L1) based on the derived amount of area of the element and the estimated consequence value, wherein estimating a first risk liability value (L1) comprises:

L 1=Σarea ratio for a particular ground hazard*consequence value( C Y ).

2. The method as claimed in claim 1 , wherein deriving the amount of area of the element that falls within a relevant ground hazard category comprises the use of mapping data.

3. The method as claimed in claim 1 , wherein one or more parameters for controlling flight are controlled in relation to the first risk liability values (L1).

4. The method as claimed in claim 2 , further comprising controlling a flight parameter forming part of a collision avoidance procedure.

5. A flight control system for controlling an aircraft system, and comprising a processor and a memory, said memory containing instructions executable by said processor, whereby said flight control system is operative to:

derive a two-dimensional liability map using mapping data related to one or more ground hazard categories, wherein each ground hazard category is associated with a type of hazard on a ground surface; and

wherein the two-dimensional liability map comprises a plurality of risk liability values (L1 or L2) associated with the one or more ground hazard categories; and

use the liability map to control one or more parameters for controlling flight of the aircraft system, whereby said flight control system is operable to derive the two-dimensional liability map by:

dividing a ground surface region of interest into a discretized two-dimensional grid;

for each element of the grid, deriving an amount of area of that element that falls within a relevant ground hazard category;

for each ground hazard category, estimating a consequence value (C Y ) based on a size of the aircraft system; and

for each element of the grid, estimating a first risk liability value (L1) based on the derived amount of area of the element and the estimated consequence value, wherein estimating a first risk liability value (L1) comprises:

L 1=Σarea ratio for a particular ground hazard*consequence value( C Y ).

6. A flight control system operative to perform the method as defined in claim 1 .

7. The flight control system as claimed in claim 5 , wherein the aircraft system is an unmanned aircraft system (UAS).

8. A method for controlling flight of an aircraft system, the method comprising:

deriving a three-dimensional liability map using mapping data related to one or more ground hazard categories, wherein each ground hazard category is associated with a type of hazard on a ground surface, wherein the three-dimensional liability map comprises a plurality of risk liability values associated with the one or more ground hazard categories; and

using the liability map to control one or more parameters for controlling flight of the aircraft system, wherein the step of deriving a three-dimensional liability map is based on a plurality of possible failure modes of the aircraft system and respective probability frequencies of the occurrence of each possible failure mode, and the plurality of failure modes comprises two or more of: uncontrolled glide, controlled glide, and break-up.

9. The method as claimed in claim 8 , wherein deriving the three-dimensional liability map comprises:

dividing a volume of interest into a discretized three-dimensional grid of voxels centered on nodes;

for each node estimating a dispersion pattern for an aircraft system as a result of each failure mode;

for each failure mode estimating a risk liability value for that failure mode; and

summing all the estimated risk liability values for the plurality of failure modes to estimate a second risk liability value (L2) for each node.

10. The method as claimed in claim 9 , wherein estimating a risk liability value for a particular failure mode at a particular node is based on the dispersion pattern for that failure node in relation to the position of the node in relation to the ground surface, and the position of the node in relation to first risk liability values of elements of a two-dimensional liability map.

11. The method as claimed in claim 8 , wherein one or more parameters for controlling flight are controlled in relation to the risk liability values (L1).

12. The method as claimed in claim 8 , wherein one or more parameters for controlling flight are controlled in relation to second risk liability values (L2).

13. The method as claimed in claim 8 , further comprising controlling a flight parameter forming part of a collision avoidance procedure.