B737 SETO - Single Engine Taxi Out
 

Is the B737 NG/MAX approved for single engine taxi out? I am aware that most operators of the 737 do single engine taxi in.
I see a lot of operators do this supplementary procedure on the Airbus but it's not often heard of when it comes to the Boeing.

Can somebody please share the procedure for it as I have tried to find it online but only a few Youtube videos come up.

And extra bonus question, if you do a single engine taxi out, what are some extra considerations?
1. Engine warm up time?
2. Do you need to configure the fuel panel to prevent an imbalance (especially taxiing at large airports like MAD, CDG and AMS)?

Regarding the first question I have no idea about the 737 :8
Regarding the bonus question: on the Airbus 2 engines FBW fleets the warm-up time is pretty much dependent upon the type of engine and its thermal state, i.e. how long it has been shutoff for. You may or may not have a few minutes of warm-up time (again engine type related). For (very!) long taxi times fuel imbalance could become an issue and you must keep an eye on it.

Unrelated but when I used to be a flight instructor, I had a student who asked if we do single engine taxi in a Cessna 150... erm... yeah.

I’m not sure if it comes from Boeing specifically, but we have single engine taxi out and in approved for our NGs and Maxes. Single engine taxi out is not used all that frequently though where I work. When you factor the time to start, reconfigure, run the checklist, and bring the engine up to temp, it’s often not worth it. Also, the additional thrust needed for breakaway when single engine can cause issues in a crowded laneway, so I often don’t do it to prevent blasting the apron with FOD (although this isn’t really as big a deal on a Max compared to the NG).

We have a supplementary procedure in our AOM, the highlights of which are duplicated in the QRH Ops Info Section for day-of use. I’m not going to share a screen image from my company docs, but in short:

• Start #2 as normal and keep the APU running.
• Generator #2 is brought online, APU continues to supply power to the left AC buses.
• Packs to Auto, ISOL Valve closed, #1 bleed off, APU bleed on, #2 bleed on.
• Complete the after start checklist with responses applicable to single engine taxi.
• When ready to start the #1 engine, turn the #1 pack off and complete a normal engine start.
• reconfigure the electrical and air conditioning systems per normal procedures once the engine is started. Complete the after start checklist again, followed immediately by the before takeoff checklist to the line.

As for your specific questions.

1. The NG requires a 2 minute warm-up, while the Max requires 3 minutes.
3. Fuel balancing is an “as needed” condition in the checklist.

If you're considering SETO on the 737 NG, think about how many warning systems will activate before cabin altitude reaches 10,000 feet in case of a misconfigured air conditioning panel, and prevent you from an inadvertant unpressurised flight, and then think again whether the cost savings are worth it.

Thank you for taking the time to write this.
My operator does not approve SETO on any of the fleet (Airbus and Boeing) so we don't get to do it but it's nice to be aware of the procedure. I am already aware of the Airbus procedures but Boeing was a little mysterious.

The airline pays me to fly the aircraft the way they want it so I shall. Just wanted to have some extra knowledge. It always fascinates me how different operators <operate> the same aircraft.

How many warning systems will activate before cabin altitude reaches 10,000 feet in case of a misconfigured air conditioning panel?

Zero.
That was their point I believe. Very easy on the 737 to misconfigure the packs / bleeds leading to problems during the climb. Unless you’re looking at the cabin altitude indicator , the first you’ll know you’ve messed up is the cabin altitude warning blaring as you climb through 10,000’.

Only if you don't check the pressurisation panel configuration and pressurisation indications, as you are supposed to do, once the flaps are up...

Some airlines do engine out taxi out on 737s yes, as does mine. It's not that complicated actually. Start nr 2, then packs auto, isol valve closed, leave APU on. Then to start nr1, left pack off and start. Boeing has published engine out taxi out, and engine out taxi in, in their FCOM supplementary procedures. 3 minutes warm up time is recommended for the MAX at least when they are warm, and to have reached at least a certain minimum oil temp before takeoff.

Boeing from the start did not recommend engine out taxi, they released an FOTB due to customer demand back in the day to allow operators to create SOPs based on SPs that Boeing finally published (that as far as I know require approval from local authorities). The issue is more technical related to MEL items that are not designed with engine out taxi in mind.

There are failures of certain systems during taxi that might have special consequences depending on the setup, strange particularities might happen with ie regard to autoflight, hydraulic demand by flight controls, anti-ice systems, etc... (to which I can testify after having lost nose wheel steering during an engine out taxi). It all even boils down to a simple "can't start an engine in taxi" because in many companies, the LHSP is controlling the fuel control, but he is also the guy performing the taxi. So ie it would become a mandatory "parking brake set" to start an engine.

In short: you need extra training and even then... expect the unexpected (standard Boeing 737)

I wouldn't be happy with S/E taxi out.
1/ The side load on the nose wheel assembly, would not do the fuselage any good in the long run. Also a slippery surface and side load on the nose wheel, could cause problems
2/ Taxing out, the crew should be concentrating on the job in hand. Not playing around starting an engine that should be running before taxi..
3/ Possible shock warming.
Look after an aircraft/engine, it my help look after you.
4/ On an engine start, both should be monitoring the start. That cannot be done during taxy. When taxing BOTH pairs of eyes should.be "outside the cockpit" as much as possible.

Of course! However that could be said of any accident that involves human error with systems mis-configured.

If you're mitigating a risk versus mitigating a tiny amount of fuel burn, I know what my decision would be.

Same goes for SE taxi in - there are very few airports that my company operate into where it would achieve the desired fuel saving. We do a lot in the name of conservation that seems to be poorly thought out.

Real fuel savings come from well designed SIDs / STARs and efficient ATC / ground handling / gate coordination.

A tiny amount of fuel multiplied by x airplanes in the fleet multiplied by x sectors per day.
I can guarantee you that your CP office will not have the same opinion as you.

From what I know, the B737 NG/MAX can do single-engine taxi out, but it depends a lot on the airline's specific procedures and the situation. It's more common for single-engine taxi in, but some operators do it for taxi out to save fuel and reduce engine wear.

It is a very bad idea and I include single engine taxiing after landing as well. Certainly SETO both pilots should be monitoring the engine start. Also both pilots should have good SA on the ground and prioritize taxi routing and other aircraft. The fuel saved taxiing in is a smoke and mirrors exercise whereby bean counters come up with a fictitious amount of fuel saved also emphasizing their much heralded green credentials. In my last airline it went like this: start lever to cut off followed almost by a doubling of the fuel flow on the other engine. If you come to a halt, always possible, the amount of thrust to get going would be tripled. Some captains in order to ‘tick the box’ would ask for the start lever to cut off a few meters before arriving on stand. This action would be collated and added to those who did it ‘properly’ and at some stage later a ‘fuel saving manager’ would come up with imaginative figures and triumphant carbon saving the planet credentials. SETO, not for me, too risky on many levels.

Can you provide a reference to any incident where SETO was a factor?
CP office will tell you SETO has been happening for decades all over the planet.
"Too risky" means nothing.
Doubling of fuel flow on one engine when one is shutdown? I'm dying to ask what type you fly.

Yup, love it when pprune gets personal from all the experts out there. Firstly SETO has not been around for many years. Most CPs (sic) know the square root of foxtrot alpha. The fact that there has not been an incident does not mean that the procedure has been robustly risk assessed. I am not going down the road of saying which aircraft I fly or have flown as we are now in the standard willy waving pprune scene whereby x has eg 28,000 and ergo they are the fount of all wisdom. I have flown a mixture of Boeings including 737 and 747 ( including instructor / examiner) also Airbus A340 and instructor on A380. I currently work as an instructor for a well known manufacturer. Hope that helps. I don’t pretend to be the definitive expert but I have been around.

B737 after take-off checklist:
Bleeds - ON
Packs - Auto
...

Are we normalizing the "forgetting" of normal checklists here?

@Olster all your remarks boil down to correct training and assessing the situation. SETO/SETI is not mandatory, it's an option if the situation allows. All the rest boils down to your pilot attitude, not the procedure in itself. The procedure has a strong right to exist but needs proper training of pilots.

Fortunately some of us work for airlines, where chief pilots take the downsides of SETO seriously, and steer cleer of it for those reasons.

What also needs to be taken into account is average taxi length - it's rare to taxi out for more than 15 minutes where I fly, making any potential gains quite miniscule, compared to all the risks. Now, if you fly in USA with the 3 hour conga lines instead of A-CDM... then it makes much more sense.

And that is why at the company I work for, the decision to conduct or not conduct SETO is left to the pilots in the moment. If a CP looks at their operation and identifies that, due to average taxi time, there is more risk than reward, then that CP should not implement the procedure. However, a CP working at an airline that does operate to airports with average taxi times that exceed 25 to 30 minutes with aircraft sitting in a line may come to a different decision. I've spent the better part of 20 years working for airlines where SETO was a well-established practice - turboprops to jets. At every company there were robust rules of when and when not to conduct SETO. Every year the ops office would examine the occurrence record for the fleet, and in some cases SETO was identified as a large enough contributing factor over the year to warrant the publication of additional rules. For example, when a new runway was added at my base airport, it became obvious to everyone at every airline that utilizes the airport that there was a hot spot at the intersection of four taxiways as the rate of taxiway incursions skyrocketed. A part of that was the poor design and signage of the intersection, but another part was that is where many pilots reported they were either just starting or just finishing an engine start. By this point they had been taxiing for about 10 minutes with another 5 minutes to go, so not unreasonable for using SETO. My airline started by publishing a guideline that if conducting SETO, the engine had to be fully started and checklist complete by that intersection or had to be started after passing through that intersection. That seems to have done the job as the rate of taxiway incursions at that airport has dropped back to what is considered the background rate.

How many times have you done SETO with a B737?
Do you find your A380 instructor experience provides you a unique insight into B737 SETO ops?

Yet once you become chief pilot somewhere, I’m quite sure you will not abolish the practice of single engine taxi operations. The argument that the aircraft might have to come to a complete stop necessitating ‘triple fuel flow’ on the live engine to start moving again will be negated by the hundreds of other crews who are able to sensibly shut down an engine taking all variables into consideration, coasting in beautifully and effortlessly to the gate.

But you have piqued my curiosity. How does your current employer (the aircraft manufacturer) regard single engine operations? Do they agree with you? Do they discourage the practice? And do they communicate that to the pilots of their aircraft?

Penko, I am not able to answer that question. The thread dissolved into a personal and profane diatribe towards me for bizarre reasons. I completely understand differing opinions and accept the rationale for SETO in terms of fuel saving, which again personal opinion I believe is ‘risky’ for well documented reasons. As people are so interested the last 737 airline I worked for carried out SETI (including me) with many caveats. They risk assessed SETO and found it wanting. The main reason being SA on taxi was compromised and engine start is supposed to be monitored by both pilots. I am not at liberty to say what the manufacturer thinks of the procedure but a straw poll of colleagues were aligned with the view I have given. Hope that helps.

I will do it when the rate of taxiway and runway incursions stops increasing, flatlines, and then starts decreasing.
We need to have our minds on the job folks.
We are splitting our attention between more and more things as technology increases and our attention is a finite resource.
Last week I was lining up at night, we had already been cleared for takeoff when my f/o told me that new weather had become available at our destination …..where was his mind? Were we on the centerline? Were the flaps set? Had the landing traffic cleared? Was the radar painting anything on our departure track? Were the packs ON? Were the FMA’s armed? Was the trim set? Was it the correct intersection? Was it the correct runway?What was our target attitude airborne? ……There is a long list of things you could use your limited attention for just prior to takeoff. At the moment, globally, we are not doing a good job of allocating that attention. Maybe this is because of the ability to update our iPads weather function or maybe it’s a combination of lots of things but we need to regroup, pair it back, and keep it simple or we are going to have another Tenerife on our hands.

I agree with my reluctant colleagues here and even though my bosses promote it, I rarely SETO because of the many risks and less desirable factors already described in this thread. Since my company operates more 737s than any other carrier, however, I do understand management’s desire to potentially reduce fuel usage on several thousand flights per day.

I won’t say no Willy waving, then do precisely that. That was interesting.

It's up to every captain's risk management to assess whether single engine taxi out and/or in is appropriate, no right or wrong. I am no conspiracy theorist and if the fleet office says it's saving fuel I have no reason to believe otherwise.

We put SETO and SETI into the Ops manual back in 2013 and we all started to use it then. There wasn't a single incident or issue with it. It is so routine that I am genuinely amazed it is even a discussion point. Yes it has to managed properly, but so does everything.

Something to consider…
 

I wouldn’t want to leave the gate area or have the pushback tug disconnect until I knew both engines and generators were working. A bit of a palaver if, after some single engine taxi, to approach the departure end of the active runway, only to then see that the other engine or generator would not operate properly.

it’s risky enough to shut down at a remote holding point, then hope they both start up when your slot comes up.