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Mountain Flying – Limit to 90% of Max Gross Weight?

Asked by: 3160 views Aerodynamics, General Aviation

Hello,

I've read several instances where it has been advised to limit aircraft loading to 90% of max gross when flying in the mountains. Does this "conventional wisdom" apply in the case of a TURBOCHARGED aircraft? Obviously the turbo will allow the engine to develop sea-level power at a high-altitude takeoff BUT I also realize the prop and wings are not nearly as efficient. Curious for people's thoughts on this topic!

Thanks

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1 Answers



  1. Mark Kolber on Aug 31, 2017

    I think you’ve answered your own question. The weight reduction will result in some improvement in performance in a turbo, but not as much as in a normally aspirated piston airplane.

    If you look at your performance tables, reduced weight always gives a performance boost. A piston at high D-alt is typically operating near its performance limits, particularly for takeoff and climbs. The 90% recommendation is a way to increase those margins. turbos will typically have larger margins to begin with.

    So, it’s a judgment call. Personally, I follow the 90% rule even in a turbo. I’ve found too many pilots who think a turbo solves all D-alt issues. I prefer to err on the side of caution.

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