Emergency landing
 

If in an emergency close to a airfield one is forced to land what is better, the main runway or the foward speed landing area which is grassy but plain surface.

Which one to choose if adequate length is avaliable on both surfaces???

If you can reach either - always the airport.

Why? Fireservice available:ok:

what i ment was if iam at the airport.

emergency on board and want to carry out a foward speed landing with an aircraft fitted with skids.

what to do go for runway or grassy patch next to it.

both of the same length and clear of obstructions

You slide better on tar/concrete

Yes ... but, some runways are grooved (grooves run across the width of the runway) for water dispersion and improved braking for wheeled aircraft. This can be hazardous to skid equipped helicopters especially if one gets a little or a lot sideways. Assuming no acute urgency, I'd probably prefer a smooth (ungrooved) taxiway everything else being equal.

I would have thought taxiway lighting to be more of an issue than runway grooves and bearing in mind the width differences, surely a runway would be a better choice than a taxiway. Having run 'there and back' along the runway of an international airport during the volcanic ash episode, I would conclude that one must have extremely thin skids for any runway grooving to be considered hazardous. :rolleyes:

I've seen slab joints I swear a whole Robinson could fall into, but still preferable to a bumpy grass field.

Grass is quieter. :ok:

If you land on the grass, you won't have a bunch of jets making expensive diversions because the runway is covered in disabled helicopter.

Danger of digging in a skid on grass, go for tarmac.

Whilst the OP later explains he is referring to a skid helicopter, there are multiple scenarios which could dictate either option.

A skid machine generally has plates under the skid to allow for running along a sealed surface, which can (& does!) leave significant surface damage to a runway seal. Does the emergency landing warrant this?

How large is the helicopter, what is the emergency, how far is it likely to slide? Shortest run-on is likely to be a limited power approach, eg single engine failure on a multi. Longest; maybe a tail rotor failure of some sort. For a short run on then take a firm and level grass and leave the runway clear. Longer run for a T/R failure make a judgement call, but I'd lean toward a runway as a more forgiving surface to an off-centre touchdown.

Then there are the wheeled machines and their foibles, most of which would dictate a better sealed surface.

But as already mentioned, that seal doesn't have to be a runway. It could just as easily be a taxiway or even a clear parking area, especially if there is a significant crosswind on the only available runway. The same holds true of a skid run-on landing on grass, lessening the crosswind issues of going for a seal.

Since the OP is from India there could be further considerations dictated by local norms and requirements?!

Edit to add: never, ever, let the considerations of other operations influence a safety call in an emergency. It should be of no consideration that other serviceable aircraft may need to divert when assessing the safest way of getting yourself and your crew or passengers away from the landed aircraft in one piece.

I'd always go for the hard surface. No surprises there. The hell with airplanes and their expensive diversions.

At least with the hard surface you have less chance of a skid digging in, or the cab bouncing fore & aft possibly causing the trailing blade to contact the tailboom

In North America it is routine to do emergency landings on the hard standing, even for practice. Too many potential gopher/rabbit holes in grass. Just be careful about how quickly you put the collective down for the braking action :)

Phil

In France...Inverse, most of the time, we landing on the grass: is smoothly and so quiet...
I make my first full R44 autorotation in Torrance on the runway. The concrete runway is so noisy.....;)

Each way bet, one skid on the tarmac and one on the field.

This is all about risk management
 

ALWAYS choose the hard surface.

Skids: Get sideways in the grass you and might tip over.

Wheels: Same idea.

Wheels on pavement: Nose dragger it will kick straight. Tail dragger you can pedal it straight.

Important thing is, tipping over is much less likely to happen on a hard surface.

And don't worry about grinding the skids (or wheels) - we can always buy new ones :}

What John said
 

Edit to add: never, ever, let the considerations of other operations influence a safety call in an emergency. It should be of no consideration that other serviceable aircraft may need to divert when assessing the safest way of getting yourself and your crew or passengers away from the landed aircraft in one piece.

I guess regional outlooks may have overlooked that in many places, eg Australia, the grass usually is a hard surface!

Amazing how different countries do the same thing in different ways or have misunderstandings about the "other" way.

In my 4000 odd (european) civ and mil rotary hrs I have never once done a run on landing of any kind on a hard surface on skids, nor heard of anyone that did by choice except in the case of some (but by no means all) tail rotor failures as described by John Eacott. On wheeled aircraft we used the tarmac of course. Can't really imagine why you'd want to wear your skid plates away on a runway or mix it in the circuit with the siezed-wings when you have smooth, slippery grass all to yourself.

Never had any concern about "tipping over" on grass nor felt it likely to happen, largely because it isn't, as millions of European training hours have proved.

Only ever done them onto the grass area at the airfield where I am based. Fastest to date is 50knt (training, tail drive failure).


It occurs to me that there is a big difference between an airfield you know - a surface that you know - and the unknown. I would be more likely to opt for the tarmac / concrete if I did not know for sure that the grass surface was suitable & safe.

Starter for Ten!
 

Ignoring of course the times when it has happened :ooh:
(and the many others outside Europe!)


https://assets.digital.cabinet-offic...CCJE_07-06.pdf


… on the other hand;

AOPA Hover Power » Blog Archive » Running landings



Of course grass can always catch you on take off :eek:

I think its going to depend a great deal on the specifics of a particular situation. Grooved runways are typically found at airports designed to accommodate larger aircraft, with taxiways sized (wider) accordingly. Taxiway lights are often mounted somewhat off the paved surface and with frangible couplings which allow them to easily fold over when struck. If the helicopter is sufficiently out of control to leave the pavement (taxiway or runway) it seems likely that the pilot will be dealing with greater problems than striking an edge light fixture. And, taxiways do not have threshold lights, REIL's, approach lights, touchdown zone lights, centerline lights, localizer antennas, etc, all of which could create challenges under some circumstances.

On a related topic, my favorite instructor is a very high time helicopter pilot with a perfect safety record; what little hair he has left is grey. He considers running landings (in skid equipped helicopters) to be emergency maneuvers whether on pavement or grass, and he will teach them only in a simulated form (low approach at an appropriate speed without skids touching pavement). His view is that too many helos have been rolled into a ball training this maneuver. I am 150% sure that this view will be contested here!

Hard surface for all EPs with skids, let skids work (flex) and slide without tripping. Why the concern over fixed wing traffic inconvenience in an emergency?

Taxiway edge lights may well be off the paved surface, (remembering that they are only required at larger airfields if a taxiway doesn't correspond with the paved surface), but even so, I don't think these edge lights are that helicopter friendly in the 'frangible' department. If edge lighting is used, taxiway centre line lights are still required.

https://upload.wikimedia.org/wikiped...iway-light.jpg

http://www.adb-air.com/media/103/2050_ETES-L_004.jpg

For training purpose I prefer grass for the very same reasons as mentioned before ( less wear on the skids, less noisy etc).If the grass runway is all muddy (e.g. in winter time) or if there are too many molehills than you better do something else that day.
A prepared grass runway should be as solid and as plain as the paved runway with its expansion gaps. Same applies to the shoulder next to the runway.
However you might want to check whether you are allowed to land next to the runway (for training purpose). In some countries you are not allowed to land next to the runway (might be considered off-airport landing) unless it is an emergency.
In real life I would probably aim for the concrete.

Funny CRM story at the end: spent my vacation in the US and thought it might be a good idea to refresh my FAA license and get my biennial done.
During autorotation I was aiming for the grass whereas my very experienced USCG FI got an increase in heart rate and, by softly pushing the stick with his knee to the opposite side, tried to tell me to go for the concrete. We put the a/c down safely on the grass which made him somehow breathe a sigh of relief.
However he asked me to do the next one to the paved runway.:):)

The short taxiway light in your photos does not appear to be of the frangible type. The tall taxiway light has what appears to be a frangible coupling at the base of the post. Hard to tell for sure from the photo.

As stated previously, best choice for landing (if there is indeed a real choice) will depend on circumstances. No single choice will work for every situation.

In case of real emergency - choose an airfield with tarmac- and emergency services!!!!

Remeber a training flight, where I was a passenger (my company check already finished), when the student, lowering the collective on a single engine landing, dug in so deep, that the bouldersteps on the struts moved so far up, that student and instructor couldn´t open the doors to get out.
I could get out the back and after unsrewing the bouldersteps, both could get out.
Or remember the MD crash of the policehelicopter at Hannover, where they had a NOTAR-problem.
All went well, until the helicopter veered to the side of the runway and touched grass.....

So in case the sh.. hits the fan - big airfield!!!!

My 2 penn'orth:

Middle Eastern state-owned helicopter, skid-equipped, MAUM 2835kg, airport rules only allow approaches/departures to/from prepared surfaces. Quite right under the circumstances - the off-taxiway areas were proper hard-rock desert, and the dust generated on graded surfaces was very damaging to our engines.

Occasion 1 - Precautionary shut-down of no2 engine, night ops, still air, OAT 41 deg Celsius with runway <100ft AMSL. The options are runway (this particular airport has 2), taxiway or apron. Lighting on runway and taxiway are both edge and centreline with poor visual definition in between. Apron is very brightly floodlit, 600m plus clear area. I opted to go for the apron, which the fire crews ensured were clear of people and obstructions. Touched down at the max-allowed (for that type, in those days) 30kts and came to a stop in just under 100m. Very noisy, and the cockpit was very brightly illuminated by the shower of sparks which we were told extended to 3 aircraft lengths and double our height. Skid shoes replaced, suspect engine checked/ repaired and all was well.

Occasion 2 - running landing training, simulated single engine, daytime, OAT around 35 deg Celsius and wind 10 knots or so from 12 o'clock. Student touched down at <30 knots on runway, halfway between edge and centreline as briefed. After gently lowering the lever because it was clear that we weren't decelerating much, I didn't do enough to stop the student drifting toward the centreline. At <10 knots (estimated) we both felt a slight - and I do mean slight - bump before the aircraft came to a halt having travelled some 200m along the runway. Leaving the student at the controls, I climbed out to check the skids - right rear skid post cracked. Embarrassing runway closure for nearly 20 minutes while the heli was recovered. The skid shoe had hit one of the chamfered centreline light housings; even though the latter was only about 2 cm tall, and sloped on all sides, that was enough to break the skid post.

Lessons learned:

If it's a real emergency, go for a hard surface for all the reasons mentioned above. Be prepared - warn the pax and crew - for the very loud noise.

If you want to shorten the run-on, consider a taxiway or apron/ ORP. They have lower construction standards than the main runway, so their friction is greater. I was amazed how much the aircraft slid along the runway surface even with the lever mostly down.

If you're going to do it at night, be prepared for some very bright extra light in addition to the noise.

There is footage somewhere of a BBC programme covering an event with a very sparky run on by a Lynx. It's out there somewhere ... in the meantime;

Good old Sid.

Never one even to accept the universally established norm that affects his side of the Atlantic when he can quote an exception in a weak attempt to discredit the general with a lone particular, even when the original statement accepted that there were exceptions and made this self-righteous pedanticism quite superfluous. (Sid, nb there's a world of difference between "isn't likely" and "Cannot" or "won't ever". One is an absolute, the other isn't...) Geddit?

My 212 endorsement was done in Tripoli, including night S/E run-ons down the main runway. Lots of bright sparking, and the next day embarrassingly deep grooves in their runway surface.

Thud's dit about using the apron reinforces my earlier advice to look for a hard surface other than the runway, especially if it can provide less of a crosswind :ok:

Wageslave;Maybe so, however you quantified your "not likely", with "millions of European training hours".

As I mention earlier, the instances of rollover during a run on landing are significantly higher on your side of the atlantic, which is probably why you mention 'European' in your statement. :rolleyes:

My old Bell 47 instructor, after an engine off landing where I had made the "spot" by slithering along the grass, said to me:

"Its not the landing that will normally kill you, but the forward speed, so I suggest that you always try to land with the minimum forward speed to reduce the distance it takes you to stop"

I think they were wise words and I have always taken them into account during my 30+ years of flying.

finally, This is a rhetorical question. Except in training, if in helicopter we have an emergency, we choice the closest and most accessible terrain and then manages.
concrete or grass runway ? .... it is very rare to have a choice in real failure!

Most of the time there is NO runway !;)

Thank you everyone for their valuable inputs.

A lot has been mentioned on the subject by Shawn Coyle.
Little book of Autorations.

Chapter 11.Pass on the Grass....

Intresting read.

If it helps, you can read it here;

https://books.google.co.uk/books?id=...0grass&f=false

When I went through the US Army Helicopter School.....One Skid Length was the maximum acceptable standard for ground slide.

Mind you we did do some the entire length of the heliport when wagering who could slide the longest distance.

But as noted....in helicopters the slower you are at touch down in both vertical and horizontal directions the better off you are.

lots of passenger terminals have flat roofs? No interferance with other aircraft and you can quickly get down the stairs to the airport bar?

:ok: Best answer in the thread, when "tongue in cheek" is considered.