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arnobg

One engine taxi?

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Done a lot of flying the last couple weeks however, none was on a 737 NG so I won't know if this procedure applies? Is it not a common practice to taxi on one engine during long taxi in the 737 aand startup once close to departure, or is this only a procedure with other aircraft? I would think it would save quite a bit of fuel at airports like ORD and ATL during long taxi and lines.

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Well, I guess it comes down to Airline SOP...... but usually yes - is common practice, at least with some Airlines I've flown with......

 

regards

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Is this procedure able to be used with fs2crew properly? Or am I going to have issues during checklists if only one engine start is initiated

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Is this procedure able to be used with fs2crew properly? Or am I going to have issues during checklists if only one engine start is initiated

 

Don't know if fs2crew supports it, but more importantly FSX doesn't really support it. Even with full opposite rudder you likely won't be able to taxi straight, and forget about turning against the running engine.

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I wouldn't try... that asymmetrical thrust is difficult if you're not used to it.  Some aircraft will refuse to turn into the live engine with any thrust at all.  Even the prop twin I fly won't do it, one has to get some momentum going before the turn and then pull power back and coast through the turn... not recommended for normal procedures.  I is easier to fly on one engine than it is to taxi LOL.

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You can use FS2crew, but you'll have to start the second engine on your own. Also I've done one engine taxis befor if I know the taxi will take a while, also I don't find it hard to taxi, except when you need to turn in whatever direction the running engine is on, So if you have the number one engine running, it will be slightly harder to turn left and vice versa. I also tend to shut off one engine before entering the ramp area, Typically the number two engine seeming how the groundcrew connects the GPU on that side. I've also Heard that Southwest has recently gone to 1 engine and taxis, but that is unconfirmed, and I know United uses one engine taxis in there A320 and 319s sometimes, i've seen them having to wait about two minutes before taking off at the end of the runway at PDX (not sure if they use that same procedure for the 737s.

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Is it due to unrealistic physics in FSX or will a cfg edit fix the uncontrollable turning

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We are authorized to taxi single engine but hardly anybody does.  It takes a lot of power to get the airplane moving on one engine and the jet blast can cause problems in the ramp area.  When we know we will have a long taxi and will want to shut one down it's normal to start both engines for taxi and then shut one down once we have gotten away from the gate area.

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I did them a bit when SFO had 1L and 1R under construction, but I haven't done them in a while. You gain a bit of fuel, but the FO goes out of the loop for a while to do the checklist. If it was done more often, I think we could do it safely, but it's done infrequently enough that it's not easily accomplished.

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I wouldn't think the fuel savings would offset the engine cycle costs.... each cycle cost money, right?

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You're not getting more cycles, are you? You're just running the APU a bit longer. We don't pay by the cycles on the APU anymore, anyway. It's just gallons of fuel now.

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Is it due to unrealistic physics in FSX or will a cfg edit fix the uncontrollable turning

 

if you have FSUIPC installed you could try their dynamicfriction.lua fix....... you will find it in your FSUIPC Documents folder under example LUA plugins.....

 

regards

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Would you really save fuel? Because you having to use more power to get rolling and maintain speed (but that might be fsx) to The point where taxting with one engine would equal the same amount of thrust as texting with two engines, So would you really save that much fuel?

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Would you really save fuel? Because you having to use more power to get rolling and maintain speed (but that might be fsx) to The point where taxting with one engine would equal the same amount of thrust as texting with two engines, So would you really save that much fuel?

I don't know how much it would save, but enough that my company provides a chart for busy airports that gives us suggested times of day to use SE taxi.

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On more than one occasion it's been the difference between departing and returning to the gate for fuel.  We don't do it often but on those days with bad delays it's beneficial.

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Thanks for all the replies and discussion. I looked into the FSUIPC fix and it seems that it would affect aircraft who's friction was already modified for FSX too due to FSX's unrealistic friction. That would make things worse on some aircraft. Wish there was a solution to properly use this procedure.

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Brett, in a Brazilian company, the last Check List Revision (26/11/2014) they put a blue area called “Single Engine before taxi”, but this procedure is not authorized until this moment (this is for Taxi to TO/)... But anyway, if you have interest, follow the pic ;)

 

image.jpg

 

For taxi (after landing) it’s authorized and happen very often, follow the complete procedure after landing, start the chronometer just after put the engine idle from reverse to this procedure...

 

NP_APU.jpg

 

Tip: I should say to you that are pretty normal to taxi with one engine running after landing, but you need to care to not put too much power in the engine running (N2). If you take it easy and gentle you will have a peaceful taxi turning to both sides w/o problem...

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I remember discussions sometime back regarding Single Engine Taxi and talk about higher thrust required for breakaway and slightly higher thrust requirements for single over two engine taxi. Specifically higher thrust levels posed a potential hazard to ground personnel, airport structures and equipment, and other aircraft from blowing FOD.

 

All of that might either be old school or platform dependent as I can tell you that SOP for Delta Airlines MD-88s (I have no idea about other types) is single engine taxi, and they have a delayed start checklist for the non-running engine. Some airlines also do this with the Dash 8 (Turbo Prop).

 

I agree with Dan, I would think the fuel savings under most circumstances would likely be negligible, so the reason might be aggregate maintenance costs (the savings would add up during the course of the year of operations, especially over many different aircraft), but this is pure speculation on my part.

 

Excellent topic. A search of the AVSIM forums found several past topics on this very subject, though they didn't appear to contain much different information than what was covered here.

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Taxiing on less than all available engines is becoming an increasing common procedure, certainly here in the UK. It's SOP for most operators to shut down one (or even two on quads) after shutdown, and OETD (One Engine Taxi Departure) is becoming increasingly common. Certainly it's pretty much standard procedure for at least one major operator.

 

Obviously the main considerations on taxi out are warm-up times -- most engines require a certain amount of time at idle to allow temperatures to stabilise before takeoff thrust is applied -- and to a lesser extent the implications of having a problem with the engine start whilst at a remote location.

 

In terms of fuel savings, it's important to remember that whilst the savings for each individual aircraft may be negligible -- I don't know what the typical figure for a 737 would be, but I've seen 120kg for shutting down two engines on a 747 for the taxi in -- when multiplied across a fleet the savings are signficant. Even if you were only saving 30kg by taxiing out on one engine, to give an example, Southwest have 550 737s averaging 6 flights per day. That's 3300 flights per day. If each saves 30kg, that's 99,000kg of fuel saved every day across the fleet. That's nearly 3000 tonnes a month, or more than 35,000 tonnes per year.

 

Marginal gains, but they all add up when you have lots of aircraft flying lots of sectors!

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I tried it in my sim with the pmdg NGX tonight and while it was kind of a pain it is possible in FSX. It requires more "paying attention" to keep it on the center line which wasn't very fun at all. It's too bad really, because I think it would be an awesome procedure to simulate to change things up and make it more interesting and different flight to flight.

 

The whole reason this came to mind is because on my recent flights with Delta this week every flight but once (4 legs) did a single engine taxi, starting the second close to departure during taxi.

 

ATL-HOU B712 single engine taxi on departure

HOU-ATL B712 single engine taxi on departure

ATL-TRI CRJ2 single engine taxi on departure

 

While none were 737's listed above. I have seen Southwest do it when I worked at JAX, and the Piedmont Dash-8's do it 99% of the time even on short taxi's.

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Boeing recommends against single engine taxi.

 

Wow!

 

Do you have a reference for such a sweeping generalisation or is this another of those 'Flight Sim 101'isms' that do the rounds?

 

The post just before yours clearly shows some reference material from a RW operator that has been produced with the help of Mr Boeing himself.

 

If your still unsure I'll give you some more clues ...

 

Go & take a peek into the PMDG_NGX_FCTM yep the one that was FREE with the product ...

 

page 98 (Engine Out Taxi) & page 401 (Engine Out Taxi)

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From the 737NG FCTM:

 

"Taxi - One Engine

Because of additional operational procedural requirements and crew workload, taxiing out for flight with an engine shut down is not recommended. High bypass engines require warm up prior to applying takeoff thrust and cool down prior to shutting down. If the engine has been shut down for several hours, it is desirable to operate at as low a thrust setting as practical for several minutes prior to takeoff.

If an engine is shutdown during taxi in after flight, the crew must be aware of systems requirements, (hydraulics, brakes, electrical). The APU should be operating while taxiing with an engine shutdown. If possible, make minimum radius turns in a direction that puts the operating engine on the outside of the turn. In operational environments such as uphill slope, soft asphalt, high gross weights, congested ramp areas, and wet/slippery ramps and taxiways, taxi with both engines operating."

 

If you're still unsure I'll give you some more clues: "taxiing out for flight with an engine shut down is not recommended." You should really check you're right before bagging others.

 

Checking the 747 FCTM, Boeing do not recommend more than 2 engines shut down, one from each side max. All the usual check carrier SOPs etc is stated.

 

Airbus don't seem to mind across the fleet. The usual safety warnings are in place.

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Perhaps you might want to look more closely at the reference material, here are the links that I provided earlier directly quoted from the source:

 

PMDG NGX FCTM GROUND OPERATIONS 2.14 pp98

 

Engine Out Taxi

Appendix A.2.3

 

Engine Out Taxi (EOT) operations have the potential to save fuel and to reduce carbon emissions.

 

During EOT operations, the crew’s attention should be focused on taxiing the airplane. Distractions should be kept to a minimum. Boeing does not publish specific procedures for EOT operations. Each operator develops EOT policies, procedures, and flight crew familiarization materials specific to their operation and in accordance with the requirements of their regulatory authorities.

 

PMDG NGX FCTM Appendices Supplemental Information A.2.3 pp416

 

Engine Out Taxi

FCTM 2.14

 

If operator policies, procedures and flight crew familiarization materials are appropriately applied, EOT operations can be conducted safely and should be acceptable to flight crews and regulatory authorities.

 

Operator policies, procedures and flight crew familiarization materials should include, but not be limited to the following:

 

•airport layout

•taxiway composition

•taxiway slope

•foreign object damage (FOD)

•airplane system redundancy

•engine warm-up and cool down times

•fuel balancing•crew workload and heads-down time

•current weather, including temperature and wind

•current taxiway surface conditions

 

Each operator should establish Standard Operating Procedures (SOP) for EOT operations. These SOPs should provide the flight crew with clear, concise guidance for EOT operations.

 

More information on EOT operations is available in the Boeing Flight Operations Technical Bulletin titled "Engine Out Taxi". This Bulletin can be found on MyBoeingFleet.

 

 

I'd be very interested to see the reference source, edition date & page number for your source.

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Interesting how real world Ryanair FCTM disagrees with the one sent out for free with a piece of game software.

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