Airbus Drivers: Single-Engine Taxi 'n APUs

[Autothrust Blue]

Huffer cart, deicing, cross bleed start, GETTING ANY EICAS MESSAGE; all require a checklist or QRH.

Ugh, although de icing and cart starts and any EICAS not associated with the configuration = same.

 

[Roger Roger]

I'd be willing to wager the fuel burn data is overall data and I would not argue that it shows less fuel burn. As I said, single engine taxi has it's appropriate uses. Single engine taxi on a one hour taxi out at JFK will certainly save fuel, but single engine taxi out on a twelve minute taxi out at SLC saving fuel is highly suspect. The pilots, in my experience, are using significantly higher than normal thrust settings for break away and after each 90 degree taxi turn. That uses more fuel than two engines running at idle or just above idle. I would say there is a time cut-off somewhere in the 15-20 minute range below which single engine taxi burns more fuel. Further, proper engine warm-up prior to takeoff reduces engine wear, just as proper engine cool down prior to shutdown reduces engine wear.


Typhoonpilot

That doesn't jive with my understanding of turbine engines. Typically they are most fuel efficient at max thrust, which suggest to me that say you need 30% thrust of one engine to break away you'd be more efficient with that than 15% on two engines. Thought I doubt you'd ever need 30% thrust to break away.

 

[derg]

I get it Derg, I get it.

Ahh the late 90's.

"Bill Clinton walks into a bar…"

"I think I've heard this one already… just this morning… told by you… in the hotel van"

 

[Cptnchia]

Huffer cart, deicing, cross bleed start, GETTING ANY EICAS MESSAGE; all require a checklist or QRH.

There is no written procedure for a huffer cart start on the MD88. Just plug it up, check your duct pressure and carry on. There is one for a bottle start, but when was the last time anyone say one of those?

 

[derg]

There is no written procedure for a huffer cart start on the MD88. Just plug it up, check your duct pressure and carry on. There is one for a bottle start, but when was the last time anyone say one of those?

There I was.

Em deeee eighty eight.

Sittin' SAC high alert.

The Russians had just struck the Fulda Gap when word came down that they needed some twenty mike-mike laid down a mountain pass.

…but muh APU was MEL'd.

 

[derg]

(An excerpt from the upcoming "Bored Airline Pilot Fantasies Over Fly-Over Country")

 

[derg]

…and if you hear someone key'ing the mic and it's an Airbus trailing you on the approach, he's just dreaming about shooting you.

 

[scooter2525]

Are you telling me that 1-1=0? And having 0 Gens is bad?

Meh. I can count with one finger how many GEN failures I've had in 8 years of 121 flying.

Plus, you're on the ground. And your brakes still work.

Hey hey! Don't shoot the messenger...

 

[Toobdrvr]

Do you single engine taxi?

And if you do, do you have the APU on or off?

1. If it's overwhelmingly advantageous to do so.

2. Many things to consider:
Taxi Time: anything less than 20 min? Prefer APU.
Cabin Temp: Really hot or cold outside? Prefer APU.
FO workload.
Something about NWS...

Either way's not a big deal to me. Any doubt? We'll start 2...

 

[Toobdrvr]

…and if you hear someone key'ing the mic and it's an Airbus trailing you on the approach, he's just dreaming about shooting you.

"PEW, PEW, PEW!"

 

[derg]

I generally tell my first officers that we need at least one to taxi, but start #2 when you think it's appropriate. "Do not get task saturated so if you want to start them both, start them both".

 

[derg]

"PEW, PEW, PEW!"

Generally on a tightly vectored DCA River Visual 19, am I right?

 

[Cptnchia]

…and if you hear someone key'ing the mic and it's an Airbus trailing you on the approach, he's just dreaming about shooting you.

Was that you who responded, "Tally Ho" when asked if they had the traffic or airport in sight the other day?

 

[Baronman]

Haven't read all the previous posts but at BlueJet:

Single engine taxi is pretty common at JFK with a long lineup for departure. APU stays on and is used for air conditioning and #2 start.

Recently we got the memo that APU must be on for SE taxi (re Fire system), so that changed the SE taxi on arrival procedure a bit. SE taxi coming in is rarer just because taxi times tend to be shorter, especially landing 31R at JFK.

 

[mastermags]

That doesn't jive with my understanding of turbine engines. Typically they are most fuel efficient at max thrust, which suggest to me that say you need 30% thrust of one engine to break away you'd be more efficient with that than 15% on two engines. Thought I doubt you'd ever need 30% thrust to break away.

Efficiency on the ground is as simple as PPH, as in 'we want to burn as little as possible before takeoff.'

 

[Roger Roger]

Efficiency on the ground is as simple as PPH, as in 'we want to burn as little as possible before takeoff.'

Right, and what I know about turbines says that likely the way to do that is to run only one engine as much as possible.

 

[ctab5060X]

I'd be willing to wager the fuel burn data is overall data and I would not argue that it shows less fuel burn. As I said, single engine taxi has it's appropriate uses. Single engine taxi on a one hour taxi out at JFK will certainly save fuel, but single engine taxi out on a twelve minute taxi out at SLC saving fuel is highly suspect. The pilots, in my experience, are using significantly higher than normal thrust settings for break away and after each 90 degree taxi turn. That uses more fuel than two engines running at idle or just above idle. I would say there is a time cut-off somewhere in the 15-20 minute range below which single engine taxi burns more fuel. Further, proper engine warm-up prior to takeoff reduces engine wear, just as proper engine cool down prior to shutdown reduces engine wear.


Typhoonpilot

We are encouraged to single engine taxi any time taxi times exceed 5 minutes. Crazy, I know, but we also don't get any grief if we start both engines. That being said, the majority of the time if I go out on two in a hub environment, I will start one, clear the gate/alley, then start the second engine.

I have seen our data regarding fuel savings from single engine taxi procedures. While it might not be much per flight, across the entire airline, the savings are enormous.

 

[ctab5060X]

I generally tell my first officers that we need at least one to taxi, but start #2 when you think it's appropriate. "Do not get task saturated so if you want to start them both, start them both".

I like that.

Might steal it from you!

 

[Autothrust Blue]

There is no written procedure for a huffer cart start on the MD88. Just plug it up, check your duct pressure and carry on. There is one for a bottle start, but when was the last time anyone say one of those?

I'm pretty sure the cart start procedure is something like - pack switchlights push out, hook up cart, check duct pressure, start it up, disconnect those things, pack switchlights push in - but I still read it from the book.

 

[derg]

Was that you who responded, "Tally Ho" when asked if they had the traffic or airport in sight the other day?

Ha! Negatron.

I know the controllers hate it but half the time when I actually spot the traffic, I mention it.