|Start:||April 28, 1986 ||Observed|
|Stop:||May 27, 1986 ||Observed|
|Lava flow: ||
|Tephra plume: ||
|Central eruption: ||
|"Fire", "Glowing", or incandescence: ||
|MaxVEI: ||2 ||
|Duration: ||About 1 month ||
From Reeder (1989): "On 28 April 1986, pilot Thomas Madsen, President of Aleutian Air Ltd. at Dutch Harbor, observed an eruption plume from the summit of Mount Cleveland. His flight was from Dutch Harbor on Unalaska Island to Atka on Atka Island. He initially saw the eruption plume at about 1220 LT at a distance of 190 km as he was approaching Mount Cleveland from the E. Tom estimated that the grayish white plume reached an altitude of about 2,900 m, about 1,200 m above the summit, and it trailed off for kilometers to the SSE. Tom had to fly at s 2,300 m altitude when he reached Mount Cleveland because of a 2,100 m altitude cloud layer, which prevented him from getting a good look at the flanks of the erupting volcano. The light gray plume had definite dark streaks and swirls of ash. Passengers including Dutch Harbor residents Mary Belle and Glen Fretwell of Peninsula Airways Inc. flight, which passed the volcano at about 1345 LT, reported a 1,000 m high white to gray eruption plume over the summit of the volcano with an ash trail extending at about a 2,000 m altitude for about 20 km to the ESE. Passengers including Dutch Harbor residents James Dickson and Scott Kerr of a later Peninsula Airways Inc. flight, which passed the volcano at about 1900LT, reported that the eruptive activity consisted of a white plume that rose at least 600 m above the summit and that a trail of dark gray ash extended for at least 40 km to the ESE.
"Hap Hayden, Ron Saylor, Dave Weyl, and Captain Emil Lindal observed eruptive activity of Mount Cleveland from their ship, the Blackhawk, on the morning of 27 May 1986. The Blackhawk had just delivered supplies from its cargo barge at Nikolski of Umnak Island. The wind had come up to 35 km/hr out of the N at 11 degrees E, so the Blackhawk with its cargo barge and landing craft at tow headed to the lee of Chuginadak Island for the purpose of loading its landing craft. At about halfway to Chuginadak Island at 0100LT, about 35 km E of Mount Cleveland, Mate Hap Heyden could see a glow from the top of Mount Cleveland. He was also able to detect sulfur fumes. At about 0235LT, the Blackhawk anchored in a cove on the S side of Chuginadak Island that was 12 km ESE of Mount Cleveland. Hap was able to recognize an approximate 60 m diameter crater on the ESE summit region of Mount Cleveland. The crater was oriented such that he could see the back inside wall of the crater. He could see incandescent lava shooting up to about 30 m above the crater that then was falling back into the crater. Dave Weyl was also able to recognize an approximate 10 m wide incandescent zone that extended from the crater down the SE side of the volcano by at least 100 m. Most likely this was a lava channel. To Dave, the glow from the crater was pulsating. At about 0450LT, the Blackhawk headed SE. Ron Saylor then detected a fog-like cloud, which irritated his eyes and throat. They did not get out of the volcanic cloud until they were S of Herbert Island, which is about 28 km SSW of Mount Cleveland. No ash was detected on the boat during this entire experience.
"At 1845LT 3 July 1986, pilot Tom Madsen observed a 100 m vertical white plume over Mount Cleveland while he was flying to Atka from Dutch Harbor.
"Pilot Tom Madsen and J.W. Reeder flew within 35 km N of Mount Cleveland on 10 July 1986 at about 1845LT and again at 2115LT. Only minor amounts of steam were rising from the SE top of the volcano, but the top 250 m of the volcano was black. In contrast, the nearby Carlisle Island was completely white with snow and the rest of Mount Cleveland was white with snow."