I was on that flight...
UA 901 (744 aircraft) was diverted to OAK today due to a malfunction in the instrument landing system, compounded by fog and fuel. I was on that flight. Here's my take on the story:
We were on our final approach to 28R at SFO in patchy fog. I've landed on this runway countless times, but when I looked out the window right before landing, I thought "holy $#?&, we're really close to the water." Sure enough, the pilot went full throttle, pulled up, and channel 9 went dead. Seemed like a missed approach. We circled around and missed our next approach as well. After this missed approach, the captain announced we were diverting to OAK. We landed at OAK, parked at gate 1 at OAK, but nobody was allowed to disembark, and to the best of my knowledge, no cargo was unloaded. Some maintenance employees came on board, and there was a constant stream of pilots and maintenance crew in and out of the cockpit. The bottom line (inferred from announcements and overheard snippets). Our ILS was malfunctioning, hence the dangerously low approach the first time, and the failure to land on a subsequent time in fog.
The ILS could not be repaired in a reasonable timeframe (especially now that the OAK maintenance facility is closed) so the options were
1. Wait 5-6 hours for border patrol to set-up an adequate passport control and customs operation
2. Refuel the plane, wait for the weather to improve to allow a visual landing at SFO, and fly across the bay to SFO.
The captain opted for #2, which yielded a 2.5 hour ground hold in OAK. Glad I was in row 15.
It was fun to be on an OAK-SFO flight (my first ever), and on a 747, no less. About 10 minutes of airtime. The FA's remained seated for the whole flight, but once we were on a final approach, the purser jokingly made a call for "flight attendants, prepare for arrival." Visibility was great at this point, and we landed pretty smoothly on the first approach. Too bad channel 9 was off for this segment as well.