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second source
climbed less steeply, to accelerate to FUSS or for power
cutback in noise-abatement procedure, which see.
second source Manufacturer assigned by government to
augment output of major hardware item, eg aircraft or
missile, with assistance of original design company, which
remains in production as first source; no royalty is
normally payable, and ** has no commercial rights to
design, nor permission to sell to third party.
second strike Strategic attack with NW mounted after
enemy’s nuclear attack has taken place; objective of
hardening is to confer a ** capability. DoD: ‘The first
counterblow of a war; generally associated with nuclear
operations’.
second throat That downstream of working section and
upstream of exhaust diffuser in simple blow-down supersonic
tunnel. In operation traversed by weak normal
shock.
second-trace return Caused by large echoing target
outside range scale.
second-user aircraft Also called pre-owned or secondhand.
Secop Single-engine climb-out procedure.
Secor Sequential collation of range. Usually * /DME,
which collates range with distance derived from DME. A
basic technique in global mapping with geodesic satellites.
secretress GA stewardess also serving as office secretary
in flight.
SECS Sequential-events control system.
SECT, Sect Simulator for electronic-combat training.
Sect Sector.
section 1 Cross-section.
2 Major portion of airframe, eg nose*, tail*, but
becomes dangerously ambiguous with wing*, body* when
meaning normally (1).
3 Small subdivision of military air unit, normally
(DoD) two combat aircraft; in 1915–18 four or five; US
in Korea, four.
4 Raw material rolled or extruded to standard (often
complex) cross-section, as distinct from sheet, billets or
strip.
5 Major subdivision of missile or rocket vehicle, eg
guidance*.
6 Subdivision into similar parts, eg six sections of slat.
sectional Noun, VFR navigation chart, equivalent to
ICAO ‘half-million’ (US).
section modulus Moment of inertia of structural member
cross-section divided by perpendicular distance from
neutral axis to outermost surface of section, ie most highy
stressed fibre.
sector 1 Subdivision of air-defence frontier.
2 Limited range of azimuth, eg through which radar
may scan (see * under scan types).
3 Subdivision of airspace by radio range characterized
by letter A or N, also called quadrant.
4 Portion of commercial route between two traffic
points.
sector controller Air-defence controller in charge of
sector (1).
sector display See scan types.
sector distance Length of air route sector (4).
sector fuel That allowed for in flightplan for one sector
(4).
sector management tool Software providing a traffic-
Seenot
management unit with ability to maintain sector integrity
through use of ground delays.
sector scan See scan types.
sector temperature/wind Those met values assumed in
flight-planning one sector (4).
sector time In commercial operation, scheduled or
actual time for sector (4).
sector visibility Within particular sector (2) of horizon
seen from tower.
SECU Spoiler[s] electronic control unit.
secular Having a very long time period, eg a century or
more.
secure Proof against interference by enemy and esp.
against information content of signals being deciphered
by enemy. Various shades of meaning, eg * air refuelling
is one beyond enemy radar range in which all communication
is by lamp.
Secure Flight Computerised passenger pre-screening
system, replacing Capps II (TSA).
Security Over 20 terms relating this topic to aerospace
all appear to be self-explanatory.
SED 1 Safe escape distance; minimum radius from
airbase at which aircraft tail-on is assumed safe against
hostile NW with GZ at airbase.
2 Scanning electron diffraction.
3 Sensor evolutionary development.
4 Systems engineering documentation.
5 Secondary Eicas display.
6 Society of Engineering Designers (UK).
7 Scramjet engine demonstrator.
8 Strategic economic development (US).
SEDF Surface-emitting distributed feedback.
SEDIS, Sedis Surface-emitter detection identification
system (ESM).
Sedris Synthetic-environment data representation [and]
interchange specification.
Seds Students for the Exploitation and Development of
Space (Int.).
SEE 1 Society of Environmental Engineers (UK).
2 Secondary electron emission.
3 Single-event effect.
4 Software engineering environment.
see and avoid Basic onus on pilots in VMC to maintain
lookout.
Seebeck effect Generation of EMF or current by dissimilar
metals in circuit with junctions at different
temperatures (see Peltier).
seeding 1 Aerial dispensing, at controlled rate per unit
time or unit distance, of ECM payload such as chaff, flare
pellets or other dispersed medium including aerosols.
Hence * rate, * distance.
2 Aerial dispensing, at controlled rate per unit time, of
condensation nuclei such as crystals of silver iodide or dry
ice (solid CO 2 ) to trigger precipitation in rainmaking.
seeing 1 Colloq.uially used to mean ability of radar to
reach highly reflective part[s] of target.
2 Quality of observability (astronomy).
seeker Device able to sense radiation from target, lockon
and steer towards it, using radar (active or
semi-active), optics (usually passive), laser or IR; rarely
other methods. Normal sensor for terminal guidance of
missiles and other guided ordnance.
Seem Side-emitting electronic manifold [radar].
Seenot Air/sea rescue, prefix to longer words (G).
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