WHENEVER there is volcanic ash in the skies, it is certainly no condition for an aircraft to fly. And the current shutdown of European airspace, which is costing the industry some $200M per day, is a wise decision made by aviation authorities and governments. And it may be quite a few days more before the go-ahead is given so that flights can once more take off from their respective airports. But low-altitude flights are taking place. Lufthansa Airlines flew 10 empty planes from Frankfurt to Munich (Saturday) just under 10,000 ft—way below the normal altitude—but out of necessity just to have the planes where they would be needed when the air restrictions are lifted, sometime soon they hope. Dutch airlines KLM is carrying out tests for low-altitude flights, in trying to get approval to do same with her fleet. The Swiss Air has done just the opposite; they are flying above the volcanic ash at about 36,000 ft. Do note that these are very risk-taking practices being employed by these airlines, as they are conducting flights outside of the normal parameters of altitude ranges and sometimes without instruments like radar, etc. But, as I said, it is out of sheer necessity due to the fact that this issue could prolong for quite some time into this new week. But the majority of commercial flying has ceased and European airspace has been virtually a ghost area; the last known closure of this magnitude was 9/11.
The industry is taking no chances, while at the same time they may be remembering June 24, 1982. British Airways Flight 9 was making its way to Auckland, New Zealand, with about four stop-over to other airports. Unbeknownst to the flight crew, the plane flew into airspace polluted by volcanic ash from the Mt Galunggung volcano. Radar did not pick up the ashes because they were very dry; radars usually pick up moisture in the clouds. A few minutes after, any pilot’s worst fears in the sky was confirmed: they began to lose power in each of their four engines, one after another. These engines push power to the plane so just imagine the confusion. The ash had entered the engines and melted. They had halted crucial processes in the aircraft’s engines, intended to keep the plane in the air and power being supplied all over. The oxygen masks dropped after the fourth engine was lost and passengers received one of the most famous messages—perhaps the most famous understatement of our time— a pilot had ever given his passengers, “Ladies and gentlemen, this is your captain speaking. We have a small problem. All four engines have stopped. We are doing our damnedest to get them under control. I trust you are not in too much distress.” Passengers immediately began scribbling notes to their loved ones.
The jet, after losing all its engines, had now turned into a mega air-glider. Planes cannot just fall out of the sky after losing all their engines. At those high altitudes, they simply glide through the airspace while dropping at fixed rates after gliding for a certain distance. The crew quickly calculated that their plane could’ve only glided some 23 minutes more after which it would’ve reached the ground, or crash. They immediately tried the engine restarting procedures over and over.
As the engine cooled from not being in operation and the aircraft descending out from the ash clouds, the molten ash solidified, enough to break off and fall out of the engine; that allowed cool air to pass through, allowing a successful restart. The pilots got back all four of their engines one after the other, allowing power to the aircraft, which made a successful landing, though without any sight from the windscreen due to ash cover.
Not only can aircraft lose all their engines during these ash covers, but due to poor vision because of the contaminated air quality, mid- air collisions with other planes are very possible. Although pilots have the on board air collision indicator which would normally sound a minute or two prior to a pending collision with another aircraft, this is too much of a gamble for this industry which is responsible for the safety of the flying thousands each and every day.
On December 15, 1989, KLM found itself in a similar incident, but was able, too, to make a successful landing.
It is though; too risky to have these pilots fly the aircraft into these clouds, knowing fully well they will knock out all the engines. Engine restarting procedures are not cock sure contingency operations and do not guarantee success due to the differing dynamics of volcanic ash and their unique compositions. The industry knows this and knows, too, that above anything else, passengers’ lives and their safety come first.