A method for accessing a navigation database by means of an on-board computer, said navigation database being intended to be integrated into a navigation system for an aircraft comprising said computer, said database comprising: a first set of elements, called Fix, particularly comprising representations of airports, beacons and waypoints, as well as the geographical coordinates of said Fix; a second set of elements comprising procedures, each procedure being defined by a succession of transitions, said transitions comprising a set of manoeuvres of said aircraft, the manoeuvres being instructions predefined in said navigation system; a third set of elements comprising representations of routes formed by a succession of waypoints and/or airports, characterised in that said method comprises a step of creating an index pair comprising: a first alphanumeric index (INDEX 1) comprising: the elements of said first, second and third sets; attributes of each element, said attributes comprising at least the identifier, the type and the functional identifier of said element; a first list of pointers, each pointer being associated with an element, designating the memory address where the elements are stored in said navigation database, said first index being ordered according to at least one type of attributes, called AT_ORD, an alphanumeric pre-index (INDEX 2) comprising: a list of codes (PR_CAR), each code being unique and corresponding to a predetermined number of the first characters of each item of data of the AT_ORD of each element of said navigation database; a second list of pointers, each pointer being associated with a code and pointing at the identifier, in said first index, of each first element, the AT_ORD of which comprises the associated code. a first set of elements, called Fix, particularly comprising representations of airports, beacons and waypoints, as well as the geographical coordinates of said Fix; a second set of elements comprising procedures, each procedure being defined by a succession of transitions, said transitions comprising a set of manoeuvres of said aircraft, the manoeuvres being instructions predefined in said navigation system; a third set of elements comprising representations of routes formed by a succession of waypoints and/or airports, a first alphanumeric index (INDEX 1) comprising: the elements of said first, second and third sets; attributes of each element, said attributes comprising at least the identifier, the type and the functional identifier of said element; a first list of pointers, each pointer being associated with an element, designating the memory address where the elements are stored in said navigation database, said first index being ordered according to at least one type of attributes, called AT_ORD, the elements of said first, second and third sets; attributes of each element, said attributes comprising at least the identifier, the type and the functional identifier of said element; a first list of pointers, each pointer being associated with an element, designating the memory address where the elements are stored in said navigation database, an alphanumeric pre-index (INDEX 2) comprising: a list of codes (PR_CAR), each code being unique and corresponding to a predetermined number of the first characters of each item of data of the AT_ORD of each element of said navigation database; a second list of pointers, each pointer being associated with a code and pointing at the identifier, in said first index, of each first element, the AT_ORD of which comprises the associated code. a list of codes (PR_CAR), each code being unique and corresponding to a predetermined number of the first characters of each item of data of the AT_ORD of each element of said navigation database; a second list of pointers, each pointer being associated with a code and pointing at the identifier, in said first index, of each first element, the AT_ORD of which comprises the associated code.