Landing on sand?

[double_barrel]

Hi All,

Most of my flying at the moment is along the Kenya coast with miles (and miles and miles) of deserted beach as the obvious place to put down in case of an engine fail. However, having walked on the sand, its condition varies massively with the state of the tide. When the sand has been dry for some hours, ie near the bottom of a low tide, it is very firm and would make a beautiful runway. In that state it's like flying with a runway always in easy gliding distance.

But, when the tide is higher, even though there is still plenty of sand exposed, the same piece of sand has very deceptive characteristics. There is a surface crust of hard sand, but as soon as you stand on it, you break through and sink perhaps 6 inches through very soft sand underneath. I don't know how the hydrogeology (?!) of how that works, but I guess that the water is evaporating rapidly off the top and retreating from below, and it takes time for it all to equilibrate and compact firmly. Trying to land on that would I am sure result in an instant flip with nasty consequences.

It's impossible to tell the difference while flying. I do know the state of tide, but I don't know how quickly different parts of the beach change characteristics. I wonder if anyone has any experience of this and any thoughts on what you would do in these circumstances in the event of an engine fail ? I should add that further inland there is usually nothing but miles of horrible scrub and trees which is not an attractive option. That leaves me the choice of sand or surf. Any thoughts ?

[oggers]

Sand v surf. Sand because you will not flip instantly due to the lift you still have at the beginning of your roll out and aerodynamic control. OTOH if there were people or obstructions to hit on the beach I would prefer surf. When a light aircraft ditches the vast majoirty get out so the question is then how likely are you to drown? Just off a beach, it stands to reason that you will most likely be ok. But I would rather use the beach even if it was likely to result in parking upside down.

[charliegolf]

Sand v surf. Sand because you will not flip instantly due to the lift you still have at the beginning of your roll out and aerodynamic control. OTOH if there were people or obstructions to hit on the beach I would prefer surf. When a light aircraft ditches the vast majoirty get out so the question is then how likely are you to drown? Just off a beach, it stands to reason that you will most likely be ok. But I would rather use the beach even if it was likely to result in parking upside down.

Don't (not saying you are btw) underestimate the disorientating effect of being upside down in the water either. As a very very confident 'water-person', I was amazed at the effect of this when I used the Navy's 'dunker' tank- strapped in with a psp on my back. It's an eye opener.

CG

[sycamore]

Depending if it`s your aircraft,bigger ,fatter tyres might be an answer..personally ,I would aim,in an F/Ldg to land nearest to the waters edge,irrespective of tide coming in or out.
Another alternative used by `old early `bush-pilots` was to use skis,as they could be used on muddy surfaces,beaches,river sandbanks,before the trend in `balloon tyres`...not sure about skis on a nosewheel a/c, but `pilotDAR` will be able to advise..I know it sounds ridiculous in Kenya,but you could try Kilimanjaro landings.....

[Piper.Classique]

Ready for a laugh? Amphibious floats...
Of course there would be extra drag. Rather a lot of extra drag, actually. But they land wheels up on land usually without damage. Doesn't work the other way round, though. Wheels down in water would be a pretty reliable way of going tits up.

[slacktide]

I occasionally fly in and out of Copalis State Airport, the only officially designated beach airport in the USA. https://wsdot.wa.gov/aviation/AllStateAirports/CopalisBeach_CopalisState.htm This beach is ideal for aircraft operations because it has a very shallow slope, and the sand is fine and densely packed. So, during a falling tide, a large band of the sand is wet enough to support aircraft operations, and not just bush aircraft with big tires. I have seen plenty of Cessnas and Pipers with 6" wheels, and aircraft as large as a Beech 18. Overall the recommendations for operating here would also be applicable to selecting a location for an emergency landing site on an unknown beach.




Check local tide tables.
Dark, wet sand at low tide is the hardest for landing.
The dry, light-colored soft sand near the high tide mark should be avoided.
Summer landings may experience softer wet sand area (less compact) and higher risk of getting stuck.
Avoid operating in the razor clam beds.
Over flight is recommended before landing to check for obstructions such as exposed rocks, debris and pedestrians.
The landing area is shared with other beach users and activities.
Park aircraft in a row along the high tide mark.
The busiest time is during the summer months and during the winter clamming season.
Announce your intentions on the common radio frequency.
Do not park aircraft overnight due to tidal changes.
Observe all state park regulations.

[blind pew]

Have done a fair few gliding expeditions to Kerry where we auto towed the gliders off the beach.
The sand is a problem for the first hour or two after the tide has retreated but soft sand or wet sand where a stream runs across the beach was never a problem for glider, car nor trailers. Cable ..parafil..digging itself in was so we zig zagged the tow car during cable retrieves.
Only special procedure was a lump of plywood under the wheel before take off to stop the wheel sinking into the sand. Once moving there wasn't a problem.

[Maoraigh1]

I've done very few beach landings, and ALWAYS someone had checked the beach first.
I've done a lot of beach walking.
Onshore wave action changes the firmness.
Wind dries and blows sand.
Beach airfields are likely to have firm sand. Some beaches are much more variable, affected by recent wind and wave action as well as the tide.

[Pilot DAR]

If you are choosing to land on a surface other than a hard surfaced runway, you have to take responsibility for assuring that it will support the plane. This includes grass and soil, sand, gravel bars, snow, and frozen bodies of water. Walking the landing area is a very good start, and I have certainly done this in some cases. But, while you're flying, that's not so easy.

What I do in preparation for such a landing on an unknown surface will be:

First, assess the whole area - as trained to me during helicopter training, fly a high reconnaissance, and consider the area as you would consider a prospective date: Suitability, surface, slope, sufficient, surroundings, and wind. If all of those seem good;

Second, fly a low reconnaissance, get a better look at surface and approach/departure paths. If you see standing water, best give it a pass. During this pass, consider your proposed landing and takeoff area. If there is enough space, make your takeoff area continue from your landing area, so a backtrack is not needed. Remember the landmarks which define this area.

Third, (and this is the tricky part): Land one mainwheel only, and run along, ideally the whole length on that wheel only. This will be easier in a crosswind. Now doing this on a hard runway will result in a lot of squealing tire sounds, and angry stares, but on a soft surface, it is harmless to the plane. With only one wheel down, the plane is still flying the whole run, you can pick the plane off (out) in an instant, and are not committed to land. If you feel that mainwheel drag, the surface is too soft, don't land. I you run the landing and takeoff path, and it seems good, fly over, and look for your own tracks.

Fourth, Land again with both mainwheels on, but holding the nose (or tail) wheel off the whole run. Again, feel for dragging, and go around, and look for tracks or marks. If, after those runs, you're happy, you should be okay to land and stop.

It sounds like a lot of effort, but I have done this each time I've landed away on a remote beach, I've done this. Similarly on unbroken snow, both on wheels and skis. A few times on snow, I've felt the tug, or flown back over and seen bad areas in my tracks, and not landed. Every beach landing I have done worked out well.

Remember, if you're choosing to do this, you may be a long way from help, and any small problem becomes big fast. So, make sure it's worth it, and have a plan.

My 150 on a beach on a Georgia (USA) island. You can see my two wheel marks from the previous run before me - my departure path....


https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/1600x1200/img_0140_9e6ba2bac212a28c088e12102855ff71f6e12259.jpg


If you want to research this more, search about "California bearing ratio" it describes the capacity of various soils.

[double_barrel]

Thanks all. Just to be clear, I am considering options in the event of an engine fail, not planning a deliberate landing.

Here is a photo of an example, this is on a rising neap tide perhaps 2 hours after low water. In this situation I think the beach (with very soft sand here) is the only realistic option because the large area of very shallow reef would be lethal. With a higher tide, I think I would go for the water here. In other places there is deeper water off the beach and the surf would be an option.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1349x779/beach_cbe56c0e72e8f028eeb82aef4b4f69686f6d908a.png

[sf25]

There's an airfield on a beach in Scotland, regularly served on behalf of flybee twice a day accordingto this article from 2016 - at least at low tide. Three marked runways, check-in building ...

https://www.aerotelegraph.com/barra-airport-schottland-hebriden-merkwuerdigste-flughafen-der-welt-feiert-geburtstag

[Jn14:6]

FlyBe (q.v.) ceased operations in early March.

[jaycee46]

It is, and I think always was, operated by Loganair, whose planes used to be painted in FlyBe colours due to the franchise arrangement. Now operating in their own colours, up to twice a day, depending on the tides.

[Maoraigh1]

The HIAL Barra Airport staff check the beach runways before opening- note thr SUV tracks when landing.

[Pugilistic Animus]

Just to add, crack the door open to prevent the impact from jamming the door shut.

This is a very good thread, here in the practice airspace the beach is very close and would make an ideal landing spot for a gliding airplane. I have always wondered exactly what this thread answered for me, I know where to land but I'm not quite sure how to land.

[Sam Rutherford]

We needed engineers to sign off our sand runway for the Zoute Air Trophy. The sand between the high tide mark and the actual sea was good or excellent at all times - though the sand nearer high tide just before high tide was slightly softer (had enjoyed the longest opportunity to dry out). Whilst the slope of your beach is manageable, the hardness will also be fine in this 'zone'. The only other thing to watch are the washouts - water running down from pools higher up the beach which create little streams - which create drops/climbs in the sand of up to 20cm (across your landing direction).

In contrast, the soft sand higher on the beach was extremely unforgiving during the taxi phases - requiring extensive ground handling (and some of the pilots who were too enthusiastic with the throttle and too impatient to wait for a pull/push managed to damage their aircraft).

If you have the opportunity, try it! Don't forget a good wash afterwards...

[abgd]

There was a Turbulent ditched in shallow water in the UK recently, and the pilot was unable to get out by himself as the aircraft came to rest upside down on the cockpit. Luckily it was an airshow and he was rescued.

This has completely changed my views on potential water landings. I would now either choose to land on a beach or further out to sea, but never in the surf.

If I were flying a high wing aircraft such as a 172 I would be more likely to choose to land in shallow water.

[Peter Geldard]

The HIAL Barra Airport staff check the beach runways before opening- note thr SUV tracks when landing.

It is a well proven airfield which works remarkably well.
You need to PPR to obtain the 'tide timetable' i.e. the hours that landings are available and/or the timings of commercial flights.
The runway is inspected by the local staff each time and the landing is quite smooth.
I would advice a slightly higher speed to transit the water puddles that always remain.
If you can, at your next airport, try and get the fire brigade (or their permission to use their water supply) to hose the wheels to remove residue sand getting into the bearings/brakes.

[oggers]

Don't (not saying you are btw) underestimate the disorientating effect of being upside down in the water either. As a very very confident 'water-person', I was amazed at the effect of this when I used the Navy's 'dunker' tank- strapped in with a psp on my back. It's an eye opener.

CG

I was dunker trained in the RN and was also a Sqn SURVO so I have quite some experience.

[charliegolf]

I was dunker trained in the RN and was also a Sqn SURVO so I have quite some experience.

Me too. Well, CSRO in light blue parlance.

CG

[oggers]

^^ as you said disorientation is a major factor. You will be aware that one of the key drills taught is to 'orientate' toward the escape route (for those not actually on the sticks) before ditching. Nonetheless my original point is that even for GA pilots with little or no training in ditching, they are statistically most likely to successfully egress after a controlled ditching as discussed in this video https://youtu.be/0LwGYBBhTss?t=230

[Pilot DAR]

Good video! For my experience, if you see this fellow (Paul Bertorelli) presenting about GA flying, it's worth a listen. To answer his one variable, my experienced choice would be wheels up for ditching an RG.

[possel]

There was a Turbulent ditched in shallow water in the UK recently, and the pilot was unable to get out by himself as the aircraft came to rest upside down on the cockpit. Luckily it was an airshow and he was rescued.

This has completely changed my views on potential water landings. I would now either choose to land on a beach or further out to sea, but never in the surf.

If I were flying a high wing aircraft such as a 172 I would be more likely to choose to land in shallow water.
Yes, but the issue that particular pilot had was nothing to do with the surf. His problem was that his lifejacket inflated automatically when he flipped over, thus preventing him from undoing his harness! He survived simply because he was so close to the shore that onlookers could wade in the surf and lift the aircraft so that he didn't drown.

Moral - aircraft and automatic lifejackets don't necessarily mix.

[Sam Rutherford]

Correction: aircraft and AUTOMATIC lifejackets NEVER mix! Luckily, it's usually possible to simply unscrew the 'automatic' part.

Even better, most of the 'aircrew' jackets are simply more expensive (but less equipped, without the automatic part) than the yachting version. Top tip, head to your chandlers and save a few £££...

[possel]

Correction: aircraft and AUTOMATIC lifejackets NEVER mix! Luckily, it's usually possible to simply unscrew the 'automatic' part.
And I thought If I said "NEVER" I would have some smartie correct me...!

[Sam Rutherford]

:) You're right, sorry. Never say Never.

[Bosi72]

Sand vs water = sand
Rocks vs water = water

In any case away from people.
Air siren may help a bit.. maybe..

www.ebay.com.au/itm/271968017150

[Chris Wheeler]

Good ideas. My friend and I always fly as a two ship, to provide mutual support.

[Chris Wheeler]

I would agree that it would be very disorienting flipping over in water. I fly an F1 Rocket, I think in a forced landing there’s a very good chance of flipping over, even if on land. Unless of course you find a very smooth location. So I carry a military style canopy breaker tool and I’m looking for some device to partially hold my canopy open in the event I’m about to land off airport. Funny, my whole time in the military and airlines, I never worried much about forced landings. But now with my little experimental Rocket, I’m always looking for a potential landing strip.