Maximum glide

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JPB
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Maximum glide

Post by JPB »

Just wondering...Scenario of engine failure protocol. If you are flying at desired altitude with no apparent problem and your engine(s) quit. Do you drop altitude for more air to attempt a restart or do you first go to maximum glide references first ? I am asking because if you lose altitude for a restart and there is no restart you could be below the max glide reference. Is there an order of actions that are standard ?
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PilotDAR
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Re: Maximum glide

Post by PilotDAR »

The best right answer is to follow the flight manual procedures. If there is no requirement to find a lower altitude for an engine restart, I would set up for a maximum glide right away, unless you observe that you are high for a suitable landing area very close by. Then you must decide if you would like to attempt a restart in flight, or just land.

When I teach forced approaches, I teach them to a landing (not just an overshoot), and I remind the candidate pilot that the speed for "best glide" presented in the flight manual will be the speed which takes you the greatest distance for altitude lost, it might not be the ideal speed for the final segment of your gliding approach, that may be comfortable a little faster. Your first clue to this will be the relationship between "best glide speed" and Vy for your aircraft. The faster of these speeds will be the better speed for the final stage of your approach. You can always slip off a few too many knots if you're too fast, stretching a glide is much less certain. And remember that it takes a little bit of your stored energy (as speed) to flare, so don't arrive to the top of the flare gliding close to your stall speed, as you will just thump in when you pull to flare.
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Chris M
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Re: Maximum glide

Post by Chris M »

Assume it's toast and plan accordingly. You can attempt a restart but priority one is to set yourself up for a survivable landing.

The only exception I can think of it if you were clearly in an environment that could kill your engine - heavy icing, or ash cloud if you're a big plane - where descending out of it dramatically improves your restart chances.
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TT1900
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Re: Maximum glide

Post by TT1900 »

Short answer, it depends.

What type of aircraft, what is standard cruising altitude (are you dealing with pressurization & potentially oxygen problems?), does the engine have a starter of some kind or will you need ram air of a certain speed to restart, do you need max glide or do you have excess altitude to a suitable field?
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Adam Oke
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Re: Maximum glide

Post by Adam Oke »

I'm assuming we're talking generic small pistons. Any engine failure I've had in a piston was catastrophic with the exception of one successful relight. First action for me has always been to establish best glide and find a suitable landing spot before doing anything. Out of my just shy of a handful of engine failures, best glide and picking a suitable spot to land has allowed me to re-use every aircraft with no additional damages. I think I'm almost out of horse shoes mind you.

Something to add, it takes a lot to stop most small piston propellers (slow airspeed to stop it). They tend to windmill pretty good if it isn't feathered. I would think it's pretty uncommon to have to dive to spool it up again. Something to assess if it was a sudden stoppage vs a slow spool down.

Another reason why a gliding license is a great asset. Do some reading on polar curves. Sometimes best glide isn't the best. If you're trying to punch through a headwind, increasing airspeed to a certain extent will be more beneficial if you are trying to cover ground. Much like flying flying min sink with a tailwind will buy you some time and distance.

I also recall early on in my training that roads were being taught as not good options. Every. Single. Engine failure. I have put it on a road. I have operated spray planes off roads and I'm very conscious of hazards at low level (wires among many other things), so I'm confident in my ability to avoid hazards. Do what you feel is safest, but I still recommend roads over anything other than an airfield for anyone that asks for my opinion. Obviously use your head...the 401/427 in rush hour over Toronto would be the last place I put one down. Don't choose a portion of road in a subdivision or near farm houses.

I will also note, that not one engine failure of mine in small singles went textbook. None had radio calls, some I didn't have time to cause check. One I didn't even feather. Most of mine have been low level. I think with these numerous personal real life examples; finding a suitable landing area is your number one concern. If you can do that, a successful outcome is increased substantially. After all....it's just a shitty glider at that point, and hundreds of KIDS learn to fly gliders every year in Canada. ;)
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youhavecontrol
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Re: Maximum glide

Post by youhavecontrol »

If it's not immediately obvious why it failed, I'd first trim for best glide while choosing somewhere to land. Once your field and glide approach are established, you can figure out what went wrong and make necessary changes. There's no reason have a prop windmilling in the hopes of a re-start if you only notice later that your fuel gauge says zero... and you still haven't chosen where to land yet.
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