Empty United 767 rolled uncontrolled across tarmac at Santiago (SCL)
Dec 30, 2021, 1:10 pm
#16
Join Date: Feb 2002
Location: BNA
Programs: HH Gold. (Former) UA PP, DL PM, PC Plat
Posts: 8,185
Yes. It's not a separate brake system. To set the parking brake, you hold the brake pedal and activate the parking brake system. That traps the hydraulic fluid that you were applying by holding the brakes so that the brakes will continue to be held when you release pressure on the toe brakes. The system has a hydraulic accumulator which aids in maintaining that pressure.
For a tow, you would run the APU to provide electrical power to run the electric hydraulic pumps to provide the hydraulic pressure for the brakes.
The move teams have their own checklists that they follow when moving or taxiing aircraft.
For a tow, you would run the APU to provide electrical power to run the electric hydraulic pumps to provide the hydraulic pressure for the brakes.
The move teams have their own checklists that they follow when moving or taxiing aircraft.
Dec 31, 2021, 7:11 am
#17
Join Date: Aug 2008
Location: PHL
Programs: UA 1K 1MM, Marriott Gold, IHG Platinum, Raddison Platinum, Avis Presidents Club
Posts: 5,271
Hmm. Assuming max landing weight of a 767 at 350,000 lbs / ~160,000 kg, moving at just 1 meter/sec = 3.6 kph = 2.2 mph, instantaneous momentum is 160,000 kg-m/s (p = mv) and kinetic energy of this system is 80,000 J.(KE = 1/2 mv^2) or about 8% of the explosive power of a stick of dynamite.
Any screwup such as the broken tow bar embedding itself in the tarmac or dirt or vehicle/human would have a deleterious effect on the thing that stopped it.
Not a good idea.
David
Any screwup such as the broken tow bar embedding itself in the tarmac or dirt or vehicle/human would have a deleterious effect on the thing that stopped it.
Not a good idea.
David
Since it was between flights, I would guess it would be closer to operating minimum weight, so maybe around 240,000 lbs. with fuel and other stuff in the cabin/cargo hold. And it definitely looked like it was going faster than 2.2mph.
But yeah, letting it run out was probably the best course of action provided it wasn't going to interfere with any active taxi or runways. You also figure the mechanics would know how to operate the manual brakes on any airline they're certified to work on.
But yeah, letting it run out was probably the best course of action provided it wasn't going to interfere with any active taxi or runways. You also figure the mechanics would know how to operate the manual brakes on any airline they're certified to work on.
Anyways, it must have been an interesting ride for whoever was in the cockpit. I would think that job (or that portion of the job) would be pretty boring day to day.
