A very bad day - unless?

[slim_slag]

Indeed Cosmos.

OK, for the rest of you, if you don't feel competent enough to do a Vne dive then dive at Vno.

There isn't a decent answer to this question, you are up the creek without a paddle, if it's cloud all the way to the ground you are screwed. If there isn't cloud all the way down you want as much time as possible when you break out. Would you all agree on that?

[Genghis the Engineer]

Q for GtE: Why landing flaps? My thought would want to reduce the possibility of sink, even if I am 5-10kts faster. Maybe one stage of flap?

Two reasons, firstly if the engine has stopped and I am going to hit the ground anyhow it makes little difference to me whether that's in 4 minutes or six. Secondly, land flaps will make the descent angle steeper (thus reducing the risk of hitting a mast) and stall speed as low as it'll go, so my energy when I do finally hit something is as low as possible.

OK, for the rest of you, if you don't feel competent enough to do a Vne dive then dive at Vno.

Again, I'm descending anyhow, why risk loss of control by doing it in anything other than a sensible low speed / lowish sink descent. If I come out of cloud at Vs+5 at 100ft, or at Vno at 100ft, my odds of controlling the ground impact in a reasonably horizontal manner are far better at low speed. This is for the very simple reason that a significant amount of height is lost in changing from a fast dive to horizontal flight.

If I know that I'm going to come out at a reasonable height above the surface, I'd use min.sink, but if I don't, I'll stick with Vs+a_little_bit since that's the best thing to hit the ground at.

G

[Timothy]

Thank you all for reminding me why I send the children up chimneys and the wife on the streets so that I can afford to operate a twin.

[yawningdog]

I agree with Slow-Rider on this except for one thing,

- Select the book glide speed for forced landing.

- Do not attempt any turns in IMC. Too risky, no available power to fix any errors.

- Do not select gear down or any flap until you actualy see a landing zone.

The extra drag from gear down is huge. Landing wheels-up shouldn't cause any extra risk.

[bookworm]

Thank you all for reminding me why I send the children up chimneys and the wife on the streets so that I can afford to operate a twin.

Oh that's how its done! And here was I thinking that it was more efficient to make them pedal...

[Miserlou]

A word of warning about this 'expect the cloud base is...' business. Psychologically your building in a potential overload, ie. when you get to 800 feet and you haven't broken out yet and you don't have a plan for the last bit. Stress, stress, stress!

Also I would suggest that, bearing in mind that you may not be as current on partial panel as you should be, one would perhaps be best served by keeping the workload as load as possible. That it to say continue with the trimmed speed until you are stable in the glide then perhaps slow down gently to min sink and head into wind.

Those two items will put you in the most survivable situation you can hope for in your current circumstances.

[Andy_R]

Thank you all for reminding me why I send the children up chimneys and the wife on the streets so that I can afford to operate a twin.

Nice one

A word of warning about this 'expect the cloud base is...' business. Psychologically your building in a potential overload, ie. when you get to 800 feet and you haven't broken out yet and you don't have a plan for the last bit. Stress, stress, stress!

Having been there (albeit with an engine) I can vouch for that. Nothing is worse than expecting to break out of cloud and then......... not. The stress levels rise incredibly and can only affect your performance adversely.


Reckon I would go with the Vs +5 option. At least if you do hit something you will have reduced the amount of energy available to cause you damage.

[High Wing Drifter]

Two reasons, firstly if the engine has stopped and I am going to hit the ground anyhow it makes little difference to me whether that's in 4 minutes or six. Secondly, land flaps will make the descent angle steeper (thus reducing the risk of hitting a mast) and stall speed as low as it'll go, so my energy when I do finally hit something is as low as possible.

Thanks for taking the time to explain. I think I understand the effect of flaps. But you mentioned turning and I assumed that you would wish to stay airborn for as long as possible or until you decide its time to descend. My understanding and limited experience is that although landing flaps (i.e. much drag) would reduce your landing speed, they would also reduce the controlability of the aircraft. I think I would always maintain a configuration that would allow me to extend the glide for as long as possible until the point where I think I have a chance. Adding flap (esp with a PA28) is usually easy. Taking it off is invariably won't be. Maybe electric flaps pose problems with this particular scenario.

[Thumpango]

Umm.. think I will stick with VFR and keep well away from cloud.

this IMC lark sounds far too risky!

[GusHoneybun]

One for the engineers amongst the assembled masses.

Exactly how quickly would the AI and DI start to wind down to give spurious information? Also, as the vacuum pump is linked to the engine, and your prop is windmilling then would this still be driving the pump? and would there enough suction to provide a 'useful' AI and DI.
Just wondering because the initial reaction to anything this serious would be to believe your instruments, which could present even more problems when you do break cloud inverted! Vne or not, not much time to get sunny side up.

Tis a silly thing to do anyway.....

[yawningdog]

I would suggest, if the engine quits, then don't believe anything that requires the engine to be running. That simple. So transfer over to limited panel ASAP, & cover up the AI & DI if poss.