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Parking airliners on soft ground

Posted: Sun May 10, 2020 11:00 pm
by mxaxai
So this image got me wondering:
BNEman wrote:

Usually airplanes are parked on proper parking areas with a concrete or asphalt surface - ramps, taxiways, runways etc. The only exception is aircraft that are "stored" in the desert but those are usually there for scrapping anyway. However, SQ is clearly not planning to retire all the aircraft at ASP in the image. At least the 737MAX and the A380 will return to service and even the A320 have a decent chance. So what are the procedures for parking such heavy jets on unpaved ground? You wouldn't want them to sink in like the BA A380 did on that taxiway shoulder.

Can the aircraft taxi their under their own power or is a tow required? Would it ever be permitted to perform regular operations from a runway or taxiway like that, without a dedicated gravel kit?

How is the strength of the ground assessed? How can the airport guarantee this strength, since these "taxiways" are subject to erosion and natural variation of soil strength?

Is there a required 'smoothness'? There seem to be some bushes growing on these "taxiways" and I would expect wind and water to easily create potholes.

On return to service, do the aircraft need a thorough cleaning just in case dirt got into delicate parts, like the gear and engines?

Re: Parking airliners on soft ground

Posted: Sun May 10, 2020 11:53 pm
by GalaxyFlyer
I would guess they’re towed into position. Probably pretty high California Bearing Ratio surface there. I’m sort of amazed at this.

Re: Parking airliners on soft ground

Posted: Mon May 11, 2020 11:04 am
by VSMUT
mxaxai wrote:
Is there a required 'smoothness'? There seem to be some bushes growing on these "taxiways" and I would expect wind and water to easily create potholes.


Potholes are usually created by stuff rolling on the surface. Apart from the odd service vehicle and the aircraft being towed into place to start with, these surfaces see little to no activity. Alice Springs probably doesn't get a lot of water.


mxaxai wrote:
On return to service, do the aircraft need a thorough cleaning just in case dirt got into delicate parts, like the gear and engines?


They might do it, but even runways and taxiways in big European airports can be pretty dirty. I have a photo somewhere at home of an aircraft I flew at the start of my career. The entire rear fuselage aft of the main wheels was covered with dirt picked up in the winter. The reverse thrusters kicked up a lot of crud too, a lot of which must have been ingested. The aircraft only flew between major international airports in Europe. Aircraft work just fine with even a generous dose of dirt on the landing gear. A light dusting of desert dust is nothing.

The engines should be covered up, so they won't be affected in the desert.

Re: Parking airliners on soft ground

Posted: Tue May 12, 2020 12:44 am
by JayinKitsap
Rounded material like sand and pea gravel would not be good, very easy to displace. Crushed rock does much better as the pieces interlock. City streets are typically 3 to 4 inch of Asphalt concrete, basically graded gravel with a high melting point oil comprising 5-6% by weight the material. Mixes are designed to get the best performance with the available materials. Below the AC is a 6" crushed rock base that is on the compacted subgrade. The native soil has various structural capacities that can be derived by test. Up thread the CBR is mentioned. This is a test method that provides relative values of the strength and deflection of the surface, so the proper base and paving section can be selected. In building design I've worked in swamps where a 300 PSF bearing was optimistic, also have been on sites where we blasted out the rock to place the building. With caissons, I have seen bearing values over 120,000 PSF. in solid granites. Out in the desert a static wheel load of the gear are no problem, basically the same as being on asphalt.

Re: Parking airliners on soft ground

Posted: Tue May 12, 2020 7:30 pm
by planemechanic
Aircraft parked on soft surfaces are usually parked on large thick steel plates, to distribute the load.

Re: Parking airliners on soft ground

Posted: Tue May 12, 2020 8:21 pm
by DiamondFlyer
I know that at my airline, when we park airplanes for long term storage in IGM (Kingman), it's not uncommon for the pilots to be met with a "follow me truck." They generally follow that truck out into the desert parking spot they have designated and shut it down right there.

Re: Parking airliners on soft ground

Posted: Thu May 14, 2020 2:03 pm
by Florianopolis
Airplanes sink into "hard" pavement all the time, too. Asphalt in particular.

Re: Parking airliners on soft ground

Posted: Fri May 15, 2020 5:49 am
by rjsampson
Florianopolis wrote:
Airplanes sink into "hard" pavement all the time, too. Asphalt in particular.


Case in point:

https://www.lotustechnologies.dev/wp-co ... 5/sink.jpg

Re: Parking airliners on soft ground

Posted: Fri May 15, 2020 1:28 pm
by citationjet
planemechanic wrote:
Aircraft parked on soft surfaces are usually parked on large thick steel plates, to distribute the load.

The A380s in the photo do not appear to be parked on Steel plates, but on bare ground.

Re: Parking airliners on soft ground

Posted: Fri May 15, 2020 7:27 pm
by 889091
How full are the tanks of the parked aircraft? 1/4 full? 1/2 full?

Re: Parking airliners on soft ground

Posted: Mon May 18, 2020 10:04 pm
by sho69607
Atlas Air regularly stores their unused 747's in KMZJ. Looking at this photo, not only are the engine covers open, but nothing is sealed either. Unless this aircraft is parked for permanent storage, I wonder how they get it operational again. Pressure wash the engines? I do not have much knowledge of aircraft maintenance so I am not sure how sensitive aircraft engines are to the elements.

https://www.jetphotos.com/photo/9711406