The 1995–96 eruptions at Ruapehu had a significant impact on New Zealand’s aviation industry, resulting in the cancellation and diversion of many flights (Lechner, 2012). The reported economic cost to the aviation industry at the time as a result of these eruptions was approximately NZ$2.4 million (Johnston et al., 2000). Based on experiences from this eruption episode, the Civil Aviation Authority (CAA) of New Zealand reviewed its procedures and those used internationally to refine the Volcanic Ash Advisory System (VAAS; Lechner, 2012). Internationally, many other instances of impacts on the aviation industry have occurred, including the costly near shut-down of airspace in Europe following an eruption at
Eyjafjallajökull in Iceland in 2010, and the impact on aviation in the Southern Hemisphere in 2011 from the Puyehue-Cordón Caulle eruption in Chile, which caused an ash cloud to circulate the globe.
Organisations and tools used to communicate volcanic ash information to the civil aviation industry are rife with acronyms. The CAA assists the civil aviation industry in managing the use of air space in proximity to volcanic ash (Lechner, 2012). The New Zealand VAAS is the local implementation of the International Civil Aviation Organization (ICAO) International Airways Volcano Watch system (IAVW). GNS Science, the Meteorological Service of New Zealand (MetService), Airways Corporation of New Zealand, and aircraft operators provide input into the VAAS (Scott & Travers, 2009; Lechner, 2012). New Zealand’s Volcanic Ash Advisory Centre
2
http://www.gns.cri.nz/Home/Learning/Science-Topics/Volcanoes/Eruption-What-to-do/Ash-Impact- Posters, accessed on 10 January 2014
(VAAC), based at the MetService office in Wellington, is designated by the IAVW to communicate ash information for a large section of the southwest Pacific, including
New Zealand’s active volcanoes (Lechner, 2012). MetService issues Volcanic Ash Advisories in text and graphic form, and disseminates NOTAMs (Notice to Airmen), which describe hazards along a flight route. These are issued when the VAL changes, prompting Volcanic Hazard Zones (referred to as NZVs) to be created. Restrictions on the use of airspace during a volcanic eruption using the VAAS and the NZVs are outlined in Lechner (2012). After consultation with GNS Science, Volcanic Ash Advisories are also communicated to MCDEM, in addition to being provided to international aviation agencies, and meteorological communities (MCDEM, 2006). Volcanic Ash Advisories from MetService forecast the distribution of tephra in the atmosphere for the purpose of aviation safety, whereas GNS Science issues ashfall prediction maps relating to the distribution and thickness of tephra deposits at ground level.
GNS Science issues Volcano Observatory Notices for Aviation (VONA) to the VAAC at MetService to report on ground-based volcanic activity whenever there is a change in the Aviation Colour Code (ACC; Table 2.2). VONAs are “succinct, plain-English messages” aimed at pilots, dispatchers, and air-traffic controllers (as described on the USGS website3). The ACC is defined by the ICAO and allocated by GNS Science, and is used by the CAA in New Zealand to alert the aviation industry to changes in the status of volcanoes within the designated
coverage area (Lechner, 2012). While VAACs provide the aviation community with information regarding where ash currently is in the air, the role of the ACC is more about warning (Gardner & Guffanti, 2006). This encompasses the recognition of the level of volcano activity for the purpose of attention by the aviation industry, and to inform their decisions, such as regarding re-routing or extra fuel (Gardner & Guffanti, 2006). The ACC relates to activity at or near a volcano and is not intended to apply to volcanic hazards occurring at a distance, such as ash drifting downwind (Lechner, 2012). The international nature of the ACC reflects the need for aviation personnel to ascertain the status of volcanic activity across a number of countries and VAL systems (e.g., Guffanti & Miller, 2013; and as described by the World Organization of Volcano Observatories website4). Meanings placed on the levels in the ACC by the USGS are described further in Gardner and Guffanti (2006).
3
http://volcanoes.usgs.gov/activity/vonainfo.php, accessed 20 October 2013
4
Chapter 2 New Zealand’s Volcano Early Warning System
54
Table 2.2. The International Civil Aviation Organization (ICAO) Aviation Colour Code (ACC) for volcanic activity. Source: Lechner (2012).
ICAO Colour Code Status of activity of volcano
GREEN
Volcano is in normal, non-eruptive state. Or, after a change from a higher alert level:
Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.
YELLOW
Volcano is experiencing signs of elevated unrest above known background levels.
Or, after a change from a higher alert level:
Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE
Volcano is exhibiting heightened unrest with increased likelihood of eruption.
Or, volcanic eruption is underway with no or minor ash emission [specify ash-plume height if possible].
RED
Eruption is forecasted to be imminent with significant emission of ash into the atmosphere likely.
Or, eruption is underway with significant emission of ash into the atmosphere [specify ash-plume height if possible].
2.4.2.2 Communication of other volcano-related information: Volcanic Alert Levels