Without taking the time to verify what he actually said - this particular prophecy isn't particularly impressive. He doesn't give a date, simply saying 'Friday'. I'd assume that meant this Friday, but lets give him the benefit of the doubt and assume he meant any Friday. He didn't mention a place, so all we have is a plane accident on a Friday involving a family. He actually said 'families' inside a plane - so any private jet which crashes with at least one family aboard on a Friday will do. He didn't say the family would die, so this is irrelevant to the success of his prediction.
Let's see how unlikely this event is. According to the Aircraft Crashes Record Office in Geneva, which attempts to record every air accident involving a plane big enough to carry at least 6 people, the mean number of annual accidents in the previous five years was 165.2. Assuming an accident is just as likely to happen on one day of the week as any other, this means we'd expect approximately 23.6 crashes on Fridays in the average year (without checking this, I'd expect Fridays to be a more likely day for a family's private jet to crash - it's the start of the weekend in much of the world, just when a family might be jetting off for a couple of days on their favourite Pacific / Carribbean island resort).
Each year has either 52 or 53 Fridays, so if we have an air accident on 24 Fridays; approximately every other Friday will expect to see an air crash. The fact that a family will be involved in an air accident in a private jet at some point in the future on a Friday is a pretty safe bet - note that it wasn't till five Fridays later that he managed to find an event that matched his prediction.
More later! I'm at work.
Edited by caffeine, : minor grammar and style changes