Out of curiosity:

Why can’t planes get de-iced at the gate?

I was on a flight from the Central Terminal at LGA recently. All passengers boarded and then the plane moved only a very short distance (we still seemed to be at or next to the gate, although the flight showed as “departed” so the door had closed), and then it took 45 minutes for de-icing, making the flight late.

I assume it wouldn’t work to de-ice a plane while baggage is being loaded, or maybe the de-icing equipment can’t fit at the gate while the plane is connected to the jetbridge, but why can’t someone develop technology to allow a plane to be de-iced while passengers are boarding at the gate, to save time, if a plane can’t be de-iced at the gate now?

Deicing while boarding is impractical because it only lasts for a certain time period once the initial spraying begins. The time it is good for depends on both the outside air temperature and the concentration of the glycol (typically it is 50% water but that can change). Anti-ice might also be required.

On the other hand, it’s nasty, slippery stuff and no one wants to walk or operate equipment around it.

I have been on planes in the US that were de-iced the gate. SEA does it. LGA did it but that was 25 years ago.

The planes need to be ready to roll right after de-icing or else a second de-icing would be needed, especially in extremely poor weather.
You don't want to be near the fluid that is used to de-ice planes without safety clothing or snug inside an aeroplane with doors closed.

Two excellent reasons. I can add one more...............gate space is at a premium.
For those who haven't seen it, YYZ has a dedicated de-icing area where de-icing fluid gets recycled.

You can only deice in locations where the runoff can be collected and processed. You can't let the runoff go into the water table. At some airports that includes some gates. At many airports it does not.

Even when you can deice at the gate that can cause other problems. The fluid is thick, slippery, and runs off slowly. The ramp crews and equipment have to continue to work at that gate for subsequent flights. There is often little room for the deice trucks in the gate area. During icing conditions with the associated delays, there is often another flight waiting for the gate to vacate so they can park. If the frozen precipitation is ongoing, the hold-over times (from the start of the final anti-ice application until takeoff) is short so the time from deicing to takeoff is limited. When there i a lot of deicing ongoing it is more efficient to have all the deicing equipment in a central location so that each crew can deice more aircraft.

For all these reasons, the specifics of the deicing procedure will vary from airport to airport and even at the same airport as the severity of the weather conditions increase.

It is certainly possible to deice aircraft at the gate and at some locations it is the routine. But, not until the aircraft is buttoned up with cabin doors and baggage holds sealed. That stuff is poison.

More importantly, it's not a matter of simply deicing, but only allowing a specific amount of time ---- which is weather dependent --- to elapse between deicing and runway departure. It does no good to deice an aircraft which must be airborne in 20 minutes, at a time when one knows that it won't be for 40 minutes.

Unfortunately I was stuck on a plane at SEA a few years ago that had to deice several times. They kept deicing, then missing window of acceptable departure time. They could not turn on the air, and it was god awful hot and muggy in that plane. I think it took a couple hours before we were finally able to depart.

At ORD a few days ago, the airplane was deiced at the gate. My inbound flight was highly delayed waiting for the gate to open, for about 1,5 hours. Then the next flight was late to the gate for the same reason. I arrived at my destination 5 hours late.

Stationing deicing equipment in one place is better. I was also wondering about employees in the gate area. Deicing fluid is slick / slippers and nasty.

Five years ago, in January 2013, I was on an A380 of EK at AMS after snowfall. It got de-iced just at the gate, before the ride to the runway. The doors were already closed.

We were de-iced at the gate in FRA the other day, but at the same time there were also aircraft being de-iced adjacent to the end of the runway.

I believe it's really an issue of recycling.
In the old days, for airports that had to deice often, it was done at the gate. It's pretty much similar to the antifreeze we put in our cars.
By the 1980's it was clear (for the most part) that under certain conditions of wet, heavy snow, deicing had to be done within a certain time before TO.
In the last 15 years, recycling the deicing fluid has taken priority in some locations.

This more recent recycling, coupled with the fact that all planes are deiced in any kind of frozen precipitation (whether needed or not) for the last 30 years, means increased delays.

Probably because by the time they pushed and reached the runway threshold, they would need to de-ice again. Especially at a busy airport. The fluid is only good for a short period.

De-icing at the gate means wasted resources (gate space not available for another plane). Deicing pads, such as at DEN, that the plane passes through along the way to the runway allow for easy collection for recycling and less elapsed time until takeoff.

When too much time passes after being de-iced, the plane has to be de-iced again. USAir 405 crashed after takeoff from LGA for that reason.

https://en.wikipedia.org/wiki/USAir_Flight_405