Cruising in a 747 losing air speed unless flaps are maintained

Hi all: Hace a random question on the behavior of a both a 747-200 & A380 from LAX to SYD. I’m fairly new to the community so I apologize if I posted this in the wrong spot but I have a quick question I wanted to ask. I was flying both a A380 and a 747 and both of those aircraft seem to lose airspeed midflight as well as altitude with the aircraft intermittently stalling. The only fix was to keep flaps at 10 during criuise. I wasn’t sure if this is normal procedure. It’s my first time trying this aircraft after flying the 787 and 777. When I retract the flaps, the aircraft seems to lose airspeed, lift and altitude. Any thoughts? I was flying against an 80 not headwind, I’m not sure if that added to the problem. Please educate me, I’m just trying to understand and learn.

Thanks!
Nick

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Hey Nick! Welcome!

First of all, flaps should not be used at higher altitudes.

Have you tried step climbing yet? If you climb to a certain altitude, burn off some fuel, then climb again, it’ll be way easier to get up to your desired cruise altitude without stalling.

Check this tutorial out:

If this doesn’t work, it probably means you have a bit too much weight for your plane to climb up to a high cruising altitude. :)

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This belongs in the Support category.

Welcome to the forum! I’m sure you’ll see forum help in the comments soon.

Welcome to the forum! I’d suggest checking your weight and balance before you take off. A heavier aircraft will have a harder time flying at higher altitudes. Try loading your plane a little lighter or using a website like simbrief.com to plan flights. Hope that helps and good luck!

Yes, this will have an impact. Normally you’ll have to cruise at a lower altitude, and maybe have the engines up higher.

When you retract flaps, lift is reduced but it also reduces drag, so it should be increasing speed. As already mentioned, having a tailwind isn’t good - it means that your aircraft will be less responsive and will stall at a higher speed. Try flying into a headwind and climb slower, making sure you’re at a sufficient speed.

This was happening to me in the 747-8 where the aircraft was also making a figure 8 pattern going left and right up and down.

I never had this issue. When you reach 10,000ft climbing, lower you vertical speed to 2,000ft and increase your airspeed to around 280kts so you have some speed while climbing. Keep decreasing your vertical speed as you get close to your cruising altitute, this is what I do. And as others said, do step climbing, stay at around 32,000ft for like half the flight, then keep climbing.

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A head wind isn’t going to cause you to loose lift.

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Where do you guys come up with this stuff? Totally inaccurate.

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Step climbing is your answer. Initially climb to around FL290 and maintain it until your weight drops enough to climb higher, I tend to climb in 2k intervals every hour until I achieve my required level.

Goodness gracious now Ive heard it all. Headwind lowering lift? No no no. The headwind will impact your GS yes but it will not affect your TAS because your AP is set to TAS. Regarless of what the wind speed is you will still be maintaining the same TAS with AP.

Your A/P is set to KIAS not KTAS.
IAS is indicated airspeed what you read on the gauge.
CAS is indicated airspeed adjusted for installation errors.
TAS is calibrated airspeed adjusted for pressure altitude, and temperature.
Pressure Altitude is altitude read when the Baro is set to standard 29.92hg.

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Yes it will however not enough so that you need flaps with 0 V/S.

A tail wind in and of its self will never decrease lift. Decreasing of lift from a tailwind comes from that tailwind suddenly stopping, causing the IAS to drop therefore decreasing the airflow over the wing, and decreasing the lift. Same thing happens if you have a head wind and it stops. Or the most dangerous when then headwind turns into a tailwind.

The tailwind it’s self has no effect.

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Was talking about once you get up to cruise FLs in IF (FL280 transition form your IAS to Mach value). Not sure yet if what it is read as is CAS or TAS but I would assume TAS since there isnt any installation errors in a sim really.

Thanks all. Really helpful feedback. I was just including all that extraneous info just to give a run down; I think I was just over weight, was trying to push the range of the aircraft but it ended up being counterproductive. Again my apologies not posting on the right subject area. I thought “support” meant tech support. 😉Thanks again.

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Really? Because I was cruising in global with an 80kt headwind at FL340. I tried to climb more but stalled.

Great question I would check you speed it could be that

I’m 100% positive. Wind will effect your ground speed or effect lift when the wind suddenly changes. As this will result in a change in the airflow around the wing at that time. However if the wind is constant it has no effect on lift. You where either too slow or over weight as the OP.

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