The luck was that the descent process below the invisible ash cloud cleaned enough ash off those turbine blades to allow the engine restart process to work while they still had altitude to recover- and then they ascended back into the cloud and stalled again but were close enough to an airport to glide in
the crew was clueless about the source of the problem
Typical understated British pilot announcement to the passengers, though! “Ladies and Gentlemen, this is your Captain. I’m afraid all the aircraft engines have stopped working. I trust this won’t cause you too much distress...”
What a story
“How far can we go with no engines?”
“Oh, not to worry. I am sure we will make it all the way to the scene of the crash. And we will likely beat the emergency vehicles by at least twenty minutes or so.”