FL38 to FL27 and back to FL38

[armchairpilot94116]

Flying on EVA's 777 enroute to TPE at night. Three hours from TPE we descended from FL38 down to FL27. We were flying over clouds at around the FL27 level but far above them and with little turbulence. But it got bumpy soon as we got to cloud tops at FL27 and then engines were gunned and we climbed quickly back to FL38.

I was wondering what was happening as we were still three hours flying time from TPE and way too soon to start our descent.

Wonder what was going on?

[Talkdownman]

FL38? FL27? Gosh, that's low...

[chevvron]

Do they have altimeters set to 1013 in passenger seats nowadays?

[Load Toad]

Come on - passenger asks a simple question out of curiosity in the correct forum and up jump two clever & witty types with a sensible answer. Well done.

[mad_jock]

Do they have altimeters set to 1013 in passenger seats nowadays?

Yep piped through the entertainment system. Might not be linked to the alt though may only be a GPS alt.

I don't have aclue why they would do that.

[Hotel Tango]

Might have been very strong headwinds at 380 and the possibility of significantly less at 270 (thus reducing flight time). Perhaps it didn't pan out as expected and together with the increased discomfort for the pax from the turbulence they decided to go back up. I don't think it would have been an ATC level change due to traffic, certainly not 11000 feet's worth!

[de facto]

Where did you take off from?

[DavidWoodward]

This place is like a children's playground sometimes. The OP asked a relevant question.

[armchairpilot94116]

SFO to TPE nonstop 77W March 7th, 2012 13hours 40 mins.


3 hours from TPE puts us not far off the Japanese mainland. We had been at FL38 for some time (according to in seat entertainment system route map info including / ground speed / height which I had been following the whole flight).

Normally I would expect us to start our descent about 30 mins from landing or perhaps 40 mins. But I didn't understand why we left FL38 down to FL27 in a matter of a few minutes down to the cloud mass.

After a few minutes being bumped around by surfing the cloud tops engines were gunned and we climbed back to FL38 in short order.

I just didn't understand why that was done? Training?

I've not experienced that before . I have flown quite a lot (in the back) and generally like to keep abreast of what is happening.

[Hotel Tango]

Armchairpilot, refer to my post above. There are at times notoriously high winds in that area (experienced them myself). It is not unusual for aircraft experiencing significantly strong headwinds to descend to lower altitudes where the winds may nor be so strong. That is the most likely reason, and certainly not "training" (where did you get that from?).

[armchairpilot94116]

Yes I suppose very strong headwinds at that level would be a great reason to leave that level and then come back up again for best cruise as soon as possible. Especially a 77W on a 13 hour and 40 mins nonstop, the need for best cruise is clear.

I was thinking since EVA is well known as a "training airline" maybe they were doing some training . And if that was at all even allowed on line and how much training exactly IS allowed on line?

We were doing fine, didn't notice any decrease in ground speed and then we decided to head down to the cloud mass where we got bumped around. Then we headed back up. So made me wonder.

Course if they were advised by ATC to do what they did due to expected winds aloft, well thats a great reason.

[chevvron]

You would make a lot more sense if you used the correct nomenclature when referring to flight levels; FL38 is approx. 3,800 ft whereas I believe you meant 38,000ft which would be FL380.
Also not everyone understands IATA designators including me; I'm aware SFO is possibly San Francisco, but where is 'TPE'?

[Load Toad]

I think chev you are being picky - anyone can Google the airport code if they aren't sure (it takes seconds to do) & even I could understand he meant 38,000.


Let me google that for you (http://lmgtfy.com/?q=iata+code+tpe)

[armchairpilot94116]

Apologies. 38,000 down to 27,000. Sorry. San Francisco to Taipei Taoyuan International Airport.

[mad_jock]

I have never flown in that part of theworld but I seem to remember there is a Jetstream that goes up the coast of Japan then heads out into the pacific.

To be honest it could be a multitude of things from permission to enter airspace enroute which was then sorted in the decent, to a technical issue which meant they had to drop down to below FL300 which then self healed so they could go back up again. Wind as mentioned. The wx might have been bad at destination and "company" may have instructed them to divert to Japan then changed there minds.

The only people that are going to know are the crew on the day.

[armchairpilot94116]

Yes no doubt. Japan does seem to have more then its share of turbulence and wind and clear air turbulence. We were bouncing about a bit, but just light to moderate chop and I was happy we were above the cloud mass which we had been flying over for several thousand miles. Spent much of the first part of the flight at around 33,000 feet (understand the fuel need to be burned off before a higher cruise can be economical) then later up to 38,000.

We seemed to gently decrease altitude (no speed brake) from 380 down to 270, right on top of the cloud mass. And I was thinking "oh great, we are going to surf this for three hours until Taipei". Thought maybe it was traffic or something. But it got worse the bouncing around. Then suddenly I hear the engines roar for a few minutes and i watched the altitude climb on the route map. And was surprised we were right back where we were at 38,000.

And then the funny part was 30 minutes to landing came and went and the cabin crew didn't yet come to do a final check if passengers are belted in and seats upright. And I was wondering if we were going to hold over Taipei.

Then if I remember correctly right around 25 minutes to landing the speedbrakes came on and the CC passed by quickly to ensure seatbelts on and seats upright and we descended quite rapidly to a nice landing in the wet at Taipei on schedule at about 1030pm local time.

Seemed a rather quicker descent then usual.

Did I say I was a nervous flyer ? :}

[mad_jock]

Don't worry pilots are very incline not to strap an aircraft to thier backsides if they think that the number of takeoffs isn't going to equal the number of landings in the techlog afterwards.

And to be honest what a pax thinks is moderate turbulence isn't actually. If the CC were still moving about it was light. Sever turbulence has things lifting and damage to the aircraft. Moderate everything is secure and CC strapped in and pax using the sick bags. Which is why its always sensible to have your seat belt on even if its smooth.

Its sounds like there was some operational issues from either company planning or ATC.

I suspect the arrival runway was contaminated so they kept high to save fuel and when the runway got reported as just wet they had to get the height off quick and get in before it started chucking it down with rain again and they couldn't land. The americans have a dispatcher who speaks to the crew and keeps an eye on whats happening enroute and arrival and the slow decent was maybe setting up for a divert but then the decision was made to continue so they climbed up again. I suspect a divert into Japan logistically is far easier and cheaper than continuing down and having to divert in somewhere closer which may produce visa issues with pax and flight clearances etc to get out again.

Honestly nothing to worry about, all part of the job of being a pilot and dealing with mother nature.

[armchairpilot94116]

Fair assessment. This flight has been known to divert to Osaka on occasions when headwinds have been stronger then expected on its long run across the Pacific and they would be below minimum fuel for the three hours from the Japan Mainland to Taiwan (again over water). Okinawa would have been another good diversion airport once much past Osaka.

[Hotel Tango]

mad_jock, you might be a pilot but I'm led to believe that you're not familiar with the area and the type of winds experienced there. Furthermore, ATC would not issue an 11,000 ft level change 3.5 hours from destination unless it was requested by the crew. I have myself flown in the area and experienced descent from FL370 to FL270 and then later back up to FL370 because of an area of significantly strong headwinds.

Armchairpilot94116 now confirms this with This flight has been known to divert to Osaka on occasions when headwinds have been stronger then expected .

I still strongly believe that was the issue.

[mad_jock]

I did state that if you had read my posts.

Anyway they got there and armchair can be reassured that everything was above board and he was in safe hands.

[Hotel Tango]

:ok: Roger, sorry about that ;)

[armchairpilot94116]

Thanks guys, next time that happens I will have been better informed. I am one of those flyers who don't care so much about the service. More about the flight itself. If I could I would fly myself around in my own GV.
:8

[mad_jock]

If its any help I think so would most pro pilots as well. :ok: