Approaching Stall? B777F

Hi all,

Flew from KLAX to SBRB on the DHL livery of the B777F. Cruise was set at FL390. I was flying fairly heavy but not maxed out.

My problem is this, cruise speed was GS 474kts. Why when I was approaching FL360 did the aircraft begin to lose speed, N1 hit 101% and subsequently lose altitude? Never had it before but if I leveled back off at FL330 the speed came back up and and N1 back to 84%. This happened at every stage of flight, even after fuel dump and load was down to 60%

I’d set my device down for a long haul, lucky I checked as I was beginning to approach stall when I realised.

I was under the impression that more weight increased drag so higher altitudes were better. But very confused why the aircraft couldn’t physically get up that high without stalling.

Any advice appreciated! Thanks

You are too heavy to climb that high. Start off around FL330.

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Check out this guide on step climbing

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Thank you: sorry for such a basic question. I assume air density at high altitudes inhibits lift.

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That is somewhat correct, you’re just missing a part of the equation. Flying this high, this heavy, means that your engines needs to run at a higher power setting, but air at FL390 isn’t as dense as it is at lower FLs.
You reached your aircraft’s coffin corner (look it up, it is fascinating)

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