Page 22 - 2018-Issue1

SPACE WEATHER 22

Captain James Gaskell retired from Thomson Airways (TUI
Airways) in 2010 after 33 years, (30 years as a Captain) on B737,
then B757 and B767. Previously, he served 8 years in the Royal Air
Force. Gaskell has been a member of the British Airline Pilots’ Air
Traffic Services Study Group (BALPA ATS SG) for several decades
and has attended many IFALPA ATS Committee meetings, most
recently in Singapore. He wrote this article in consultation with
Captain Klaus Sievers and Mark Gibbs, who is in charge of Space
Weather at the UK Met Office.

Kp Graph provided by NOAA SWPC

RADIATION STORMS The nearest satellite to the Sun is the Deep Space Climate
One hundred billion neutrinos from nuclear reactions in the Observatory (DSCOVR), a million miles sunwards orbiting the
core of the Sun pass through each square centimetre of our Lagrange 1 point. Although a CME might be observed heading
bodies every second. They do us no harm whatsoever because in our direction, only when it passes DSCOVR, 20 to 60 minutes
they are not stopped by our bodies. Radiation produces ill effects before arrival at Earth’s orbit can there be certainty about its
on us when it knocks electrons out of atoms or changes atomic details, particularly the magnetic polarity. The remaining Stereo
nuclei. Radiation warnings from SWPC and MOSWOC are A satellites, (currently approximately 120 degrees behind the
triggered by solar proton fluxes measured by GOES exceeding Earths orbital position) help forecasters determine the speed of
certain levels and energies (>10 MeV and >100 MeV). A report CMEs, with the faster ones being of greater concern.
published by the Royal Academy of Engineering assessed the Coronal Mass Ejections consist of plasma, the fourth state of
modern-day impacts of a repeat Carrington Event (the largest matter, mainly ionised hydrogen which has strong magnetic
space weather event in recorded history) that occurred in 1859. fields. If they impact the vicinity of the Earth they alter the Earth’s
The report suggests that a similar event today would likely induce magnetic field. The degree of change is measured by the Kp index
flight cancellation for aircraft on the ground, diversion for which can be seen on the Geomagnetic Activity chart. Kp
long-haul aircraft airborne and altitude reduction, where safe, for reached 8 (G4 severe storm) late on 7th September. This was
the rest. Reducing altitude significantly reduces received caused by a CME associated with the earlier flare.
radiation because of atmospheric absorption. Any change of magnetic field, by Maxwell’s Laws, induces a
Radiation exposure is governed by international agreement. voltage which can affect power supplies. Large areas around
“As Low As Reasonably Achievable (ALARA) taking into account Montreal were put into darkness in 1989. Geomagnetic Storms
social and economic factors,” is the principle applied. To disturb the Ionosphere as do the Xrays from Solar Flares. GPS
constantly fly 4,000 feet above optimum increases radiation position becomes less accurate when the Ionosphere is disturbed.
exposure undesirably, particularly at high latitudes as well as The use of augmentation systems both local and wide area helps.
reducing manoeuvre margin. To fly 10,000 feet below is A signal is sent to augmentation satellites which transmit a
economically unreasonable. Radiation warnings need greater modification over a wide area. As an aside, relativistic corrections
accuracy and specificity to be heeded routinely by pilots. to the GPS clocks have to be made to allow for their speed and
GEOMAGNETIC STORMS height in Earth’s gravitational field.
Severe geomagnetic storms are caused by Coronal Mass When the magnetic fields on the Sun “break”, releasing a
Ejections (CMEs) which consist of billions of tons of plasma CME and then reconnect, producing a solar flare, a “radio burst”
accelerated away from the Sun by magnetic energy freed by the is also produced from the same location. One such radio burst
breaking and reconnection of magnetic fields on the Sun. caused the secondary radar in Sweden to be disabled for a time
Forecasting the eruption of a CME is not yet possible and the on 4th November 2015 Near sunset, the Sun was in direct “line of
orientation of the magnetic field within the CME is a major sight” of the secondary surveillance radar.
challenge in space weather and at the cutting edge of research. The NOAA SWPC website will provide you with an email
CMEs typically take between 2 and 5 days to travel the 93 million alerting service. Just sign up for it. Often little advanced notice of
miles from the Sun to the Earth, with the fastest on record significant Space Weather is given. This is the nature of an, as yet,
making the journey in approximately 15 hours. immature system.

ISSUE 1 | 2018 InterPilot | The Safety and Technical Journal of IFALPA