Noe wrote:
Then once landing spot decided on, best glide.
Well, yes but….
Try a power off approach at this speed, followed through to a power off landing. You may find that once you have the spot made, you’d like to carry an extra 10 knots into the flare, to allow you time to flare. The “best glide” speed is a certification requirement for maximum distance per altitude lost. Yes, you can flare and land from this speed, but great skill and precision must be applied – flare too high, and you’re dropping on. If you have arrived to the flare at best glide speed, and are too slow/low, you’re stuck, and headed into the hedge. If I have to get it wrong, I would rather be wrong too fast than too slow, as I would rather go off the far end of my spot at 10 knots unable to stop, than slam into the near hedge at 50 knots, unable to squeak over it.
I am a strong advocate for forced landing practice to a full stop landing, to practice the entire event. The go around at 200 feet ’cause you had the spot made, is woefully inadequate. Forced landings are a perishable skill, and should be practiced regularly.
On a slight tangent, would one not go to full flap at the last moment, to convert some kinetic energy into height?
Obviously this won’t work on a type on which the full flap is mostly just drag – e.g. the C150/152 from vague memory.
While the increase in camber increases the coefficient of lift for a given AofA, it will worsen the L/D ratio. Your aiming point on a forced landing is the middle of the field for an aircraft with flaps, by adding full flaps the aiming point will move towards the beginning of the field, and yes full flaps leading to reduced Vat reduces kinetic energy. In a typical training type the L/D is around 10:1 clean, and around 4:1 with full flaps.
More modern types are more efficient, a DA-20 might be 13:1 clean? The SET class (ex Caravan or PC6) comes in at 15:1.
If the circuit is empty why not carry out a constant aspect practice forced landing every time you return to base? Some folk, usually if they have been MEP instructors, have faith in the intrinsic safety advantage of the single engine, but only if you work at being current on your PFL skills.
Pilot_DAR wrote:
Try a power off approach at this speed, followed through to a power off landing. You may find that once you have the spot made, you’d like to carry an extra 10 knots into the flare, to allow you time to flare.
On the aircraft I fly, the best glide speed is well above the recommended threshold crossing speed and I usually reduce power to idle when crossing the threshold. I don’t have any problems with the flare. Indeed, when I practise power-off landings, I still aim for the proper threshold crossing speed and the flares work just fine.
It could be more of a problem if the aircraft has higher wing loadings, but even the TB20, which has quite high wing loading, has a best glide about 20 kt above threshold speed.
(I certainly agree that it is better to come in high and fast and risk overrunning the runway than low and slow and risk undershooting, but that’s a different issue.)
