New Strategies and Engineering Technologies for Dealing with Volcanic Ash

Abstract

This report discusses the state of current strategies and technologies designed to avoid damage to aircraft from volcanic ash, and the limitations current technologies present with respect to the recent Eyjafjallajokull Icelandic volcanic eruption. Future strategies and technologies are critically examined to determine the limitations, requirements and cost of implementation.
Ash cloud avoidance strategies appear to be the most viable option. A technology entitled AVOID (Airborne Volcanic Object Imaging Detector) is currently being tested on the United Kingdom’s biggest airline EasyJet which uses an infrared camera to detect ash particles and gases present in volcanic ash. Whilst this technology exists, it is unknown whether other airlines will adopt the technology, and whether the government will support it; in spite of of the huge economical cost the Eyjafjallajokull volcano caused for European airlines and in shipping delays. What is known is that this was not an isolated incident and volcanoes will continue to erupt as long as the earth exists.

Table of contents

Introduction 4

Current strategies and technologies for dealing with volcanic ash 4 - 5

Future strategies and technologies for dealing with volcanic ash 5 - 6

Conclusion 7

References 8

Introduction

On the 14th April 2010 a volcano named Eyjafjallajokull, Icelandic for “Island mountain glacier” erupted sending an estimated 250 million [pic] of ash and gas into the atmosphere. The ash cloud drifted over Europe leaving European aviation authorities no choice but to close airspace for 6 days, cancel 100,000 flights and leave 7 million passengers stranded. And this was not even a major eruption, according to Mathew Jones a glacier expert who monitors Iceland’s volcanic activity (Sherwell, p 2010). Volcanic ash is extremely volatile containing bits of pulverized rock and glass that are abrasive, corrosive and statically charged, if ingested into the engine the particles can melt and then solidify on turbine blades disrupting cooling, distorting blades and causing engines to subsequently surge and seize (Hayward, K 2011). This is but a sample among a myriad of detrimental effects volcanic ash can have on an aircraft. The following paragraphs discuss existing technologies and their limitations and reveals new technologies and strategies that will enable aircraft to continue flying in the presence of volcanic ash.

Current strategies and technologies for dealing with volcanic ash

Aircraft are not physically designed to deal with the dangers of flying through volcanic ash, nor are they able to detect ash with their current radar systems, instead relying on procedures issued by the airline manufacturer and aviation regulators, and other facilities that have the ability to detect ash and subsequently warn aircraft of its location. Volcanic Ash Advisory Centers (VAACs) were setup by the International Civil Aviation Organization (ICAO) in 1995. They were created to monitor volcanic activity, track and forecast the direction of volcanic ash clouds (Hayward, K 2011). There are currently 9 VAACs located across the globe each with its own jurisdiction shown in image 1 on page 5. VAACs use a variety of methods for the detection of volcanic ash with some of the available methods specific to certain jurisdictions.

The most common and effective technique is the Advance Very High Resolution Radiometer (AVHRR). Located onboard a satellite, the AVHRR detects the differences in absorption and radiation between water, ice and ash clouds in specific infrared bands (Barnes, C 2011). AVHRR has been subsequently updated since its inception, to include other sensitive infrared bands that detect other elements common to volcanic ash such as sulfur dioxide (SO2), to enable tracking of the cloud even when it has become largely dispersed. AVHRR is commonly used in conjunction with an atmospheric dispersion model for example NAME (Numerical Atmospheric-dispersion Modeling Environment) used by the London VAAC or PUFF used by the Washington VAAC (Ellrod, G 2010).

The combination of AVHRR and a dispersion model have been useful for protecting aircraft, however there is still a degree of error present in the predictions and this method leads to wide scale airspace closures. Guy Graton head of Airborne Atmospheric Measurements at Cranfield University stated at the recent RAeS conference “economically we need to fly but safety must be maintained; we need better forecasting to reduce levels of uncertainty” (Hayward, K 2011).

[pic]

Image 1: VAACs location and jurisdiction across the globe, red areas are not monitored (Ellrod, G 2010).

Future strategies and technologies for dealing with volcanic ash

Since the recent volcanic eruption in Iceland that disabled major areas of European airspace, Aerospace companies have been looking for new technologies to avoid and reduce the affect of volcanic ash on aircraft operations. Improving current volcanic ash detection methods will provide more accurate results and reduce airspace closures satisfying short term goals, however it will be necessary in the future to either actively detect volcanic ash and avoid, or design and enable aircraft to fly in areas of low volcanic ash density with minimum effects on the lifetime of aircraft components.

6 days after the eruption of the Eyjafjallajokull volcano on the 20th of April 2010 the major civil aircraft engine manufactures including Rolls Royce, Pratt and Whitney and General Electric met with FAA representatives to discuss the effects of aircraft flying in low density ash clouds. An agreement was made to allow aircraft to fly in “ash concentration levels of less than 2 milligrams per cubic meter and in the absence of visible volcanic ash” and any flight operating within those bounds to be monitored for long term impact on the engine (Dinius, R 2010). Following the consensus between the FAA and the engine manufacturers any aircraft that was known to have flown through an ash cloud was monitored to provide samples to build a log of the effects. The decision enabled more aircraft to fly, however ground controlled testing where considered necessary to determine the effects of higher concentrations and produce more qualitative data.

Commercial aircraft engines currently require ingestion tests, were ice and birds are fired into the inlet of an operating turbofan In compliance with airworthiness regulations. Rolls Royce and General Electric are looking at performing similar tests with volcanic ash in order to produce ash tolerant engines however complications exist with this kind of testing and optimization. Although the basic composition of ash is known and could be recreated, there are no standards yet for the amounts of each component present in a certain density of ash, with gases, pulverized rock and glass all dissipating at varying rates and ash constituents varying from volcano to volcano, determining a standard for volcanic ash for testing will require substantial time and research ((IVATF), 2010). Optimizing an engine to handle ash will also reduce performance as preventing ash from melting and sticking to engine components will require a reduction in operating temperature reducing the engines efficiency, increasing fuel burn and emissions (Hayward, K 2011).

Due to the cost of research, redesign and the reduction in performance an ash tolerant engine presents, a more suitable option for aircraft is to avoid ash clouds altogether whilst keeping them airborne. The Norwegian Institute for Air Research (NILU) lead by doctor Fred Prata has developed a system called the Airborne Volcanic Object Imaging Detector (AVOID), that uses an infrared radiation camera modified for airline use entitled “Ashcam” to detect ash and sulfur dioxide (SO2) particles at concentrations of less than 0.2 milligrams per cubic meter, not unlike the satellite mounted AVHRR. The AVOID system is used in conjunction with satellite data and algorithms to produce interpretable images of ash clouds and water concentrations up to 100 kilometers away with a vertical view range of 15 kilometers ((NILU), 2010). A flow chart of how the AVOID system works is presented below in image 2. The United Kingdom’s largest airline EasyJet was the first to trial the AVOID system with initial installation on 12 planes beginning earlier this year at a cost of £ 1 million for development and installation. Although it is costing a substantial amount per aircraft EasyJet are confident the costs will be substantially less once the technology is refined for further implementation and save the airline even more in the event of a volcanic eruption (EasyJet, 2011).

Image 2: AVOID function flow chart (Macrae, F 2010).

Conclusion

The dangers volcanic ash present for aircrafts have been realized far back as World War 2, however volcanic eruptions have never been considered to occur often enough with wide spread affects to warrant a volcanic ash tolerant aircraft design. The relatively small Eyjafjallajokull eruption in Iceland showed the economic costs volcanic ash can have on the aviation industry. Another Icelandic volcano called Katla historically has erupted within a year of every Eyjafjallajokull eruption, with past eruptions sending 10 times as much ash into the atmosphere (Sherwell, P 2010).
There is definitely a need for technology that enables aircraft to deal with volcanic ash; however research and advances in technology are still required to create a full proof ash avoidances or tolerant system, and will require substantial government funding. But with evidence that more and larger eruptions are likely to occur in the future it will be a hard problem to ignore, and without technologies like the AVOID system to keep aircrafts in the air during a major eruption, the economical costs could be far greater than those seen in Europe with the Eyjafjallajokull eruption.

References

• Sherwell, P 2010, “Iceland volcano: an eyeful of Eyjafjallajokull”, the telegraph, viewed 25/03/2011, .

• Hayward, K 2011, ‘Under the ash cloud’, RAeS volcanic ash conference report, Aerospace international Volume 38, p. 18 – 21.

• Ellrod, G 2010, ‘remote sensing of volcanic ash’, NWA remote sensing committee, viewed on 22/03/2011, .

• Barnes, C 2011, ‘what is AVHRR’, National atlas gov, viewed on 22/03/2011, .

• Dinius, R 2010, “Statement of Roger Dinius flight safety director GE aviation”, mitigating the impact of volcanic ash clouds on aviation, Space and Aeronautics Subcommittee Committee on Science and Technology, Viewed on 24/03/2011, PDF download .

• International volcanic ash task force (IVATF), 2010, perspective on aircraft airworthiness when operating in airspace containing volcanic ash, viewed on 24/03/2011, PDF download .

Norwegian institute for air research (NILU), 2010, “Volcanic attention is erupting at NILU”, viewed on 24/03/2011, .

• EasyJet, 2011, “EasyJet unveils ash detector to end large scale disruption”, EasyJet corporate home, viewed on 25/03/2011, < http://corporate.easyjet.com/media/latest-news/news-year-2010/04-06-2010.aspx>.

• Macrae, F 2010, “EasyJet unveils infrared ash detector that will allow pilots to steer around volcanic debris”, Mail online, viewed on 25/03/2011, .

• Cover image by Terge Sorgjerd, 2010 “Eyjafjallajokull volcano” .