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Comment by kylehotchkiss | Hacker News Reader

Brilliant, too bad they can't remove seats from the planes to take advantage of upper floor to move lighter/bigger things at good prices. They couldn't get ULDs up there but could definitely stuff a lot of lighter boxes in and tie them down to the floor rails.

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This os currently being done to get critical medical supplies (masks, respirators, coronavirus tests, hazmat suits, etc.) to Czech Republic from China. While we managed to make use of the huge An-124 planes in long term service to NATO to move 100 tons of the stuff at once, the rest is being moved by regular passenger planes - owned by Czech Airlines and China Eastern.

On the photos from the airport you can see Czech firefighters & the army making a human chain unloding lots of boxes from the passenger compartment & of course regular unit load devices from the planes cargo space.

AirSerbia has used two of their passenger airplanes to carry donated medical supplies and personnel from China.

https://www.b92.net/eng/news/business.php?yyyy=2020&mm=03&dd...

The Chinese generosity was excellent here, but at the same time it's disappointing that other European countries couldn't spare any real help for poorer countries nearby.

Post is flown around during night on PAX planes using special seat covers. Used to at least back when I was working at an airport.

But it's good to see that planes are getting backin the sky for freight.We can use every single tonnage right now, especially for urgent stuff. Heck, I am looking for some capacity ex Shanghai right now that's not ruinously expensive.

EDIT: Typo

Seats move around and are replaced all the time. This is how legroom keeps shrinking.

They're probably hoping things will go back to normal fast enough that the cost of removing and reinstalling seats would outweigh the benefits.

Right, but only to configurations that have gotten FAA approval, right?

> only to configurations that have gotten FAA approval, right?

No, the FAA doesn't regulate seating layouts.

Weight and balance have to be met, and exit time is verified.

So ... only to FAA approved configurations, then, as judged by weight distribution and exit time.

No, FAA doesn't deal with configurations. They have regs as to how to balance loads, but that's a hot-to rule, not something you need to get approved or they'd have to approve every single flight. Nothing is stopping Southwest from removign all their seats right now.

The thing is, the FAA and ESA are putting targets for evac times. These have to be adhered to. They are not looking at individual configs, just that evac times are kept and properly tested for.

FYI: In case you're not a pilot, I was being a little ironic about weight and balance.

Since people are heavier today, and carrying unweighed baggage into the cabin, weight and balance are actually not being met.

They're blocking off the last 2 rows on the A320neo because of this: https://www.forbes.com/sites/heatherfarmbrough/2019/09/19/wh...

I'm a commercially-rated airplane pilot. I tolerate the pedantic HN comments, but please realize that I know what I'm talking about, and if you're not a pilot, you don't.

In your mind, if there was only a single rule that seats have to be red, would that count as only allowing "approved configurations"? They have to meet a couple simple measurements, but they can do anything at all inside that constraint, putting seats anywhere they want with nothing stopping them. "approved configurations" just isn't accurate.

Landing slots aren’t a constraint, so maybe it’s good enough to fill the hold and take advantage of the fuel economy of a lightly loaded plane.

Maybe? Planes only have about a quarter of their max weight available for passengers the rest is the plane itself and the fuel so I'm not sure how much you'd save by running light.

Maybe flying slower would be a way to make cargo flights more efficient but planes are pretty tuned to their cruising speed so maybe even that wouldn't have a big effect.

Typical cruise in airliners is about 10% faster than their most efficient speed, which translates to a 15% or so higher fuel burn per distance.

You also do not need to take off with max fuel weight-- and airliners these days rarely do, so that leaves more mass budget for cargo. For the past couple decades, airlines have been really focused on eliminating weight and using the efficiency increases this brings to reduce fuel weight, further increasing efficiency.

Across huge scales, this can have surprising effects. United figured they saved $300k/year of fuel by printing their in flight magazine on lighter paper.

According to their site they ran ~1.6 million flights in 2019 so they saved $0.18/flight which across their operating revenue of $43.259 billion is a rounding error even when it adds up to 300k.

A rounding error, but still worthwhile. $300k here, $300k there, and pretty soon you're talking about real money ;).

Anyways, the main point: passengers and their luggage on a 737-sized craft might weigh 15,000 kilos. You might save 340 kilograms/hour by flying slower, too, so a 6 hour flight without passengers could move 17 tonnes more than it did with pax onboard, so long as you have space for what you're shipping.

Airline seats are bolted down, so they can be removed.

That doesn't give you access to move containers in and out, the doors are very small. Cargo conversion can be done but it is neither cheap, quick or easily reversible.

In times like these temporarily removing seats to allow them to be converted back to passenger planes makes more sense. Even if egress isn't as optimized as a true cargo plane.

Optimized is too small a term. It's neigh on impossible to responsibly load a plane without the required infrastructure in place, weight, balance, shifting loads and so on are all reasons why standardized cargo containers are used. Loose loads in aircraft can have this kind of effect:

https://www.youtube.com/watch?v=p_eP0zdfZFk

So, assuming you can get the load safely in to the plane, without some kind of containerization inside it you are running a significant risk. Note that the video shows a crash due to one or more Humvees not being properly secured and I'd expect shifting loads to be a bit nicer than that on average but still, that's a risk that need not be taken.

Cargo planes are cargo planes for a reason.

Presumably something could be devised that bolts to the now-empty seat rails and provides a way to secure small cargo. It's entirely possible such a solution wouldn't be cost-effective, though.

Nets.

Not for most commercial planes, no. Slightly off topic, as the number of planes is very small, but I have seen Russian load masters of old Russian military cargo planes applying some, let's say creative, ways of loose loading them.

I still prefer the properly controlled and planned way, so.

> That doesn't give you access to move containers in and out, the doors are very small. Cargo conversion can be done but it is neither cheap, quick or easily reversible.

True, but it would allow workers to use a dolly to easily and more efficiently load small pallets of larger items (compared to carrying them in by hand and trying to buckle them into a seat or something).

Maybe they could use also use the seat attachment points to somehow secure the cargo.

Yes, that is how it is typically done, they throw nets over segments of boxes on the floors and secure them to the seat rails.

The German postal service is still paying for a couple of flights during the night to make sure it can guarantee E+1 delivery. They use regular passenger planes with a special set of seat covers: https://www.youtube.com/watch?v=GKORFvrttPo

That's a super neat solution and still uses quite a bit of the capacity of the plane. Looks very stable too.

I imagine they could pack dense/heavy cargo in passenger planes and leave the lighter stuff for proper cargo planes.

Presumably there’s no serious flight issue with planes being bottom heavy.

no, but if the plane is not fitted with restraints and the cargo shifts, it's game over.

Presumably they'd be using aircraft with unit load devices rather than something like the 737 where the luggage compartment is arranged by hand.

I read not long ago that the 747 was designed specifically for this purpose, in case the design failed for passenger use it could be repurposed.

You are right...but there is a bit more to the story. The 747 program was launched on the back of a failed bid to design a cargo airplane for the military, the Lockheed C5 Galaxy was the winner. This failed military transport design was then picked up and was the basis from which the 747 team started work. This is the reason that the cockpit is on the upper deck, as opposed to the lower deck as in the A380, one of the design requirements for the military transport was a front loading bay and a cockpit on the lower level would not have allowed that.

You are right that the 747 program definitely considered both freight and passenger versions throughout their design process, but that was pretty much assured from the start given that the plane they designed had its roots in cargo.

I have also heard the Boeing believed that supersonic airplanes would become de rigeuer for passenger travel within 10 years or so, so they made the 747 freight-capable so they wouldn't be completely worthless in the future.