What would you do?

[Admin]

You have taken off and suddenly the engine fails on your climb out - you are only about 200ft AGL and the only put down place is straight in front of you.

 

It's a field with the longest side being left to right but there are trees in these ares so the only choice you have is to put down in the shortest side and you know you just may or may not make it before you get to the fence.

 

You throw the aircraft into a massive slide slip to lose height so that you will get down just over the first fence - you clear it by 5 to 8ft - the wheels touch and you immediately throw the brakes on hard - the other fence is coming up at you very quickly.

 

You are about 50ft from the fence and realise you are going to hit the fence at about 20kts - what do you do?????? (Note - in your thoughts think of speed as a variable, in other words what if it was 10kts or 15kts or even 25kts - you get the idea)

 

Do you hit the fence straight on hoping that the aircraft will brake the fence wires and slow you down to a stop - but the jolt on your body is going to hurt?

 

Do you suddenly turn the aircraft so the wing hits the ground as you think this will be a better impact on your body?

 

Either way the aircraft is going to be severely damaged so you have to think about the damage to your body like your neck.

 

Is there another alternative?

 

 

[Barefootpilot]

Ground loop the aircraft. Depending on what type of aircraft your in you may get away with not doing any damage at all to the aircraft at up to 25 kts. Worst case you will probably wipe out the gear and touch a wing on the ground but its better than going through a fence and getting thrown on your back.

 

My 2 cents.

 

Adam

 

 

[blueshed]

If it were my BD4 I would take the fence straight option, as I have high wings, if it is an average fence they will be above the fence, as I have a conventional undercarriage (tailwheel) my nose will be high, so it probably won't flip, I will be stopped like in an arrester net at the end of the runnway.

 

However if there seemed to be enough time to make a more gentle turn, meaning before you had slowed to 25 kts you may be able to avoid the fence all together by creating a large arc as you land. Doing this may also use some of the energy in the form of speed reduction as you turn.

 

If you were in a nose wheel aircraft it may all be different!

 

Fly in and Hangar Dinner @ Jamestown SA 19 April 2008, would love to discuss this in person!

 

Cheers Guy

 

 

[Admin]

Remember there are trees on your left and right

 

 

[facthunter]

INTO THE FENCE.

 

If it's a tractor, with good protection around the windscreen, and the brakes are working. I would apply maximum braking and just try to avoid hitting the posts. The wires will be a good method of retardation, as they will have a lot of "give". If you are in an aircraft such as a drifter or a glider, the risk of being decapitated is too high to contemplate going straight at a wire fence, so hit it side on. Turn into wind only available if a crosswind exists. Nev..

 

 

[Guest browng]

Interesting one Ian, and difficult to be sure without a bit more data, eg how much if any runway is ahead of you? what is your best glide speed, what is your MTOW (therefore momentum). If you are only at 200ft there could well be considerable runway ahead of you, particularly in a high climb angle type. The side-slip will, depending on type, add 5-10 knots to the speed, or you risk a stall/spin. We are going to hit a fence, do we get back down on the runway knowing we are going to overshoot and take the first fence?, or do we take the second? If getting over the first fence by slipping means we arrive 10knots faster for the second one, maybe it is better to take the first? As to ground-looping, maybe, but if it is a lightly wing-loaded type, the accelerated velocity of the outer wing in the loop can easily see that one wing flying again, with the resulting risk of the inner wingtip striking the ground and and causing a roll-over, could be nasty if the fuel is in the wings. We don't really have all the details, but on what we do have, I'd probably take the overshoot if available, and the first fence.

 

 

[BigPete]

Turn off the motor (and fuel pump/tap) and hit the wires not the posts. (if possible)

 

regards

 

 

[John Brandon]

I'm currently finishing off the safety feature article for the February and March issues of Recreational Aviation Australia. This article deals with the problems of landing too fast in an emergency.

 

I would be interested to hear from anyone who has put an ultralight, or any light aircraft, through a properly constructed farm fence. As you may know each strand of a four or five strand barbed wire cattle fence is usually strained up to 100 kg and the 2.5 mm mild steel wires each have a breaking strain around 3000 newtons [300 kg force]. The 4 point barb clusters are spaced at 10 cm. From the damage I've seen to a four wheel drive vehicle which was allowed to roll downhill through my boundary fence breaking through the top four wires I conclude the damage to an aircraft and occupants might be horrific. I don't think an ultralight moving at 25 knots would break through such a fence nor would it stretch mild steel barbed wire very far and of course there's always the chance of hitting an intermediate post.

 

When the fence is struck at an angle the barbs act as a very effective chain saw.

 

cheers

 

John

 

 

[Guest browng]

I would be interested to hear from anyone who has put an ultralight, or any light aircraft, through a properly constructed farm fence.

Not personally, but my first piper Cub, G-BPPV, (which after I sold it went to Ireland and became EI-CUB), was but through a stone farm wall with only minor injuries to the 1 of the 2 POB. photo below.

 

 

I also found the following in FS Magazine;

 

3/9/05 Piper PA24-260 Comanche 39 km E Melbourne, Vic. Injuries: Nil Damage: Substantial. The engine failed during the cruise. The pilot landed in a paddock, where the aircraft hit a fence. Inspection revealed a faulty engine fuel control unit.

 

11/9/05 Cessna 172N Skyhawk Bankstown, NSW. Injuries: Nil Damage: Substantial.. At approximately 200 ft AGL, engine RPM dropped significantly and the pilot carried out a forced landing near the airport perimeter. At touchdown, the aircraft collided with the perimeter fence.

 

 

 

And below is a link to the report of an incident in the UK where the aircraft hit a fence hard enough to damage both spars, but the pilot was uninjured.

 

http://www.aaib.gov.uk/cms_resources/Tri%20Kis,%20G-TKIS%208-05.pdf

 

I don't know if any of this is useful though.....

 

 

[Guest High Plains Drifter]

Browng,

 

Mr piper made them tough.

 

The wire fence in the foreground appears intact - did tha A/C come in over it?

 

HPD

 

 

[Guest browng]

Browng, Mr piper made them tough.

 

The wire fence in the foreground appears intact - did tha A/C come in over it?

 

HPD

Yes it did, here is an excerpt from the report,

 

"The pilot stated that after getting airborne the right wing of the aircraft was lifted by a gust of wind. Despite his full control input the aircraft was blown some 90� left of the runway direction and flew about 80 metres over the grass perimeter and impacted the airfield boundary stone wall. The aircraft demolished part of this wall and came to rest inverted in the adjacent ploughed field.

 

 

 

As you say, tough little bugger...........

 

 

[storchy neil]

straight in miss the post neil

 

 

[Whack777]

I'm assuming I'm flying a Jab. My first instict would be to avoid the fence at all cost and ground loop the aircraft. I'd put my left arm over my head to try and cushion side impact.

 

Reason: I'd be worried about any wires slicing through the cabin so choose to ground loop prior to the fence. In a ground loop I assume there would be a tendancy for your head to want to keep going in it's original direction and therefore possibly impact on the side of the cabin (for you or your passenger depending on the direction of your ground loop)....

 

Looking forward to others thoughts/comments.

 

Good question Ian

 

Regards

 

Wayne

 

 

[Guest pelorus32]

Ground loop. I say that for two reasons:

 

1. Firstly I'm not interested in experimenting to answer John's question. I don't want to flip on my back and I don't want to be decapitated by wires;
    
    
   
2. I want a slowish deceleration, it's the speed of deceleration that kills you.
    
   

 

Change your scenario Ian to an irrigation channel rather than a fence - the answer then becomes obvious. If you allow yourself to go into an irrigation channel at 20-25 knots you'll come to a sudden halt when you hit the far side. I'd always ground loop before I got there. The a/c might crumple around me in a ground loop but it would be a slow crumpling - wingtip, wing, undercarriage etc. Hitting a well constructed fence or the far side of an irrigation channel would be a rapid stop. The human body doesn't like rapid stops.

 

Regards

 

Mike

 

 

[Mathew Ker]

Well Mr Instructor (Ian),

 

Great question/scenario. It's been 24hours, there have been 13 suggestions.

 

My question as a student pilot is - What would you do? :)

 

Regards, Mathew

 

(Eagerly waiting for the DS solution!)

 

 

[Admin]

;) - well, first let me say that I am not an instructor but soon will be through the club/school at Wangaratta.

 

You have caught me out - what would I do? hmmm, knowing that my engine had failed so the prop would be stopped (no engine damage through a prop strike) I would go for the fence and at the last minute pull back on the stick as even at 20kts I may get the front wheel off the ground ever so slightly and if not at least the weight would be slightly transferred to the back of the plane so when I hit the wires it may lift me up a little making the jolt not so hard. But, I would also lift my legs up (assuming the aircraft didn't have toe brakes) and assume the crash position with my head forward even though for example my old CT had high back seats with headrests.

 

Well, that's what I THINK??????? I would do

 

 

[Admin]

Interestingly no one has mentioned anything about flaps - would flaps down help or flaps up - flaps increase drag and gives lift - would speed be reduced more on the ground if at full flaps???? would the lift also drain off speed ;)

 

 

[Guest browng]

Interestingly no one has mentioned anything about flaps - would flaps down help or flaps up

Ian you stated that, " You throw the aircraft into a massive slide slip to lose height so that you will get down just over the first fence". In many types, side-slipping with flaps extended can be a very unhealthy pastime. Another comment I would like to make is that you rarely read of fatalities due to hitting something in the horizontal. In engine out fatalities it's usually because they have undershot, pull up to try and extend, and stall/spin, resulting in a vertical impact.

 

 

[Admin]

I agree browng which is why I said "would speed be reduced more on the ground if at full flaps????" :big_grin:

 

 

[Guest browng]

I agree browng which is why I said "would speed be reduced more on the ground if at full flaps????" :big_grin:

ahhh, I see, do you mean would the drag of flaps deployed at touchdown help deceleration? That might be worth doing if the flaps are manual and can be deployed almost instantly, but most electric flaps would take several seconds to deploy, probably not much use?

 

 

[motzartmerv]

What 'types' is slipping with flap out a bad thing..Please dont say jabiru, cause i often do a big slip in these slippery planes..

 

an engine failing at 200 ft..hmmm...By my reckoning by the time you nosed over to maintain the airspeed you'd be well under the 200ft, mabye as low as 100 ft by the time you got the attitude right, which wouldn't leave much time to be pulling massive manouvers...but i would reckon its better to hit a fence after youve landed rather then while carrying flying speed..Like Ian said, i think i would be back hard on the stick right through the touchdown and after, even if (in a tricycle) you are digging the tail into the ground the longer you can keep it at maximum angle of attack ie the biggest drag profile the quicker you should slow down..and getting your head below the dash would be a good thing to..But most important, i would get the fuel and electrics shut down..PRONTO..i hate fir..lol..I have seen spooked cattle go through fences and the higher rungs on a wired fence would tend to be weeker becasue they are further from the ancor point..ie, the ground..but a spooked 500 kilo steer makes short work of them..

 

 

[Guest browng]

What 'types' is slipping with flap out a bad thing...

Look in the Pilot Operating Handbook, (POH), if the POH does not contain a procedure for side-slipping, you shouldn't really side-slip. If it does, it will say whether it can be done with flap or not. Having said that, in the real world not all POH will go there at all, but you can bet that if slipping with flap is unsafe it will be in the POH. Not all types have a powerful enough rudder or elevator to slip safely, even without flap. Bear in mind that you are cross-controlled in the slip, the only ingredient you now need for a spin is a drop in airspeed, your stall speed has just gone up because you are cross controlled, and your ASI will be telling lies. Some types are prohibited from prolonged cross-controlled flight because of the potential for unporting their fuel systems, and side-slips are not recommended for some types with certain flap configurations because of a tendency for elevator oscillation. As an example, the C172 elevator can lose authority in a slip with flaps. Later models are placarded that slips with flaps are not recommended.

 

 

[facthunter]

Flaps on short landing roll?

 

For best braking on the ground (where else?),, More weight on the wheels is the go, so deploy spoilers or flaps up I would say. We're splitting hairs here a little, but assume we are talking principles, for the discussion. Nev ...

 

 

[motzartmerv]

flaps up?...increasing the stall speed, reducing drag, all to get weight on the brakes that don't stop an aeroplane dead anyway??hmmmm...spoilers?? obviously a glider pilot??...lol...

 

Avoiding the stall and spin would be numer one priority...Remember....:

 

"The angle of arrival is directly praportional to the probability of survival"

 

 

[Guest browng]

I'll admit that I'm a bit out of my depth with the physics of braking here, but as I understand it, braking occurs by converting kinetic energy to heat via friction at the disks/drums. How does putting more weight on the wheels make that process more efficient?