Ash Clouds

Iceland’s Eyjafjallajoekull volcano and its ash cloud has been back in the news again as more flights get canceled. Hence, the Wall Street Journal recently had an interesting article (“Cloudy With a Chance of Danger: Airplane vs. Ash”) by Carl Bialik about aviation’s US$1.7 billion question: How much volcanic ash is in the air and how much is too much for an airplane engine? Bialik noted that cancellations have already cost airlines US$1.7 billion and they are increasingly lashing out at the statistical models that predict how much ash is out there and where it is. In fact, Irish airline Ryanair has gone so far as to say in a statement that the UK model of volcanic ash clouds is "substantially fictitious."

In a separate post for his blog (“The Numbers Guy: Carl Bialik examines the way numbers are used, and abused”), Bialik then noted that not everyone is critical of aviation authorities. However, he pointed out that predicting ash clouds remains a very hazy affair – along with how much ash is to much ash.

Hence, we would like to ask you our readers what you think about the response to the ash cloud: Are aviation authorities being overly cautious and conservative or has their response been just about right?  

With flights only now just starting to takeoff again in Western Europe, it might be a good time to revisit past incidents involving aircraft and volcanic ash which illustrate just how dangerous volcanic ash can be to aviation under certain circumstances. Both the Airline Biz Blog and Flight Blogger have recalled a 1982 incident involving a British Airways Boeing 747 that flew through volcanic ash over Indonesia while in route to Perth Australia. All four engines failed but the captain was eventually able to land safely in Jakarta and the incident eventually led to a network of volcanic ash advisory centres being set up to monitor and track volcanic ash clouds. You can learn more about the incident on Wikipedia plus the The Times of London has recently interviewed the Pilot of the aircraft for his thoughts and there is also an episode of “Air Emergency, Air Crash Investigation” that recreates what happened. 

In addition, another incident that involved a KLM Boeing 747 flight that flew through an ash cloud from a 1989 eruption of Mount Redoubt in Alaska is told on the website of the Aviation Safety Network. Luckily, the aircraft was also able to land safely with only minor damage.

If you are one of our pilot readers in Western European, we will assume that you are still probably grounded due to the volcanic eruption in Iceland. However and in case you have wondered how you might be able to fly through a volcanic ash cloud, Jon Ostrower has posted a link on Flight Blogger to a 1999 article in Aero magazine – Boeing’s technical magazine. According to Jon’s summary of the article, the following nine procedures are general recommendations for an encounter with a volcanic ash cloud:

1. Reduce thrust to idle immediately.
2. Turn the autothrottles off.
3. Exit the ash cloud as quickly as possible. 
4. Turn on engine and wing anti-ice devices and all air-conditioning packs.
5. If possible, start the auxiliary power unit (APU).
6. If volcanic dust fills the flight deck, the crew may need to use oxygen.
7. Turn on the continuous ignition.
8. Monitor engine exhaust gas temperature (EGT).
9. Fly the airplane by monitoring airspeed and pitch attitude.

Jon includes further details with his summarized recommendations as well as pictures. However and if you want to see just what type of damage volcanic ash can do to an aircraft engine, commenter AirShowFan has posted a link to a Discovery News article that includes inspection images of DC-8 engines and F-18 engines after a flight a volcanic ash cloud. After taking a look at all the pictures, all that we can say is that its probably a good idea to stay on the ground for the time being.