Single Engine Taxi v's annual profits

[73qanda]

G'day,
I was wondering how much single engine taxi contributes when compared to annual profits or losses.
Question 1; How many jet sectors does the QF group do per day?
( I googled it but couldn't work it out from the different web pages I went to)
Question 2; How much would the big jets save if they averaged 2 minutes se taxi?
What I am trying to work out is if all the QF group jets averaged 2 mins se taxi per sector what would it do to an annual profit or loss?
Just curious really to see what impact it has.
Any input appreciated,
Cheers,
73qanda

[AbsoluteFokker]

Safety implications?

i.e. What's the difference between starting an engine then within seconds or minutes, going to takeoff power AND starting it, let it warm up during taxi/(runups) then taking off?

If not safety, perhaps premature maintenance/overhaul issues?

[73qanda]

I'm only interested in taxiing in single engine, not departing.
I'm with you that there are potential safety implications but that is why it is left up to the Captain to decide if it is appropriate or not.

[AbsoluteFokker]

Surely premature maintenance issues are also a significant impact to earnings too?

And that is not up to the Captain to decide (unless that "Captain" wears pies).

[Squawk7700]

I would expect that the required "warm up" time that you speak of would often be significantly less than the total time required to taxi to departure, so the second engine could be presumably cranked on the way out and still meet takeoff requirements prior to departure.

[Band a Lot]

I am surprised it is not standard practice and also not even a self start or a start warning based on warm up time of even a particular engine on given temp conditionings.


It could also be programed further on the many factors available today. What is the worst case at a busy port? wait at holding for another aircraft to land if by chance you are not "warm" or if very close an extra 10 second line up (with warning).


It would certainly same lots of fossil fuel over a year.

[73qanda]

Surely premature maintenance issues are also a significant impact to earnings too?

That is taken care of by providing guidance on how long the engine has to be at idle prior to shutting it down, ie a cool down period. It's dependant on whether reverse was used etc.

i.e. What's the difference between starting an engine then within seconds or minutes, going to takeoff power AND starting it, let it warm up during taxi/(runups) then taking off?

There is also warm up guidance prior to a take off but I am only talking about se taxi on arrival at destination anyway.

[havick]

Originally Posted by 73qanda

That is taken care of by providing guidance on how long the engine has to be at idle prior to shutting it down, ie a cool down period. It's dependant on whether reverse was used etc.
There is also warm up guidance prior to a take off but I am only talking about se taxi on arrival at destination anyway.

Usually a 1min cool down prior to single engine taxi on arrival (here in the USA anyway). Though sometimes keep both burning if it's tight turns into the gate.

[bafanguy]

SOPs for reduced-engine taxi in/out will be designed based on manufacturer's recommendations for idle times contributing to max engine health. And yes, there are important economic benefits attached...the bigger the fleet the bigger the economic benefit. Just for example, the JT8D-219 needed 2 minutes at idle prior to setting T/O power...and one minute at idle before shutdown after landing.

We even did single-engine taxi in/out on the B727 when circumstances allowed.

As Havick mentioned, there are several very practical considerations to NOT doing reduced-engine taxi. The captain will decide when/if.

Blow over a bunch of baggage carts/injure ramp workers doing reduced-engine taxi in/out and see how far you get telling the boss how much money you were trying to save the company.

[By George]

One is reminded of the Saudi 747 in KL taxiing to the gate with 1 and 4 shut down. The only problem being the Aux HYD pumps were OFF (Engineers taxiing, not pilots). Into a ditch it went, breaking the fuselage just behind the cockpit. Another one of those 'it seemed like a good idea at he time' events. It was a terrible sight seeing that lovely aeroplane sticking out of the ground like a giant arrow. Why look for trouble and make life complicated.

[73qanda]

Why look for trouble and make life complicated

That wouldn't be a bad personal mantra for an Airline pilot.

[Band a Lot]

Originally Posted by By George

One is reminded of the Saudi 747 in KL taxiing to the gate with 1 and 4 shut down. The only problem being the Aux HYD pumps were OFF (Engineers taxiing, not pilots). Into a ditch it went, breaking the fuselage just behind the cockpit. Another one of those 'it seemed like a good idea at he time' events. It was a terrible sight seeing that lovely aeroplane sticking out of the ground like a giant arrow. Why look for trouble and make life complicated.

Boy George - this from Rumours & News.

RoyHudd:

"airlines should have pilots at the forefront. Simply because they understand what the business is all about"

Problem is that most pilots have no idea of airline economics beyond costs and 'bean counting'.

Ask any one of them how to reduce costs (ok) whilst at the same time maximising revenue and you'll be met with a blank stare.

It surely ain't cost per seat ? Revenue management, what's that ?


__

Simply SOP's for pilots and engineers alike would work for single engine taxi.

P.S How many engineers have done a gear up landing?

I have seen many gear up landings, never pretty and never an engineer!

[By George]

'Band a Lot' I wasn't having a shot at Engineers, I think they are a marvellous invention. My best flying was with 'three-man crew' and I miss their presence in the cockpit.

[Band a Lot]

Cheers n Beers then - sorry got wrong impression. Accidents happen - SOP's should reduce/stop them.

[73qanda]

So, does anyone have any idea on the number of wide body sectors the QF group does per day and the number of narrow body sectors they do per day?
I reckon if I knew a ball park figure I could work out roughly what % impact se taxi has on annual profit which is what motivated me to post in the first place.
I really don't know how great, or small the impact is.
Cheers

[Shagpile]

Small deviation from the original question: for large airports with long taxi's, have aircraft ever been pushed back & towed to the holding point & started engines 2-3 minutes prior to takeoff ?

[havick]

Originally Posted by Shagpile

Small deviation from the original question: for large airports with long taxi's, have aircraft ever been pushed back & towed to the holding point & started engines 2-3 minutes prior to takeoff ?

I've seen it once where an aircraft wouldn't have been able to make their min t/o fuel for a ferry flight.

I think virgin America were looking at doing a trial with automated tugs, towing aircraft around until they needed the required engine warm up period prior to takeoff.

Rumors of Boeing or airbus new designs having some one the wheels turned by electric motors so you can self taxi on just the APU.

[DutchRoll]

Originally Posted by havick

Rumors of Boeing or airbus new designs having some one the wheels turned by electric motors so you can self taxi on just the APU.

Be interesting to see what happens the first time a big jet lands with the motors engaged, either accidentally or through a fault.

[havick]

Originally Posted by DutchRoll

Be interesting to see what happens the first time a big jet lands with the motors engaged, either accidentally or through a fault.

I agree, though think about how many hybrid cars are out on the roads these days without electric motor issues.

Wouldn't be hard for the OEM to install an interlock and relay the prevents the motors being energized until both engines see shutdown and the thrust levers at idle.

[Traffic_Is_Er_Was]

have aircraft ever been pushed back & towed to the holding point & started engines 2-3 minutes prior to takeoff

Only the first one. All the others get delayed by the tugs clogging up the taxiways returning to the aprons.

Plus, what if you have start problems? Do you want to find out close to the apron where you can return for engineering, or 100's, maybe 1000's, of metres away at a holding point, blocking access for everyone else.