Hi,

I recently flew round trip transpacific a month ago and discovered that the flight path were completely different from one another. On the outbound SFO-HKG (CX 879), our journey after takeoff from SFO took us through northern california coast, through deep into inland Alaska flying above near Mt. Mckinley, through the Bering Strait, through Eastern Siberia, then going southwest through Hokkaido/Japan, through Taiwan and then into HKG. We left SFO more or less on time but arrived into HK almost 1 hour behind schedule. Don't know if this flight path played the role?

On the return HKG-SFO (CX 872) we flew a basic across-the-pacific path. The only land we flew above was Taiwan and the remainder was above-ocean all the way until we began descending into SFO. For this flight, we ended up arriving 45 minutes ahead of shedule.

So why is it so northerly on the outbound and then a relatively straight southerly on the return?

Usually has to do with winds, I presume. Winds are stiff in the winter and spring and can cause delays even when you leave on time. Just be happy you didn't need a refuel stop. As for why different routes, I imagine the winds change slightly with weather patterns. Given the weather data available, the pilots calculate a flight path that will get there the quickest (also avoiding any storms), and this isn't necessarily a straight line.

One time I was op upped to J and a pilot was drinking a coffee. I asked him the same very question and his answer was: WIND, WIND, WIND.

Sometimes they'll go almost due west from SFO to HKG to stay south of the jet stream. Sometimes, they go way north of it. Coming east, everyone flies in the middle of it to get the tailwinds -- not unusual to experience ground speeds of 1100 km/hour + coming east.

In the winter, many LAX - HKG and even some SFO - HKG nonstops have to land in TPE or ICN for fuel account the headwinds and aircraft weight make it impossible to fly the entire distance nonstop..................

I fly this route monthly. The SFO people are lovely and the service itself excellent. BUT I find it irksome that CX 873 and SQ1 take off at about the same time but SQ1 usually gets in way ahead of us. Some time ago, one CX captain told me they fly faster. I suppose it's all about fuel these days.

Eastbound into SFO, either I am unlucky on my dates or something similar is happening despite the strong tailwinds. It seems to be much less frequent for CX872 to get in more than 15 mins early than it was last year. This has a knock on effect for pax because shortly before scheduled arrival, both Virgin and Qantas get in on the same wing of SFIT. The queues at immigration then take around 20 mins to get through, occasionally a bit longer. Previously, a 30 mins or more early arrival brought us to an empty row of desks, or just clearing the end of an Air France arrival.

Good point - Have taken SQ1 twice with CX taking of 5-10 minutes earlier and landing 10-15 minutes later each time.

Anyone got any ideas why? Does CX save on fuel this way (which begets the question why doesn't SQ simply follow CX?)

I've noticed the same thing...I'm usually on SQ, too, and whoever requests push first at SFO gets right-of-way (BR and CI also in the mix, so it gets tangled).

Still -- SQ consistently does well, and has fewer refueling stops in TPE during the winter. Aircraft weight, maybe?

Another suggestion: maybe because SQ 1 continues on to SIN? They need to prepare for the flight for a 0800 exHKG depature.