Tug driver killed Bangkok Feb 2020
 

https://www.bangkokpost.com/thailand...-at-don-mueang
see link for video

How, can this happen. Why was no one required to be in the cockpit to apply the brakes when needed?

A number of operators are starting to use a dark flight deck when they are having aircraft towed, i.e. nobody on the brakes. This is a sad but classic example of why that is not a good idea. If the DFDR was running during a tow, you could use FDM to see how fast aircraft were being towed - I have seen some going faster than when taxied. If a shear pin goes or the aircraft otherwise escapes from the tug, you have an immediate problem, as this poor guy found out. The other moral of the story for tug drivers is to accelerate, not brake, if tug and aircraft part company unexpectedly.

It is standard practice to tow aircraft with the flight deck unmanned. The accident you witness in the video has happened many times often when towing downhill on a slight incline. The aircraft has much more momentum than the tug. If the tug goes too fast and then attempts to reduce speed all the braking load is borne by a towbar that is effectively a simple shackle hinged at both ends. If the towbar is not perfectly straight when braking the whole rig jack-knifes, the nose leg castors with the towbar and the tug & driver end up facing rearwards squashed beneath the forward fuselage. If you look around many older 737s have some skin damage about a towbar's length behind the nose gear leg where this has happened.

[QUOTE=Magplug;10688440]It is standard practice to tow aircraft with the flight deck unmanned.

But I'll bet it's not SOPs.

I have seen it done on numerous occasions, and I don't like it.
All the AMMs and Ops. manuals will require a person on the brakes or an alternative procedure if things get out of hand. ie. people with chocks near the wheels.
I have had one case of an aircraft rolling away from me when the towbar was disconnected as there was no brake pressure. It's quite scary. (Chocks saved the day).

it is SOP when its a towbarless tug.

Never heard of a single-man tow using a tow-bar; the risks are simply too high. Totally different when using a TBL. Question is, though, whether a person riding the brakes would have made a difference, as he/she may not have realised the linkage had broken before the aircraft crashed into the tug.