It has a human driving it when it's not attached to the plane, and the pilot controlling it when it is.

In the current AI madness you really can't make anything that's not AI driven. And even if it's not, you have to name it like if it actually is. So, name it "bot" even if it's just a human-driven vehicle.

Thermal cycles are stressful things for engines, especially going from idle to takeoff thrust. Presumably this means that the engines will still need to be started some minimum time before reaching the runway. If HERON becomes a common thing it'll be interesting to see if there are more rejected takeoffs or engine failures and emergency landings.

Tugs are slow, the need to dispose of the tug in a place where it can easily return to the apron without causing congestion on taxiways or the runway will perhaps limit this at some airports.

You are right, they will probably have to start the engines anyway some time before takeoff, but still they can probably save some fuel by doing it at the last moment and just for the right amount of time to make them work properly. Overall this can lead to fuel savings, especially if there is some kind of congestion and so the planes have to wait in line with engines running (as of today).

Not just at the last moment, but presumably only to idle speed, whereas taxying under own power would require some thrust above idle? The airliner world tends to be conservative and needs to make pretty accurate fuel calculations, so if they are claiming to save "half the fuel" then this must be what they are seeing in practice.

M.

Only two-three minutes for a modern gas turbine aero engine on a single aisle aircraft to warm up from cold. In my experience as a passenger, engine start to take off is usually a LOT longer than that.

Proper warm up for a CFM equipped A320 is 2 minutes if it has been shutdown for less the 2 hours, and 5 minutes if longer than 2 hours. Your start the clock when the second engine is started, usually the chrono timer, and its checked before you line up. Unless your gate is near your runway, not usually a problem. Feels like a solution in search of a problem.

Also looking at the very long taxi times at some airports is this going to increase the time from the current pushback to power tests before entering the runway?

I would be surprised if the vehicle supported the same taxiing speed as the aircraft under it's own power.

LOL, I like these random-made "non strictly positional" acronyms. Just take any letter from the words you like more, and the hassle of making up a proper acronym is gone.

Better call it EGO (Efficient Green Operations) at this point.

Should they be bird from naming more things?

From heron in, yes.

For me it's been throwing times wherever you feel like in the sentence.

> Last week, Airbus revealed it has certified a “Taxibot” to transport its single-aisle planes from stand to runway.

> Airbus last week revealed it has certified a “Taxibot” to transport its single-aisle planes from stand to runway.

> Airbus revealed it has certified a “Taxibot” to transport its single-aisle planes from stand to runway last week.

> Airbus revealed, last week, it has certified a “Taxibot” to transport its single-aisle planes from stand to runway.

> Airbus revealed it has certified a “Taxibot” last week to transport its single-aisle planes from stand to runway.

> Airbus revealed it has certified a “Taxibot” to transport last week its single-aisle planes from stand to runway.

> Airbus revealed it last week has certified a “Taxibot” to transport its single-aisle planes from stand to runway.

> Airbus revealed it has last week certified a “Taxibot” to transport its single-aisle planes from stand to runway.

choose your favorite placement of time. Choose what you've been seeing most commonly lately. Choose the "Wtf? Why are people DOing it like that?!?" Honestly almost all of the lines above are better than what is used in the article.

The position does affect which part of the sentence happened last week. Common sense can override that, but the default meaning of your third variant is certainly not better than what's in the article.

Back of the envelope calculation for somewhere like Heathrow where there are 250-ish short haul departures per day from BA alone (according to Google). Average taxi time is 25 minutes, so given a 5 minute warm-up and a bit of flexibility, the saving per flight will be 15 minutes. You can only count the saving of one engine (because they're already using one-engine taxi procedures), so that's 250 * 15 minutes * 500kg/hour of fuel, so approximately 31 tonnes of fuel per day, or 11,000 tonnes per year. That's 35,000 tonnes of CO2.

Throw other airlines into the mix (Air France, Lufthansa, Iberia all use A320s for short haul because the 737 is crap) and the benefits get even better. There are, however, some quite big challenges associated with the implementation, namely that if it doesn't release from the aircraft then you have something stuck in quite an inconvenient position and holding everything else up. Faults tend to present on Airbus at first engine start, so doing that in the queue for take-off is not ideal. None of these are insurmountable, though.

Don't forget that the 'taxi' uses fuel as well, so it's not completely eliminating emissions. It will be significantly lower though.

Add in the cost of another attendant driver and another machine that needs maintenance. I'm not sure how much sense it will make financially, but pleased to see that they're looking to improve what can be improved.

the plane burns kerosene and I assume the taxi burns diesel. which is cleaner?

That is a question for Greta Thunberg....

I assume the taxibot thing uses batteries.

From TFA:

“ Taxibot’s maker plans an all-electric version of the vehicle to debut in 2026 and is also working on a version to haul widebody jets. ”

Presumably it will very soon also get certified to tow from the runway to the stand as well which could double those fuel savings

The trouble with "runway to stand" towing is that there's no good point to hook up the tow, which takes some time. For efficiency and safety reasons, aircraft have to move off the runway as soon as possible. Most major airports have slanted taxiway exits that allow exiting the runway at increased speed even. Aircraft then have to basically keep moving as the aircraft landing behind them might well use the same exit and need the space. So there's not really a good point in that travel to stop, wait to attach the tug and then continue again without potentially being in the way. There might be ways around this in some airports but those will likely be the exception, not the norm.

? Still trying to get my head round that one.

*Technically* they aren't throttling the engines up for taxi, and might even turn them on a little later.

Virgin Atlantic tried this years ago, towing their 747s by the nosewheel to the runway hold point to save fuel. After a couple of weeks Boeing told them to stop doing it as the nose gear wasn't stressed for it.

I was going to say the say about Virgin, I didn't know that was why they stopped it though

Perhaps the manufactures can beef up the nose gear and airframe... in preparation for catapult take off of passenger aircraft!

Alternatively, there's always JATO/RATO...

[1]https://en.wikipedia.org/wiki/JATO

[2]https://www.youtube.com/watch?v=BnUsAJyPuyg&t=5s

[1] https://en.wikipedia.org/wiki/JATO

[2] https://www.youtube.com/watch?v=BnUsAJyPuyg&t=5s

This is why Airbus is certifying its planes for this. Because they have to make sure that the front (wheel) does not fall off.

[1]Yeah, that's not very typical, I'd like to make that point .

[1] https://www.youtube.com/watch?v=3m5qxZm_JqM

A 747 is in a "slightly" different weight class to an A220 or A320 series aircraft. It's probably one of the things that needed to be certified, but I would imagine it's comparatively far less of a problem on a single aisle narrowbody compared to the stresses put on the nose gear strut of a 4 engine wide-body.

Hopefully they have a robust protocol to notify the pilot when the bot is clear of the runway.

I saw the headline and assumed that they'd come up with a unit that didn't need a driver; something like, a driver takes it to the gate and hooks it to the plane, then gets out. The pilot remote-steers it to the runway, where it disengages, and then returns autonomously to a parking space for the next go round.

This is - a driver drives the tug to the plane and hooks it up, the pilot steers it while the driver sits there, the driver unhooks it and drives it back to the apron. Which is exactly as it is now except for the pilot doing the steering. Still need one tug and one driver for every taxi out.

AFAIK the tug nowadays only pushes the plane back from the gate, and then the plane uses its own engines to move to the take off line. So the idea here is to tug the plane around while on the ground and not just push it back from the gate. Still I'd totally expect the tug to be an actual bot, so as you say it should come back on its own, at least. It was probably the original idea but it got scrapped because it's not safe enough.

I suspect in future they'd want to make the tugs autonomous for the "not towing an aircraft" portions of this rigmarole. But aviation is never going to accept driverless vehicles hooking up to jets and whizzing around on the apron without exhaustive testing. Airbus probably wants to get the use of tugs for these purposes normalized first before they start trying to take the next steps towards making them autonomous.

This idea has been around for years. Here is a version from 14 years ago:

https://www.youtube.com/watch?v=6HxrUm9s8NI

That is the very first testing of this exact Airbus idea. Except that Airbus has now actually certified this for actual use and it's no longer experimental. So there IS something to see here.

The only thing I have to wonder about is how they're going to run AC systems when the engines remain off after pushback. Right now the standard is that the aircraft is on ground power and usually external cold air supply until push back, after which the passengers get a little uncomfortable until the first engine is started.

Do they now run the APU for bleed-air and power until they reach the point for engine start? That's going to put a lot more hours on the APU with related fuel and service costs. I have to wonder if that consideration is taken into account in the cost analysis by Airbus

APU tends to be used pretty much exclusively when passengers are on board. The fixed ground air system can just about keep an empty aircraft cool on a hot day but can't cope with a 200 people squished into a metal tube.

My experience (and that of a few friends, some of which are airline pilots) is that unless it's a really hot day, they (especially the low-cost carriers) keep the APU off anyway and just let the passengers and crew suffer until engine start anyway. By that time you're usually glad when the engines start and cool air starts circulating.

If they can get this working with electric motors (or at least hybrid) then another plus is the definite potential to improve safety and air quality on the ramp - although I love the smell of burning jet fuel - engines often burn oil and other crap when starting up, and if you're working on the ramp every day it's probably going to take a toll on your health.

If each aircraft just has to start a relatively small APU with an exhaust that's high up, rather than starting two or more jet engines down at person-height, I'd expect that would make a difference. Don't start the engines until you're on the taxiway out in the open and the startup smoke dissipates where there's nobody to directly breathe it in.

Could also reduce the likelihood of foreign object damage, as well as reducing the likelihood of workers being ingested into running engines.

All low probability, but high cost/impact issues which probably add to the overall business case.