Yo

#define MAX_MISSILES 4
#define MAX_PLANES 2

typedef struct Missile
{
    unsigned char dir;
    unsigned short distance; // distance between the plane and the missile
    unsigned char type;
} Missile;

// plane management
typedef struct Plane
{
    int x;
    int y;

        /* plane direction management
        3      2     1
        4    plane   0
        5      6     7
        */

    unsigned char dir;
    unsigned char life;

    Missile missiles[MAX_MISSILES];
    // align
} Plane;

Plane planes[MAX_PLANES];

/*
accés :
int i = 0; j = 0;
planes[i].missiles[j].dir ?
*/