View Full Version : UA 777 too heavy for two tugs
krautland
2nd Jul 2021, 10:59
https://www.youtube.com/watch?v=UzC9K1x9z1U
Wonder if this happens frequently?
Equivocal
2nd Jul 2021, 11:56
Not helped by the contamination on the stand.
Yes. I'm also surprised that these tugs aren't all wheel drive. Or at least driven by the wheels under their engine compartment.
Longtimer
2nd Jul 2021, 15:12
no worse than during winter conditions. Perhaps more due to a lack of tread on the drive wheels. :)
Opsbeatch
2nd Jul 2021, 15:14
Should read "Wrong tug used to pushback 777"
Meanwhile, in Russia ...
https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/812x368/russianpushback_7e8bf313e662711c60c9144f66ef53a7c5e1e66b.png
surely not
2nd Jul 2021, 16:47
Spot on. The ground services guys have made a basic error here
Check Airman
2nd Jul 2021, 17:20
So the first tug was just pushing the second one? If I haven't seen it all, I must be getting mighty close.
Wow, there is so much going wrong here it's hard to know where to begin! Talk about amateur night.
tdracer
2nd Jul 2021, 18:12
During flight tests of the 747-8F, they were operating one aircraft out of Victorville. They put the 747 in a hanger to do some work, when it came time to move it back out the first tug wasn't powerful enough to move it, so they parked that tug outside the hanger at got a bigger one. Except that they didn't move the first tug far enough - as they pulled the 747 out of the hanger, one of the engine nacelles struck the first tug...:ugh:
Fewdoom
2nd Jul 2021, 19:12
That's the transmission smoking not the tires.
Deltasierra010
2nd Jul 2021, 19:29
Those tugs are supposed to be 4wd and 4 wheel steer, ballasted they can easily do the job
crunchynutter
2nd Jul 2021, 20:03
What seems to be just as shocking is the traffic passing behind a moving aircraft with anti cols on.
CaptainMongo
2nd Jul 2021, 21:22
It is a push which starts and ends in the non movement area.
NutLoose
2nd Jul 2021, 21:25
That’s all well and good flooring it and wheel spinning the tug, right up until it suddenly finds some grip.
WillFlyForCheese
2nd Jul 2021, 22:45
Two tugs? The second was a baggage cart tug . . .
:rolleyes:
Bksmithca
2nd Jul 2021, 22:47
If it was the transmission there wouldn't be tread marks on the tarmac.
Used to have trouble pushing back 747's at Kai Tak. The problem was the slopes built into the ramp area presumably for drainage in tropical downpours and built long before pushbacks were required. A 747 rolled back about 15-20 feet to the low point before the main gear ran onto the upward slope to the crown of the taxiway which required some serious grunt from the tug and a driver who kept the tow bar dead straight until the main gear neared the crest of the taxiway. On a wet ramp slick with oily droppings it was a real problem and there were many incidents. It wasn't a tug power problem it was a lack of traction. I had a NWA 747 jackknife the tug and tow bar one morning after starting all 4 engines at the gate. No damage to the aircraft but a damaged tow bar a big hassle getting the tow bar unhitched from the tug at 90 degrees to the tow bar.. Eventually the airport authority cleaned the areas the tugs drove on and laid down an antiskid finish. Also I think it was required that engines be started on push back not beforehand.
stilton
3rd Jul 2021, 04:47
Don’t think the baggage tug added much..
NutLoose
3rd Jul 2021, 13:37
Fewdoom
Nope, it’s the tyres, hence the dirty great black rubber tyre tracks on the ground as the tug moves forward.
tonytales
3rd Jul 2021, 23:50
It is the tires that are smoking as they slip. Remember from many moons ago difficulty in pushbacks. Problem was that B707 and DC-8 didn't have APU's. The generators on the back of the Hough tugs were finicky and the long length of the ground power cable a pain so, to avoid a pushback with no lights in the cabin they would often start one engine on the gate prior to pushback. The Hough's at LASI NY were fitted with carbide studded tires for winter. Had one of these dig some interesting cavities into the cement of the tarmac as the wheels spun. Port Authority was not amused. Easter Air Lines did powerbacks with engines in later years. Machinist Union was not happy as it eliminated need for tug and driver which of course was reason for doing it.
Was up in YYZ once in a major storm. The B747 on the gate next to us had been deiced and they tried to pushback but no hope of traction even with chains. They requested a little reverse thrust, flight crew a little too enthusiastic and the blast blew windows, bag carts, etc.
Even back in the days of Connies and DC-6 pulling a plane into the hangar with a CT-120 tug could be difficult. The hangar floors are smooth, not like the tarmac or ramp outside. Even a wet floor with a little dripped oil could defeat it. Have had whole crew of mechanics get on the tug for weight and Zorball sawdust liberally spread.
Dave Gittins
4th Jul 2021, 14:51
The vehicles on the back of stand road are doing nothing wrong as there is a guy positioned out there to protect the pushback by stopping the traffic (there is probably another out of shot to the cameras right) when it gets far enough back. There is nobody on the headset to the flightdeck so I suspect this is a tow to reposition the aircraft and its brakes haven’t fully released. The tug should be plenty man enough.
NutLoose
'Track', singular. A sign of not having the tug differential locks (if so equipped) properly engaged. As anyone who has driven a proper 4x4 knows, open differentials end up giving you 'one wheel drive'. With the other three wheels producing little if any force.
Gipsy Queen
3rd Aug 2021, 22:34
I thought that the larger, more sophisticated tugs had both cross and inter-axle locks.
EEngr
14th Aug 2021, 00:54
Automatically or manually engaged?
Gipsy Queen
15th Aug 2021, 21:28
I have no idea but it shouldn't make any difference.
FlexibleResponse
19th Aug 2021, 09:11
The update comment blames glycol contamination...
From Youtube:
https://youtu.be/UzC9K1x9z1U
https://youtu.be/QqqAZKCStF8
Stephan Segraves (https://www.youtube.com/channel/UCZi0ZUOp-uoOWKsv-U4Nxgw)
259 subscribersThis United 777 was set to leave Chicago O'Hare for Honolulu when it hit a small snag.... Being too heavy for the tug. And then being too heavy for the second tug. If you want to see how this ends: https://youtu.be/QqqAZKCStF8 (https://www.youtube.com/watch?v=QqqAZKCStF8&t=0s)
[UPDATE] Apparently a lot of this has to do with glycol being on the ground and not with the weight of the plane. It still strikes me as odd that the ground crew tried to use a second tug to push the plane back.