1 The giant plumes blasted into the sky by volcanoes may look like ordinary clouds, but they contain engine-clogging ash that can pose disaster for unsuspecting aircraft.
2 To avoid dangerous events like those that forced two airliners to land with engine malfunctions in 1982, a pair of federal agencies is launching a new volcano watch program for aviators.
3 The volcano alert project was announced Thursday by the National Oceanic and Atmopsheric Administration and the Federal Aviation Administration, although a formal start-up date was not set.
4 Over the years, major volcanic eruptions have spewed vast plumes of ash to high altitudes where it was spread widely by strong winds.
5 In one case in 1982, ash from Galuggung volcano in Indonesia caused engine shutdowns in Boeing 747 airliners on June 23 and on July 13.
6 Both planes were forced to land when their engines malfunctioned after being coated with the glass-like ash.
7 More than 20 volcanic eruptions have been reported beneath the North Pacific air routes between North America and Asia in just the past five years.
8 Active volcano areas include Italy, Greece, New Zealand, Indonesia, the Philippines, Japan, Alaska, the Pacific Northwest, Mexico, Colombia, Peru, Ecuador, Chile, East Africa, Hawaii and the Caribbean.
9 Volcanic ash plumes can spread as high as 60,000 feet and, especially at night, it can be difficult for a pilot to tell when a cloud is being entered.
10 In the new warning program, NOAA weather satellites, pilot reports and other sources of information will be used to watch for volcanic eruptions.
11 The U.S. Geological Survey and the worldwide Scientific Event Alert Network operated by the Smithsonian Institution will also assist.
12 While weather satellites are expected to be the primary source of information, scientists stress that in the early stages of an eruption it can be very difficult to tell the difference between ash clouds and ordinary water or ice clouds.
13 Heat imaging satellites should help in this area.
14 Once an eruption is detected, the FAA will be kept advised of the location, height and movement of ash clouds.
15 The Civil Aviation Organization of the United Nations will also be informed of volcanic cloud movement so it can advise airlines from other nations.
16 The advisories will report height and plume movement at two-hour intervals and will provide short- and long-range forecasts of cloud movement.

To avoid dangerous events like those that forced two airliners to land with engine malfunctions in 1982 , a pair of federal agencies is launching a new volcano watch program for aviators .
a pair of federal agencies
Which federal agencies?