Cathay Pacific Asia Miles - Here we go again: Nasty Winds

I got into HKG last night on CX879 from SFO. Brutal winds forced us to tech at TPE and wasn't until past 8:30 pm that we landed in HKG. What got me curious was that the tech stop was not announced until 2 hours after we tookoff from SFO. So my question is did the folks in the cockpit not expect the tech stop before takeoff or they knew in advance they weren't going to have enough fuel to make it nonstop to HKG but forgot to announce it while the plane was still on the ground? I am not really sure how they forecast and how far in advance they forecast tech stop but that's what happened yesterday.

Oh yeah today's CX879 is also scheduled to tech in TPE and winter is just around the corner and there will be more in the coming months. How costly are these 747 tech stops anyways?

If you have ever lived in SE Asia you will know that weather changes here way faster than most places and weather systems have a habit of suddenly changing direction so by the time the flight is on its way they often have to re calculate and safety ditactes take no chances on CX, now if it was CI they would be seeing how close they can get to TPE on fumes and gliding !!!!

If you have ever lived in SE Asia you will know that weather changes here way faster than most places and weather systems have a habit of suddenly changing direction so by the time the flight is on its way they often have to re calculate and safety ditactes take no chances on CX, now if it was CI they would be seeing how close they can get to TPE on fumes and gliding !!!!

But.....the AIRLINE makes the DECISION on how much CARGO they're
going to carry, has nothing to do with mother nature. IMO the flights from the US west coast to HKG in the winter months make far too many 'technical i.e....."we need more gas cause the airplane is too heavy. " stops.
Cargo generates alot of revenue for Cathay , much more than the cost of re-accomodating a few passengers that have missed connections.

I don't get it. UA has a SFO-HKG flight (UA869) with scheduled timings almost similar to CX879 but on the two days mentioned where CX879 techs in TPE, the UA flight is making it nonstop and only several minutes late. The UA flight like the CX one is also using the 744. So why is the UA flight having no problems while the CX one needs to tech? Afterall winds are winds and whoever is flying in it will get affected. Are there significant tech specific differences between CX's 744s vs UA's 744s? :confused:

But.....the AIRLINE makes the DECISION on how much CARGO they're
going to carry, has nothing to do with mother nature. IMO the flights from the US west coast to HKG in the winter months make far too many 'technical i.e....."we need more gas cause the airplane is too heavy. " stops.
Cargo generates alot of revenue for Cathay , much more than the cost of re-accomodating a few passengers that have missed connections.

And before someone says 'they couldn't have known about the winds" along their route.....pilots have tremendous resources available to them, the most accurate being a simple analysis of the same flight 12 or 24 hours before. Weather systems do change but not that fast, in particular the upper winds.

IIRC, there used to be a CX cargo flight about the time of CX879. It is a possibility that the flight was cancelled and that CX879 also carried cargo. Perhaps the pilot calculated that there was enough fuel, but decided that it would be too marginal after getting updated data on weather.

If you have ever lived in SE Asia you will know that weather changes here way faster than most places and weather systems have a habit of suddenly changing direction so by the time the flight is on its way they often have to re calculate and safety ditactes take no chances on CX, now if it was CI they would be seeing how close they can get to TPE on fumes and gliding !!!!

No offense, but I highly doubt this is the reason (or even factually correct).

I don't get it. UA has a SFO-HKG flight (UA869) with scheduled timings almost similar to CX879 but on the two days mentioned where CX879 techs in TPE, the UA flight is making it nonstop and only several minutes late. The UA flight like the CX one is also using the 744. So why is the UA flight having no problems while the CX one needs to tech? Afterall winds are winds and whoever is flying in it will get affected. Are there significant tech specific differences between CX's 744s vs UA's 744s? :confused:

Yes. CX's 744 will be quite a few tonnes more heavy. The IFE in every seat, and the seats themselves will be heavier than UA's

If you have ever lived in SE Asia you will know that weather changes here way faster than most places and weather systems have a habit of suddenly changing direction so by the time the flight is on its way they often have to re calculate and safety ditactes take no chances on CX, now if it was CI they would be seeing how close they can get to TPE on fumes and gliding !!!!

For the past two or three years, CI even decided to let flight 007 (LAX-TPE night time flights) making scheduled technical stop at ANC due to the heavy payload and strong head wind in the winter (usually between December and February). If my memory is right, CI's trans-pacific flights (ex. LAX) sometimes make technical stop at KIX or OKA in winter.

I got into HKG last night on CX879 from SFO. Brutal winds forced us to tech at TPE and wasn't until past 8:30 pm that we landed in HKG. What got me curious was that the tech stop was not announced until 2 hours after we tookoff from SFO. So my question is did the folks in the cockpit not expect the tech stop before takeoff or they knew in advance they weren't going to have enough fuel to make it nonstop to HKG but forgot to announce it while the plane was still on the ground? I am not really sure how they forecast and how far in advance they forecast tech stop but that's what happened yesterday.

Oh yeah today's CX879 is also scheduled to tech in TPE and winter is just around the corner and there will be more in the coming months. How costly are these 747 tech stops anyways?

Typically the pilots would know its a possibility but leave the decision open.

Since I'm a commercial pilot, however not for an airline, let me add my two cents.

A lot of things are dictated by air traffic control. It is possible the UA flight got their clearance first, and was given priority in a "bad weather" situation where if 100% of the incoming flights were allowed to land, the delays would back everyone up by several hours. So air traffic control institutes "flow control" and its very possible due to the fuel situation, they can't have your flight circling for 1.5hrs and/or your pilots feel it would be safer to divert to TPE and wait.

On shorter flights say inside the US, SFO-DEN, if DEN has flow control, often they just won't let the aircraft leave SFO. That luxury isn't afforded by a flight from SFO to HKG as its such a long flight, they might as well get started and hope the weather forecast is wrong.

It could be CX company policy and each airline has their own policies. If more than two aircraft have done more than two go-around's in the past 30 mins due to high winds it might dictate CX divert and wait it out. For all you know, the UA flight was delayed after having made 2 attempts at landing and made it on the third attempt.

Also, as someone else pointed out, weather can change very rapidly. Airplanes are certified with a "maximum demonstrated crosswind" in which they can land. Say its 30kts for the 747. Maybe it was 20kts when UA came in, and went upto 33kts when your flight came in, which would result in your flight not legally being able to land.

We can't blame CX at all for the diversion to TPE. We don't have enough information to decide what happened on the flight deck that let to that decision, but suffice to say, it was done in your best interest because diverting, waiting on the ground at TPE and flying to HKG costs CX money. There is no possible way the diversion helped CX because now it also hurt their on-time performance.

I'm not saying UA is an unsafe airline, but its possible their company policies regarding landing in adverse weather conditions are more skewed towards on-time perf and making money.

Anyway, too many factors to consider and unless we speak to the pilots of the UA and CX flights, we'll never know.

I don't get it. UA has a SFO-HKG flight (UA869) with scheduled timings almost similar to CX879 but on the two days mentioned where CX879 techs in TPE, the UA flight is making it nonstop and only several minutes late. The UA flight like the CX one is also using the 744. So why is the UA flight having no problems while the CX one needs to tech? Afterall winds are winds and whoever is flying in it will get affected. Are there significant tech specific differences between CX's 744s vs UA's 744s? :confused:

Since I'm a commercial pilot, however not for an airline, let me add my two cents.

A lot of things are dictated by air traffic control. It is possible the UA flight got their clearance first, and was given priority in a "bad weather" situation where if 100% of the incoming flights were allowed to land, the delays would back everyone up by several hours. So air traffic control institutes "flow control" and its very possible due to the fuel situation, they can't have your flight circling for 1.5hrs and/or your pilots feel it would be safer to divert to TPE and wait.

On shorter flights say inside the US, SFO-DEN, if DEN has flow control, often they just won't let the aircraft leave SFO. That luxury isn't afforded by a flight from SFO to HKG as its such a long flight, they might as well get started and hope the weather forecast is wrong.

It could be CX company policy and each airline has their own policies. If more than two aircraft have done more than two go-around's in the past 30 mins due to high winds it might dictate CX divert and wait it out. For all you know, the UA flight was delayed after having made 2 attempts at landing and made it on the third attempt.

Also, as someone else pointed out, weather can change very rapidly. Airplanes are certified with a "maximum demonstrated crosswind" in which they can land. Say its 30kts for the 747. Maybe it was 20kts when UA came in, and went upto 33kts when your flight came in, which would result in your flight not legally being able to land.

We can't blame CX at all for the diversion to TPE. We don't have enough information to decide what happened on the flight deck that let to that decision, but suffice to say, it was done in your best interest because diverting, waiting on the ground at TPE and flying to HKG costs CX money. There is no possible way the diversion helped CX because now it also hurt their on-time performance.

I'm not saying UA is an unsafe airline, but its possible their company policies regarding landing in adverse weather conditions are more skewed towards on-time perf and making money.

Anyway, too many factors to consider and unless we speak to the pilots of the UA and CX flights, we'll never know.

I think what the OP meant was that the CX flights were landing in TPE before heading on to HKG as opposed to what (I think) you said about crosswinds and go-arounds since crosswinds and g/a's mean the flight has been to HKG first and then flown on to TPE. I'm sorry if I misunderstood, but just my $0.02.

Right, I understood that part. I mean CX might have received reports from ATC about flights landing at HKG going around, aborting landing due to strong winds, etc. If its an official PIREP (Pilot Report), CX can use it to make their decision whether to divert to TPE before even getting to HKG.

I think what the OP meant was that the CX flights were landing in TPE before heading on to HKG as opposed to what (I think) you said about crosswinds and go-arounds since crosswinds and g/a's mean the flight has been to HKG first and then flown on to TPE. I'm sorry if I misunderstood, but just my $0.02.

Yes, but the issue is not strong crosswinds on landing, it's strong headwinds across the Pacific... The divert is due to insufficient fuel.

It was insufficient fuel. It was too early to tell how the crosswind was 12 hours before arrival.

The flightplan had already submitted before the flight leaves and that means the dispatch in HKG had already decided to have a tech stop in TPE. I would think the pilot just wanted to announce later. Cargo is not an issue here as CX will offload cargo first when there is a payload issue(I know this coz I am in the freight forwarding industry). During the winter season, SFO and LAX flight will not be able to take any cargo as the payload is always bad. With tech stop means there is not enough payload even not taking any cargo.

Sometimes they do announce tech stops during check in, this happened to me about a year ago. In regards to cargo, I don't know how much they bring westbound because as I know, most west bound cargo runs are loss leaders. Although... the cargo that gets put in a passenger plane does cost more due to it being a direct flight.

This was discussed in the spring when it happened several times (rather late in the season, and including to me).

At check-in (the LAX 744 afternoon flight) notices said we would be stopping at ICN. Many hours into the flight it was announced we would now stop at TPE. We did, never went to a gate, just gas-and-go. Crew was delighted since ICN stop meant a crew change and they wouldn't get home that night.

There was speculation in the spring thread that the engine performance is also a factor in UA vs. CX range with headwinds -- P&W vs. RR IIRC.

Regarding why CX had a tech stop in TPE and UA did not, I remember reading from another post that a flight that continues beyond HKG would have higher priority in such situations. The UA flight which continues to Singapore (or is it Ho Chi Minh) would have priority, wheras CX879 with final destination in HKG would not. Of course, this logic does not make sense since it is assumed the final destination of all passengers on CX879 is HKG.

Can somebody confirm ?

The flightplan had already submitted before the flight leaves and that means the dispatch in HKG had already decided to have a tech stop in TPE... .

I am both a commercial pilot and frequent CX passenger on the SFO-HKG route. Flight plans are totally flexible - consider them more like a proposal than a plan. They are changed routinely in-flight by both the pilots and ATC.

One part of every flight plan is the alternate - where you land if conditions change and you can't land at your destination. Alternates can also be changed any time. Legally the aircraft must land at the destination with enough fuel to fly from the destination to the alternate and then for 45 minutes longer. Weather at the alternate has higher requirements than weather at the destination because the alternate must be a sure thing. If CX plans Guangzhou as the alternate and then the Guangzhou weather goes bad the next alternate may be too far to land legally in HKG even if HKG weather is passable. That's very simplified but it gets the point accross that there's a lot going in to the decision where to land and it can't all be guaranteed 15 hours in advance.

As a passenger I've been on several CX SFO-HKG flights where they've announced a techinical in TPE but in every case we're actually made it to HKG. Throughout the flight the pilots keep tabs on their fuel situation and the traffic and weather at the destination and alternate and then make a call en-route to stop or not.

Finally I think the points above about the cargo tradeoff are true. CX could choose to leave cargo behind in exchange for fuel and guarantee making it to HKG. UA seems to be making the decision to carry more fuel. A UA diversion to TPE could cause major crew problems since they don't have backup crews there. CX can get a new crew to TPE easily or perhaps has them stationed there. So yes, I think it's a business decision to chance the stops in TPE.

The flightplan had already submitted before the flight leaves and that means the dispatch in HKG had already decided to have a tech stop in TPE. Wrong. www.flightaware.com shows how the flightplan filed with the FAA for that day was for HKG. PaulSEA1 hits it in the nail.

Both CX873 and CX879 for 12/22 departures are stopping in TPE again. Is SFO-HKG close to the maximum 744 range?

Both CX873 and CX879 for 12/22 departures are stopping in TPE again. Is SFO-HKG close to the maximum 744 range?Don't understand the reason for your question; are you assuming that CX is adding the TPE stop for fun?

Headwinds on the shortest (great circle) route are up to 130KT tonight.

All I am asking is the about the maximum range of an aircraft and how close is it to it for a particular route. All aircrafts have maximum ranges and I was inquiring on the numbers of one of them so it will give me a better understanding on how operations go if their flying time for a particular route is prolonged.

If I had known those technical details, I would not have asked the question in the first place. Understand?

All I am asking is the about the maximum range of an aircraft and how close is it to it for a particular route. All aircrafts have maximum ranges and I was inquiring on the numbers of one of them so it will give me a better understanding on how operations go if their flying time for a particular route is prolonged.

If I had known those technical details, I would not have asked the question in the first place. Understand?

No need for such a rude response in this forum. A google search will solve your question in less time it took you to write that. Type in "747 range". The first link that popped up when I searched is called "airliners.net," and on that page it says a range of roughly 7,670 nm for the ER non-freighter version. HKG is something like 6,900 from SFO. So yes, it seems to be pushing the envelope. Like many of the frequent posters on this forum, I am one of the many who have done a tech stop SFO-HKG while flying both on CX and on SQ.

All I am asking is the about the maximum range of an aircraft and how close is it to it for a particular route. All aircrafts have maximum ranges and I was inquiring on the numbers of one of them so it will give me a better understanding on how operations go if their flying time for a particular route is prolonged.

If I had known those technical details, I would not have asked the question in the first place. Understand?Ah, try www.boeing.com. You will find all sort of performance data based on gross weight, density altitude, runway lenghts etc. Then you can model in requirement for fuel to reach alternates, ETOPS restrictions, that aprticularr night's PACOT tracks, etc. etc.

Have fun! ;)

Both CX873 and CX879 for 12/22 departures are stopping in TPE again. Is SFO-HKG close to the maximum 744 range?

SFO-HKG is ~7000 miles.Well within the range if a 747-400 under normal circumstances (winds and weights).

Depends on route, head winds, number of passengers, amount of luggage, cargo and the amount of time margin in case of bad weather at destination (or heavy traffic) and distance to alternate airport (safety). They are NOT stopping at TPE because they want to.

Regarding why CX had a tech stop in TPE and UA did not, I remember reading from another post that a flight that continues beyond HKG would have higher priority in such situations. The UA flight which continues to Singapore (or is it Ho Chi Minh) would have priority, wheras CX879 with final destination in HKG would not. Of course, this logic does not make sense since it is assumed the final destination of all passengers on CX879 is HKG.

Can somebody confirm ?

Not a factor.