Gear fails - Put down on grass or tar?

[silverknapper]

If the gear were to fail, and I mean it stays retracted as opposed to unsafe warning, what surface is best to put down on?
I used to think grass without a doubt, and it was a stupid question. But someone has just told me that tarmac is the lesser of two evils and does less damage to the aircraft.
Am I being wound up? Anyone got any thoughts?

Cheers

SK

[Genghis the Engineer]

I'd certainly say grass - to hell with damage to the aircraft, that's what insurance is for.

On grass you can expect less sparks, reduced impact peak loads, and better braking, three things I'd enjoy enormously under the circumstances.

G

[bar shaker]

Sparks won't be an issue unless fuel is pouring out of the wings.

Impact loads will be much less on a flat tarmac runway. Grass strips are not flat. With the belly of the aircraft sliding along the surface, the bumps of a grass field at 70kts are far more likely to break up the aircraft and the occupants.

I'll accept that there's less breaking on tarmac (than dry grass), but then tarmc runways tend to be quite long.

Given the choice of a gear up landing at Headcorn or Biggin, I know which I would choose.

[2Donkeys]

Every authority I have ever heard on this subject recommends a hard surface (concrete or tarmac). The unevenness of grass and the high likelihood of part of the airframe digging in and causing a flip, twist or breakup is the usual reason cited.

2D

[Quickloop]

The only GA event I can recall, the pilot elected a foam carpet, that must be at least 25 years ago. I know the plane is still flying, and the pilot alive.

[Genghis the Engineer]

Looks like I'm outvoted!

G

[benhurr]

Reading the question.... I go with Genghis. but we are still outvoted - given the choice I would go with a fairly tall standing crop - broad bean:)

[Secret Squire]

from my very limited experience - I'd be inclined to go for a hard surface, for the lower probability of digging in and flipping... along with bailing out rather than ditching for same reasons (yes I do fly with a chute most of the time!)

[ChrisVJ]

Our group has several experiences of wheels up on grass. Since we fly amphibs and the prop is behind the wing and above the hull we present a smooth surface. Ususally there is no damage, Just jack her up, drop the wheels and motor away.

The braking effect of grass is pretty good, far more so than regular brakes. When I was watching a wheels up the plane stopped in about 30 to 40 yards.

A few weeks ago one of our group put his plane down wheels up on tarmac. He realised as he 'sank' just what he had done and elected to power up. Took him about 2oo feet to get enough flying speed to drag her off and left a whacking great scar down the bottom of his fibreglass hull . Somewhat surprising that he got enough speed and elevator authority to get the nose up enough to lift off.

(By the way, Wheels down on water wrecks it every single time.)

Of course if you are wheels up in a regular plane walking away is the point, personally I don't have a clue but emotionally I'd choose the grass.

Are there any statistics on this?

[IO540]

I would fly to a place with a hard runway, avoiding one with a dodgy maintenance firm nearby (just in case the insurance company decided to get it fixed by them) :O

[2Donkeys]

The issues associated with landing a floatplane are totally different to those associated with one which is not ordinarily designed to land without its wheels.

The kind of aircraft that most people fly here may well land with some wheels extended and a propeller or two, all of which will jab into the ground on landing giving rise to the risk of a violent decelleration and/or a flip.

Landing a pair of floats or a hull on grass is not really a fair comparison.

2D

[Droopystop]

Saw a twin do it at Elstree (onto tarmac) a few years ago and there was very little damage done. Horrible noise though.

Just out of interest, the actions for a uncertain gear position on a S61 is to put light contact on the wheels, and get someone to insert the safety pins into the undercarriage. Down and bolted. Seen it done too. The advantages of stopping then landing.

[Maude Charlee]

Fly to the nearest turf grower's fields and get the best of both worlds - the smooth prepared surface of tarmac, and the braking and fire retardent properties of grass. Then run like hell!

[AerBabe]

John Farley wrote a fairly in depth article on the subject in Flyer mag a while back. Perhaps someone can remember which issue? He also went into what your best options were if the gear on only one side were to fail.

[ShyTorque]

Friend of mine once put down a Buccaneer, with total hydraulics failure, on the runway at St Mawgan.

No flaps, no gear, no airbrakes. Threshold speed of about 200 kts. The drop tanks, which were thought to be empty and kept on board to prevent the aircraft flipping over, wore through on the tarmac and the leaking fuel from them caused two major fireballs, the first way behind the aircraft, the second briefly engulfed it.

An (impressive) video was taken of the event. As the Bucc came to rest, the canopy opened within a second. Two crew jumped out and exited the camera frame, stage left, running like hell. Quite a while afterwards, the fire engines, which had been on the threshold and had to give chase up the runway, appeared wide stage right.

Don't think he would have done so well on the grass.......

[TD&H]

Have done one so will throw in some thoughts. But what works for one incident may not work for another. Therefore think and plan.

Low wing aeroplane, decided to land on tarmac. The nose gear was half up/down and floating, decision made to land with mains up. The landing run was short, but deceleration not uncomfortable, flaps helped keep wings level.

Lower cowling, prop (not quite stationary), flaps and some lower fuselage skin damaged. No damage or stress to the two of us though, much to the disappointment of the local TV team!

Most importantly, take lots of time to think about where you're doing it, what RFF facilities they have, make sure ATC are fully aware of all circumstances, don't let them put you on an 'out of service' runway to limit their disruption, take the most into wind and benign runway/approach you can find. Plan your actions, eg who opens doors/canopies, who exits which side, who turns off fuel, electrics etc. Do your straps up TIGHT, think of where loose objects will end up, etc. Relax, carry out your plan.

Go for a beer afterwards. Most definitely do not accept any other form of counselling, because it's not needed/ will only make things worse!:)

[englishal]

Hard gets my vote....

[silverknapper]

This has turned into a most informative thread - many thanks for the replies.
TD&H - Many thanks for reliving that one. I presume you were in a single(you mentioned prop in the singular)? Were it a twin would you still have elected for mains up?
It's something which to be honest I hadn't thought much about before. I just thought grass - soft - thats the one.

[MLS-12D]

Happily, I have no personal experience of this issue. However, I have read various texts, safety bulletins, etc. suggesting that for most light aircraft, the question of grass vs. pavement is essentially academic: provided that the pilot keeps his cool and doesn't stall in or land extraordinarily 'hot', a 'gear-up' landing is almost always survivable, and usually results in modest or even minimal damage. I have several friends who have inadvertantly landed 'gear-up' on grass, and their experience bears this out.

The issues associated with landing a floatplane are totally different to those associated with one which is not ordinarily designed to land without its wheelsI don't have extensive experience flying over water in a landplane, or flying over land in a seaplane. However, I do know that I have always felt much, much more comfortable in the latter situation. Properly handled, a floatplane can make an emergency landing almost anywhere (including many places a landplane couldn't handle), often with little or no damage to the floats. Again, I speak without personal experience (touch wood!), but this has been demonstrated many times and is supported by many authorities (Faure, Frey, Kurt, etc.).

[Gertrude the Wombat]

Properly handled, a floatplane can make an emergency landing almost anywhere
Did some floatplane training on Vancouver Island a year or two ago. Got quite used to the Canadian version of Rule 5 - "so long as your floats aren't actually touching the treetops you're high enough".

Got used to flying around 100' above water - engine fails, just land. Found it more difficult to get used to flying around 100' above land - what do you do if the fan stops?

Instructor said, pointing at dirt track: "oh, we'd just put it down on that forest road, shouldn't do any real damage to the floats".

[Say again s l o w l y]

Fortunately I have no experience of having to land with no gear, but I've seen the aftermath of a few on both tarmac and grass.

The first was on grass and was inadvertant (A v.senior training captain who said he was used to having an F/O remind him!) Luckily the grass was very smooth and the touch-down gentle. The damage was limited to the prop and the flaps.

The second was on tarmac and was intentional (I can't remeber the exact reason why). The touch down was again pretty smooth but the damage done was a lot greater.

At the end of the day I would always choose tarmac with a foam blanket or water sprayed on simply because of the guaranteed smooth surface which I feel is the most important factor.

Damage to the a/c is of very little importance as long as you get out ok, though if you do less damage to the machine, there is less force to be transmitted through to us.

Though if I had a choice between a smooth grass surface and tarmac I'd go for which ever had the better emergency cover and more importantly, which place had the best bar 'cos let's face it, you'll need a drink afterwards!

[Quickloop]

Forgot the punchline to my post...............


--------------------------------------------------------------------------------

"The only GA event I can recall, the pilot elected a foam carpet, that must be at least 25 years ago. I know the plane is still flying, and the pilot alive."

---------------------------------------------------------------------------------

The pilot missed the foam!

[niknak]

Consider this.....

The first thing we would ask you is,

1) do you have any other form of emergency which requires you to land ASAP?

and

2) What is your fuel endurance?

If your answer is to

1) No.

and / or

2) 1 hour +....

You can naff off somewhere else, we don't wnat you blocking our runway and creeating the subsequent loss of revenue.

This may sound very callous, but sadly, it's something you'll be asked about at most commercial / licensed airfields.

[Say again s l o w l y]

To which my reply would be tough!! I'll make the decision about where I as the aircraft captain want to put it down not anybody else and I certainly won't be swayed by 'commercial' decisions.

Niknak, I do hope you are jesting? If someone even suggested that to me in this situation, there may well be a 'quiet' chat behind the bike sheds later on. I would expect better from our colleagues in air traffic.

[TD&H]

Say again Slowly:

I very much agree with your comment, should we both take niknak behind the bike sheds for a chat?!

Go somewhere appropriate, at one time that could mean no end of military airfields where you could feel confident of a good service and a good beer afterwards.

Silverknapper, yes 'twas a single, would have done the same in a twin. However the important thing is to decide what and where are your best options at the time, what sort of gear, how it retracts (if it's partially up/down). High wing with narrow round fuselage, then it will more than likely roll onto a wing tip at some point.

Most importantly fly the aeroplane all the way, don't give up six feet above the ground. Then enjoy the beer afterwards.

[Circuit Basher]

Until around a year ago, I was in regular contact with someone who worked airside at EDI, responsible for operations.

His words to me may be paraphrased as 'We always keep a JCB on standby, for the event that a GA aircraft blocks our main runway. The cost of replacing a light single is cheaper than any penalties we have to pay for delay to commercial scheduled flights'.

Basically, the attitude was that any emergency for resulting in a blocked runway for which clearance would impede scheduled operations - bye bye GA aircraft! I didn't enter into the argument about preservation of evidence for AAIB, etc as the guy had a total down on GA ops at EDI!

[MLS-12D]

SOS/TD&H:

I agree fully that the pilot-in-command is the only person authorized to decide how critical an emergency is. Once an emergency has been declared, ATC has a moral and legal duty to render all possible assistance, not to be ostructionist.

Remember the old chesnut: "What is the similarity between air traffic controllers and pilots? If a pilot screws up, the pilot dies. If ATC screws up, the pilot dies."

"Controllers" don't control anything, except a radio microphone.

But let's not be too hard on old niknak: the last sentence of his post suggests that he is just reporting what most (all?) controllers would do, not attempting to justify it.

[Send Clowns]

niknak

Well another score for Bournemouth International then - no such issues here.

Have seen a few land with uncertain gear condition, had one myself (on CPL skills test! No extension on PFL, got 3 greens in the end). ATC are always helpful to emergency aircraft with inspections, lots of reassuring chat, calling operator if advice needed, and allowing the pilot to choose when to approach. Also helpful to other aircraft training in the area, warning them and letting them land first if the emergency PIC doesn't mind, just in case he fouls the runway (important for mine - the other aircraft was a Vampire, not overladen with fuel!).

Only seen one "expected" gear-up, he had one main unlocked which collapsed. A couple of accidental. All cleared up in under an hour.

Is Bournemouth the most GA-friendly International Airport around? Bigger than Southampton and twice as cheerful :p

[Onan the Clumsy]

The damage was limited to the prop My understanding is any time there is a (significant) prop strike, the engine gets a tear down :( as there could be significant, unseen internal damage, most importantly to the crank. :{

As for a gear up landing, I have heard tarmac is to be preferred as (1) the damage done isn't that great and (2) it's smooth. Grass may look softer (not necessarily so in Texas though :ouch: ) but if you're skidding along at sixty mph and you hit a little indentation, or a clump of something, It could get nasty fairly quickly.

Then there's the airframe shape to consider. It's not likely you'll be flying an F16, but consider the ram ifications of landing that on the grass, with the air intake being where it is.

As for one MLG only, I'd definately take the tarmac, no questions. I wouldn't want the wing tip to dig in on grass and start a cartwheel.

Love the story about the belly up seaplane landing and subsequent go-around. I've heard of people doing that in land planes too :ooh: which sort of brings me back to the start of this post.

[Say again s l o w l y]

In the case I mentioned, there was definately a 'teardown' to see if the engine had been shock loaded, but he'd got away with it!!

[Flyer Flier]

:D Does this one count?

http://www.airclark.plus.com/C337.JPG
Pic shows two very relieved companions after the landing. Plus member of firecrew disconnecting the battery for safety.

I chose the grass next to the tarmac and found that the aircraft came to a stop very quickly in only a few yards. I would not have liked to have been skidding down the tarmac runway and developed a sideways motion. I did get the airport staff to check out the condition of our chosen landing area which seemed very good. Also shut down both engines.
Having not blocked the runway, the hard part was now removing the aircraft without damaging it. This we did by placing a skid beneath it (metal sheet) and dragging it away to the hangar, much preferable to a JCB to clear runway!
ATC were very helpful during planning, no hint of being sent away! AAIB were most amused when I phoned to report the event, as they already knew everything. It was very rare they said that they are phoned two hours prior to an accident by ATC to inform them that one was going to occur! Well,.. other than all my normal flights :hmm:
So grass or tarmac ? I still do not know which way I will go next time. Best to fit your plan to the circumstances each time.
Cheers
FF

[niknak]

Well, having posted in a somewhat cack handed manner, I have been taken behind the bike sheds and spoken to...

Seriously though, it is a question you may be asked, and many "airport authorities" (which is not ATC), and these airport authorities now have specific orders for specific situations such as the one here.

We often "standby" for the military, just in case the aircraft can't get into their own nearby bases, however, its very unlikely that we would accept a diversion for a military aircraft who had u/c problems, no other emergency, and sufficiant fuel to make it to their own base or a nearby one.

That mindset applies to many airport authorities when it comes to civilian aircraft, regardless of the size, due to the potential damage that could be caused.

Although, if you declared a Pan with u/c problems, I wouldn't think twice about doing whatever I could to help you, and to hell with the airport authorities opinion....

[Say again s l o w l y]

Don't worry, we knew you didn't mean it!

I am however very surprised that anybody involved with aviation would put profit and hassle above safety.

If I was asked whether I would go elsewhere, unless the alternate had far better facilities (and a better, cheaper pub) then I would be pretty annoyed once I was on the ground, whilst that wouldn't be directed at the controller (I would bet that not one ATC'er would dream of sending a damaged aircraft away to somewhere with lesser facilities) they should really tell the 'airport authorities' to stick it where the sun don't shine as you say.

It is all a bit academic though, it's not as if even the most idiotic 'airport authority' could stop you landing somewhere once you've declared an emergency. They've simply got to deal with it and the conseqeunces.
It may cause headaches, but in that situation, it's not something I'm really going to give a fig about.

Flyer flier, it looks as if you got away lightly with your 'moment', nicely done.

[scrubed]

"land planes" :rolleyes: :rolleyes: :rolleyes:

[Paul_Sengupta]

http://www.avweb.com/news/columns/182676-1.html

See "Select The Surface"

"There are some very interesting films made by NASA when it did full-scale crash tests of general aviation airplanes. The gantry arrangement that had been used for training Apollo astronauts for working under reduced G levels was modified to impact airplanes into the ground at specific angles and speeds. The initial tests crashed the aircraft on concrete. The data obtained showed that some impressively high-speed impacts were potentially survivable. At flatter angles the airplane would hit and then slide along the concrete. For a while though, everyone missed the obvious: The concrete simply redirected much of the energy of the crash. While it stopped movement downward, providing a significant deceleration in that direction, it did not absorb all of the energy of the moving airplane. The remaining energy was translated into a long slide. An engineer visiting from one of the manufacturers politely mentioned to the NASA scientists that, in his experience, not too many airplanes crashed on concrete. The light bulb lit and dirt was brought in and layered about three feet deep atop the concrete.

The same crash tests were rerun. The results were dramatically different. None of the impacts was survivable. The dirt compacted about six inches, and then stopped the airplanes cold."

[LowNSlow]

Did they compact the dirt first? This would surely have made a very big difference.

[Genghis the Engineer]

And that result is not, presumably, representative of mature grass either.

G

[LowNSlow]

If it was representative of a firm soil surface topped by mature grass then Flyer Flier's C-337 would be a bit more bent as would FF and his fellow aviator.

[India Four Two]

Got quite used to the Canadian version of Rule 5 - "so long as your floats aren't actually touching the treetops you're high enough".

I did my float training in BC, so I know exactly what Gertrude means, but for the benefit of anyone who might be inclined to take her comment literally, our "Rule 5" (CAR 602.14 (http://www.tc.gc.ca/CivilAviation/Regserv/Affairs/cars/PART6/602_14)) is the same as the UK rule:

....at a distance less than 500 feet from any person, vessel, vehicle or structure

So you have to hope there are no anti-aviation types hiding in the trackless forests. :)

At least over water you can see where the "persons" and "vessels" are, and in my experience, you get a friendly wave - at least they looked friendly to me!



I cannot get the link to work properly - try this instead - http://www.tc.gc.ca/CivilAviation/Regserv/Affairs/cars/Part6/Subpart2.htm and click 602.14

[Fox Alpha]

"land planes".

What's wrong with that?

[Gertrude the Wombat]

At least over water you can see where the "persons" and "vessels" are, and in my experience, you get a friendly wave - at least they looked friendly to me! Persons and vessels, sure, but I was told that the whales were another problem - the requirement not to land within half a mile of a whale is all very well, but they quickly come along to play round your aircraft so how can you then prove that you didn't land too near to them?

[Yorks.ppl]

I wouldn't choose to land any where near
Wales.



















Sorry. Only kidding Wales :ok: