Originally Posted by CaptainSandL
Does anybody know the L/D max (the ratio not the speed) for any version of the 737?
Fact - 767-200 is 17.9 per Boeing manual
Experience - 757 is cleaner. 767-200 at 20 DME needs about 200' more altitude(energy) than the 757 for a clean approach, with idle power to <1000' AFL than the 757.
Experience - S-80 needs slightly more and the 727 even more altitude(energy) to accomplish the same. I was told the 727 was 17:1 or slightly better.
737? IDK.
Almost all airliners have very similar glide ratios. For simplicities sake let's call it 18:1. 30,000' is 5 n.m. high. 5 n.m. x 18 = 90. Your altitude in thousands x 3 = gliding distance. 40,000' = 120 miles.
Speed? Holding speed. Per Boeing that is L/D speed. That's the speed I would use for my glide speed. At high altitudes the FMC generated airspeed is to low (KIAS/ECAS/MACH issues).
I've had several emails on this topic with Boeing engineers.
Sim experience - 250 kts at 7 mile final on the glideslope gets you to the runway. Perfect for 727 but more energy than you need for the 757/767(cleaner, ie better gliders). Maybe a slower speed (KIAS) is perfect but 250 has always worked in the sim. More energy vs not enough is *always* the answer when you're a glider.
Air Canada achieved 12:1? I believe they also had tons of energy, which could have been used, in an optimum situation, to achieve a better glide ratio.
And what speed was used in the descent? Makes a big difference in your glide distance. Can be checked by doing the math on TAS/sink rate at various speeds and glide ratio(w/idle power) can be computed.