FlightCom – August 2019

9 FlightCom Magazine

S

ANSA is the key custodian of

two essential aspects of aviation –

the ‘standard reference’ compass

against which all aircraft compasses are

calibrated, and the provision of warnings of

solar storms.

It is an old truism to say that the source

of all weather phenomena on Earth is the

Sun. The term ‘Space Weather’ describes

those events caused by the sun that happen

in space, which can in particular, disrupt

GPS signal quality as well as power grids,

navigation and communication systems.

SANSA, based at Hermanus in the

Western Cape, has been selected by the

International Civil Aviation Organization

(ICAO) as one of two regional centres to

provide Space Weather services, including

solar storm forecasts and warnings,

to the global aviation sector. “With

aviation, we consider four key risk areas –

communication, navigation, avionics and

radiation exposure,” said SANSA MD, Dr

Lee-Anne McKinnell. “High frequency

radio communication, as well as ground

and air-based navigation systems, can be

affected or knocked out entirely by space

weather storms. Delicate electronics can

also be damaged, and radiation exposure

poses a hazard for crew and passengers,

particularly on long haul flights.” Space

weather can also have a major knock-on

effect on airlines and airports.

The other key competency of SANSA

with direct relevance to general aviation

is compass accuracy. Despite the rise of

modern navigation systems such as GPS

and radio aids, compasses are still an

essential component of aircraft navigation

equipment. Electrical systems may fail,

but the Earth’s magnetic field never does.

However, it is continuously changing

and that requires constant monitoring to

determine the degree of compass variation

at any specific place.

The need for accurate compass

swinging by properly qualified technicians

was highlighted by the recent incident of

the South African Civil Aviation Authority

grounding part of a local Airline’s fleet

because it claimed the compass swings

had not been properly done. This stranded

thousands of high-value tourists over the

holiday season. SANSA points out that

a proper compass swing procedure is

necessary to determine how to measure and

compensate for the magnetic field of the

actual aircraft, which will cause a deviation

to the compass reading once located in

the cockpit, due to the proximity of steel

or iron components, and by the effects of

current flowing in nearby electrical circuits.

The compass must therefore be swung at

predetermined intervals, usually at the

annual Mandatory Periodic Inspection or

at any time when the magnetic properties

of an aircraft have changed, by for instance

the installation of new equipment or a direct

lightning strike.

A properly conducted compass swing

requires a calibrated reference compass,

and it must be done in a magnetically

clean environment free of steel structures,

underground cables, or equipment that

produces magnetic fields, to assure it is

free of interference. And as the grounding

of the airline’s fleet demonstrated, it must

be done by qualified personnel. SANSA’s

Space Science facility in Hermanus is the

only SACAA accredited South African

facility that offers this type of service with

the necessary expertise and facilities to

perform on-site training in the compass

swing procedure.

SANSA has been presenting training

courses on the execution of compass

swings to the South African Air Force for

more than 20 years and recently hosted a

five day Compass Swing Training Course

and a three day Compass Swing Refresher

Course. The course is presented by SANSA

engineers and physicists who have many

years of relevant magnetic navigation

ground support experience.

For more information on these services

and courses email: spacesci-info@sansa.

org.za

The name of The South African National Space Agency (SANSA) may suggest that it

is concerned with matters far higher than atmosphere-bound aviation. But SANSA

performs a key service to all aircraft and their operators.

SA SPACE AGENCY’S KEY

ROLE IN AVIATION

Company Profile

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Having a calibrated

Compass is essential for

any aircraft's compass

swings - which must

be done annually.

Guy Leitch