Space weather effects on airline communications in the high latitude regions

Lead Research Organisation: University of Leicester
Department Name: Engineering

Abstract

Efficient air traffic management depends on reliable communications between aircraft and the air traffic control centres. However there is a lack of ground infrastructure in the Arctic to support communications via the standard VHF links (and over the Arctic Ocean such links are impossible) and communication via geostationary satellites is not possible above about 82 degrees latitude because of the curvature of the Earth. Thus for the high latitude flights it is necessary to use high frequency (HF) radio for communication. HF radio relies on reflections from the ionosphere to achieve long distance communication round the curve of the Earth. Unfortunately the high latitude ionosphere is affected by space weather disturbances that can disrupt communications. These disturbances originate with events on the Sun such as solar flares and coronal mass ejections that send out particles that are guided by the Earth's magnetic field into the regions around the poles. During such events HF radio communication can be severely disrupted and aircraft are forced to use longer low latitude routes with consequent increased flight time, fuel consumption and cost. Often, the necessity to land and refuel for these longer routes further increases the fuel consumption. The work described in this proposal cannot prevent the space weather disturbances and their effects on radio communication, but by developing a detailed understanding of the phenomena and using this to provide space weather information services the disruption to flight operations can be minimised.

The occurrence of ionospheric disturbances and disruption of radio communication follows the 11-year cycle in solar activity. During the last peak in solar activity a number of events caused disruption of trans-Atlantic air routes. Disruptions to radio communications in recent years have been less frequent as we were at the low phase of the solar cycle. However, in the next few years there will be an upswing in solar activity that will produce a consequent increase in radio communications problems. The increased use of trans-polar routes and the requirement to handle greater traffic density on trans-Atlantic routes both mean that maintaining reliable high latitude communications will be even more important in the future.

Planned Impact

Main beneficiary - the airline industry

The main beneficiary of the proposed research is airline industry. Commercial polar operations began in 1999 with a small number of proving flights. The rapid increase in the number of commercial airline flights over the northern polar region (328 in 2000, rising to 10025 in 2010) provides a high demand for reliable HF radio communications. Based upon experience during previous periods of high solar activity, United Airlines estimated that their additional operational costs will be as high as $13M per year. Similar increased costs will be incurred by other major airlines operating over polar routes. The avoidance of these high additional costs relies on reliable HF communication predictions. In 2000, NAVCANADA [Rome, 2000; Fisher and Jones, 2007] conducted a feasibility study that identified 33 potential city pairs that could benefit from routing aircraft over the poles. On such routes, flight-time savings of two to three hours and financial savings of £20,000 per flight are typical. During an aviation workshop [Fisher and Jones, 2007], commercial and operational details were given for solar activity impacts upon three specific polar operations for the period 17-24 January 2005 that amounted to $250k in visible costs (fuel and time). Estimates for hidden costs (missed passenger connections, cargo, etc) could be as much as $100k per flight. From a European perspective, flights to the west coast of North America and to Hawaii are affected.

Operational planning for flights on polar routes commences 8-12 hours prior to dispatch, and requires the expected quality and availability of HF radio communications to be known for the duration of the flight. Improved predictions, forecasts and nowcasts of HF propagation conditions are needed to avoid unnecessary delays, re-routes and diversions, and reduce fuel usage, maintenance and operational costs. Such improvements will also lead to greater safety.

Other Beneficiaries:

The Evironment: The aviation industry is currently considered to have a significant impact on the environment and global warming. When geomagnetic storms divert flights from the polar routes to non-polar routes, time penalties of 2-3 hours can be incurred with an associated increase of fuel used by as much as 50 tonnes per hour (equivalent to 140 tonnes per hour of extra CO2). In addition, the re-routing may require en-route stops adding 3-4 hours in journey time and significant further increases in fuel usage. Thus in addition to improvements in the HF communications, there will be a significant reduction in environmental pollution resulting from the proposed research.

Maritime: In addition to the airline industry, the results of the project will be of direct benefit to the maritime industry for communications with shipping in the Arctic regions. The likely increase in ship traffic in polar regions, as a result of receding ice fields, will create new requirement for maritime HF communications since geostationary satellites do not cover these areas. The efficiency of maritime transport in polar regions, the assessment of risk levels and provision of risk mitigation measures will depend on the ability to forecast the effects of space weather events on terrestrial position-fixing and communications systems. Passage planning for minimum fuel usage and prediction of voyage duration to ensure timely arrival and availability of port facilities will make demands on forecasting services, which will need to be based on understanding of space weather effects on communication and navigation systems.

General Public: Outreach to the wider public is an essential part of this research project, particularly communicating to school children the importance of science whilst keeping them enthused.

Publications

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A.J. Stocker (2013) Space Weather Effects on Airline HF Radio Communications in the High Latitude Regions in European Space Weather Week, Antwerp, 18-22 November 2013

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F. Honary (2014) Space Weather effects on airline communications in the high latitude regions in European Geosciences Union General Assembly, Vienna, 22 April-2 May 2014

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F. Honary (2013) Space Weather effects on airline communications in the high latitude regions in Space weather: a dialogue between scientists and forecasters, Royal Astronomical Society, 13 December 2013

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N.C. Rogers (2013) Improving HF Communications Availability Forecasts for Aircraft on Trans-Polar Routes in European Space Weather Week, Antwerp, 18-22 November 2013

 
Description A ray-tracing method has successfully been used to model the effects of the polar ionosphere on HF signals for historical scenarios. In order to enable this model to be applied in nowcasting and forecasting for operational systems (e.g. the prediction of communications with commercial aircraft prior to dispatch (forecasting) and for frequency management during flight (nowcasting)) over a period of a few hours, we have incorporated data from a number of sources including ionosondes and GPS to provide real-time estimates of the background ionosphere and the number and intensity of patches.

We have successfully moved to an IRI based ionospheric model using TEC measurements to provide what will become a real time input driving the IG and RZ parameters to provide agreement between TEC and HF communications parameters such as foF2. Good agreement has been obtained between the the old and new methods for 8.0 MHz, but there are differences that are particularly noticeable at 11.1 MHz. Further developments are required in order to improve performance and further testing is required to compare modelled values with measured values, in particular noting that small changes in the background electron density can lead to significant changes in the coverage particularly at distances close to the skip distance. It should also be noted that using the IRI with the monthly IG and RZ values gives us a fall-back position should the required real-time data become unavailable at times.

While ionosonde and TEC measurements will help establish the presence and intensity of patches, it is more difficult to determine the exact number of patches and their physical extent (since time and space are convolved in the GPS measurements because both the point where the path from the satellite to the ground intersects the ionosphere, the pierce point, and the patch are moving). However, there will be occasions when the same patch will affect the TEC on several GPS satellites (i.e. where the patch is larger than the separation of the pierce points), which will allow the size of that patch to be estimated. In view of the uncertainty in patch numbers, positions and intensities, the simulation may be run with a range of different values of the patch parameters in order to establish an ensemble average for the coverage maps.
Exploitation Route We are currently working with the Met Office and SolarMetrics to take this work forward with the aim of providing a service to airlines.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software)

 
Description We are currently working with Lancaster University, the MetOffice and SolarMetrics to develop a commercial service providing nowcasting and forecasting of HF communications for aircraft on polar routes. This is in the early stages.
First Year Of Impact 2016
Sector Aerospace, Defence and Marine
Impact Types Economic

 
Description ARTES 20 Integrated Applications Promotion Programme
Amount € 153,413 (EUR)
Funding ID 4000121287/17/NL/US 
Organisation ESA - ESTEC 
Sector Public
Country Netherlands
Start 09/2017 
End 05/2018
 
Description HARP: High Latitude Aeronautical Radio Prediction Service 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Public 
PI Contribution We bring HF propagation expertise developed with EPSRC support to a project to develop an HF communications forecasting service for airlines operating over polar routes.
Collaborator Contribution Met Office: Expertise in delivering forecasts on a commercial basis to a range of users. SolarMetrics: Expertise in the airline industry, including space weather effects.
Impact No outputs at present. CVurrently undertaking a feasibility study.
Start Year 2017
 
Description HARP: High Latitude Aeronautical Radio Prediction Service 
Organisation SolarMetrics Ltd
PI Contribution We bring HF propagation expertise developed with EPSRC support to a project to develop an HF communications forecasting service for airlines operating over polar routes.
Collaborator Contribution Met Office: Expertise in delivering forecasts on a commercial basis to a range of users. SolarMetrics: Expertise in the airline industry, including space weather effects.
Impact No outputs at present. CVurrently undertaking a feasibility study.
Start Year 2017