The block of ice fell from another plane that was flying 1,000 feet above the jet while it was cruising at 35,000 feet.
It completely cracked up the two-inch thick windscreen, which is built to withstand extreme force and is similar to bulletproof glass.
The incident has been described as a ‘one-in-a-million’ chance and left some 200 passengers stranded over Christmas instead of being able to make it back to London.
Thankfully, the plane was able to make it to San Jose after the in-flight incident, but it then couldn’t take off again for a while, meaning that the passengers waiting for it were left kicking their heels.
Their flight was rescheduled, but a plane could not be diverted from Jamaica to take them, so they finally departed some 50 hours later on Boxing Day, meaning they missed the entirety of Christmas Day.
At the beginning, the passengers were told that they were looking at a 90-minute delay, but obviously that overran by a long distance when it turned out that the plane would require specialist repairs.
One pair of passengers were on their honeymoon at the time and had hoped to make it to Edinburgh in time to spend Christmas with their family.
Dr Jo Mitchell told The Independent: “My husband is part-Icelandic and his family who live in Edinburgh celebrate Christmas on December 24.
“We were desperately trying to find a connecting flight at this point that would get us there in time to not miss his family Christmas.
“The BA app was saying something vague about the flight being delayed to the next day. The flight time however, only showed a four-hour delay.
“We had received no information via email or message so we hoped it was just a glitch.
“We dropped our car and continued to the airport, desperately hoping it wasn't true."
Soon, it became clear that it was true.
Dr Mitchell added: “At this point we were devastated - realising we would miss Christmas with both of our families.
“People in the queue were begging the staff for an alternative, some angry, some crying.
“People were breaking down in tears as this was the first they had been told that they were going to miss Christmas.”
A spokesperson for British Airways said: “We would like to send a heartfelt apology to the customers on this flight, who have had their Christmas plans ruined.
“We will never fly an aircraft unless we feel it is completely safe to do so, and on this occasion, our engineers were unable to clear it to fly.
“Since then, our teams have been working behind the scenes to do all they can to ensure an aircraft is ready at the earliest opportunity to bring customers to London.
“We appreciate the patience and the understanding of our customers and our engineers and crew colleagues who have also done all they can to assist.”Featured Image Credit: Alamy (stock)