ISO 1151-7:2023

INTERNATIONAL ISO
STANDARD 1151-7
Second edition
2023-11
Flight dynamics — Vocabulary —
Part 7:
Flight points and flight envelopes
Dynamique de vol – Vocabulaire —
Partie 7: Points de vol et domaines de vol
Reference number
© ISO 2023
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Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Accomplishment of a mission . 1
3.2 Controls, geometric configuration and condition of systems . 2
3.3 State of the aircraft . 3
3.4 Environment . 4
3.5 Flight points . 5
3.6 Effective flight points . 6
3.7 Flight envelopes . 7
Bibliography . 8
Index . 9
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Foreword
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This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 8, Aerospace terminology.
This second edition cancels and replaces the first edition (ISO 1151-7:1985), which has been technically
revised.
The main changes are as follows:
— new terms for subclause “Types of aircraft motion” have been supplemented.
A list of all parts in the ISO 1151 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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INTERNATIONAL STANDARD ISO 1151-7:2023(E)
Flight dynamics — Vocabulary —
Part 7:
Flight points and flight envelopes
1 Scope
This document defines the concepts and terms used in flight dynamics studies to specify aircraft flight
conditions and envelopes.
This document applies to the analysis of operational, experimental or simulated flights for the purposes
of safety analyses and qualification, taking into account potential failures and likely environmental
conditions.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Accomplishment of a mission
3.1.1
mission
purpose of a flight achieved while respecting constraints, among others, of time and of space
Note 1 to entry: The objective and the constraints can be specified in a flight plan.
3.1.2
flight program
preschedule of intermediate objectives required to fulfil the mission (3.1.1) within an authorized flight
envelope (3.7.1)
Note 1 to entry: Provision can be made in the flight programme for some conditional changes of intermediate
objectives according to circumstances arising during the flight (failure, meteorology, traffic, etc.).
3.1.3
phase
flight phase
portion of the flight characterized by an intermediate objective
Note 1 to entry: The intermediate objective is defined with some tolerance as to the accuracy with which the
objective is considered to have been achieved, such that the following phase can be initiated under conditions
that allow it to be executed.
Note 2 to entry: Examples of flight phases are: take-off, climb, cruise, descent, approach, landing.
3.1.4
sub-phase
flight sub-phase
portion of a phase (3.1.3) characterized by an elementary objective
EXAMPLE "Ground run" in the "take-off" phase, "flare" and "ground run" in the "landing" phase.
Note 1 to entry: The elementary objective is defined with some tolerance as to the accuracy with which the
objective is considered to have been achieved, such that the following sub-phase can be initiated under conditions
that allow it to be executed.
Note 2 to entry: Following the breakdown of a phase into sub-phases, certain parameters can often be considered
as constants during the sub-phase [e.g. mass characteristics of the aircraft, state of the atmosphere (3.4.1)].
3.2 Controls, geometric configuration and condition of systems
3.2.1
control
element located in the cockpit and operated by the crew to fly the aircraft
EXAMPLE Stick; throttles; undercarriage and flap selection levers; switches to engage autopilot or dampers;
pressurization and air conditioning controls.
Note 1 to entry: The same control can be a piloting control (3.2.1.1) during one sub-phase (3.1.4) and a selector
(3.2.1.2) during another sub-phase; for example, the throttle is a selector during the "take-off" phase and a
piloting control during the "approach" phase.
3.2.1.1
piloting control
control (3.2.1) operated by the pilot, in a continuous or intermittent manner, during a sub-phase (3.1.4)
in order to comply with the piloting rules (3.5.1) and to achieve the objective of that sub-phase
3.2.1.2
selector
control (3.2.1) put into a position by the crew, as laid down in the flight manual, at the beginning of a
sub-phase (3.1.4) and which remains in that position throughout that sub-phase
3.2.2
configuration
geometric configuration
set of quantities characterizing the relative positions of the various components of the aircraft, that can
be controlled by selectors (3.2.1.2)
Note 1 to entry: See ISO 1151-6:1982, 6.0.2.
Note 2 to entry: The list of quantities is restricted to those involved in the problem under consideration.
Note 3 to entry: The geometric configuration shall not be confused with the geometric state (see ISO 1151-1-6:1982,
6.1.17) of which it forms only a part.
3.2.3
situation of the systems
set of parameters defining the operating behaviour of the aircraft systems concerned with flight
dynamics
Note 1 to entry: The list of parameters is restricted to those involved in the problem under consideration.
3.3 State of the aircraft
3.3.1
situation of loads carriage
list of the different internal or external loads (passengers, freight, containers and pallets, fixed or
jettisonable fuel tanks, internally or externally carried stores, etc.) for a given mission (3.1.1), with their
positions, that modify the mass, the mass distribution, and, in certain cases, the geometric form of the
aircraft
Note 1 to entry: Internal fuel is not included in these loads. For flight refuelling tankers, fuel is considered to be
a load.
Note 2 to entry: For certain missions, the situation of loads carriage can be modified during a transition sub-
phase (3.1.4) (e.g. by jettisoning stores or dropping parachutists). See note 1 to entry in 3.3.2.2.
3.3.2
selected situation
list of the set of positions of the different selectors (3.2.1.2) during a sub-phase (3.1.4)
Note 1 to entry: For each sub-phase, there is a single selected situation, defined either in the flight manual for
operational flights or in the study programme for experimental flights.
Note 2 to entry: The selected situation can be divided into two sub-sets: a selected geometric configuration
(3.3.2.1) and a selected situation of the systems (3.3.2.2).
Note 3 to entry: An order to change the position of a selector may not be associated with a geometric displacement
of the selector itself, but may be achieved by appropriate signalling.
3.3.2.1
selected geometric configuration
list of the set of positions of only those selectors (3.2.1.2) concerned with the geometric configuration
(3.2.2) of the aircraft during a sub-phase (3.1.4)
3.3.2.2
selected situation of the systems
list of the set of positions of only those selectors (3.2.1.2) concerning the systems (3.2.3) during a sub-
phase (3.1.4)
Note 1 to entry: Certain sub-phases, called transition sub-phases, are characterized by the change either in the
position of components or in the state of the systems controlled by the change in the position of one or of several
selectors. The duration of the transition sub-phase is then determined by the time taken to change the position of
the components or the state of the system, for example, sub-phase "undercarriage out".
Note 2 to entry: In certain studies, and in particular during a flight test, it can be useful to study the behaviour of
the aircraft in positions of the components or for system functions that do not usually occur during operational
flights. For example, the flight can be studied at low incidence with leading edge slats extended or at high incidence
with slats retracted, even though in operational flight the position of the slats can be automatically fixed by the
incidence and the speed. To describe those particular selected situations (3.3.2), it is necessary to indicate that
the automatic system has been made inoperative by a selector activated specifically for that purpose.
3.3.3
failure situation
list of the set of abnormal positions of components and of the set of abnormal functions of the systems
during a sub-phase (3.1.4)
Note 1 to entry: See ISO 1151-6:1982, 6.0.2.
Note 2 to entry: The failure of a system, the operation of which is not involved in a sub-phase, shall be taken into
consideration in defining the failure situation, because it can modify the probability of failures in that sub-phase
or in other sub-phases.
Note 3 to entry: In line with this definition, the non-operation of one of the lines of a redundant system shall be
considered as a failure, even if the other lines maintain the function of the system. In those conditions, the failure
situation is said
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