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...Single Engine Taxi...  
User currently offlineBoeing727 From United States of America, joined May 1999, 950 posts, RR: 0
Posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9592 times:

I fly in and out of IAH every time I go to work and have always wondered why none of the international airlines (Lufthansa, KLM, British Airways or Emirates) taxi single engine (B777) or dual engine (B747)...??? There must be a reason, especially with the Europeans...???

Boeing727

31 replies: All unread, showing first 25:
 
User currently offlineAS739X From United States of America, joined Apr 2003, 5997 posts, RR: 24
Reply 1, posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9579 times:

Very tough on the nose gear


ASSFO



"Some pilots avoid storm cells and some play connect the dots!"
User currently offlineLASOctoberB6 From Japan, joined Nov 2006, 2380 posts, RR: 1
Reply 2, posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9557 times:



Quoting AS739X (Reply 1):
Very tough on the nose gear

Is it really? Why so?



[NOT IN SERVICE] {WEStJet}
User currently offlineSFO2SVO From United States of America, joined Jan 2004, 398 posts, RR: 0
Reply 3, posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9533 times:



Quoting AS739X (Reply 1):
Very tough on the nose gear

I thought that was the reason Virgin America discontinued experiments with towing 747s all the way to runway - not sure how it applies to single engine taxi.
A pure guess - they want to make sure both/all 4 engines start successfully while still at the gate.



318-19-20-21 332 343 717 727 737-234578 743-4 752 763 772 D9/10 M11/8x/90 F70 RJ85 ATR72 SF340 E120 TU34/54 IL18/62/86/9
User currently offlinePITrules From United States of America, joined Jun 2000, 3033 posts, RR: 4
Reply 4, posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9532 times:

Widebody aircraft at heavy weights being taxied with a single engine require a good bit of thrust to get rolling and to make turns into the operating engine. This causes a yawing force (the airplane wants to turn away from the operating engine), which can only be counteracted by the nose wheel.

In addition, the heavier the aircraft, the more thrust required to start rolling. Jet blast might become a factor.

Some large aircraft have a limitation prohibiting single engine taxi at heavy weights.



FLYi
User currently offlineLuisca From , joined Dec 1969, posts, RR:
Reply 5, posted (5 years 9 months 1 week 5 days 16 hours ago) and read 9491 times:

I personally experienced a 3 hour delay at ATL on DL once because engine 1 started perfectly, we taxied and then they could not get engine 2 started on a 757. Now we were boxed in in a way that made it difficult to get back to the gate and we also held back all aircraft behind us for a good 45 minutes.

But from an environmental point of view I agree with 1 or 2 engine taxis. It felt like such a waste once at LHR being stuck waiting for a gate for 30 minutes with all 4 engines on a 747 idling, I don't think it would be a problem at that point to shut off 2, we only had about 1000 feet of taxiing left.


User currently offlineNZ1 From New Zealand, joined May 2004, 2238 posts, RR: 26
Reply 6, posted (5 years 9 months 1 week 5 days 14 hours ago) and read 9341 times:
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FORUM MODERATOR

NZ have started shutting 1 or 2 engines down on landing, and taxiing in to the terminal. Its not done before takeoff in case there is an engine fault. Wouldn't look good if you had just started up prior to lining up when you found there was a problem.


NZ1


User currently offlineDocLightning From United States of America, joined Nov 2005, 18687 posts, RR: 58
Reply 7, posted (5 years 9 months 1 week 5 days 13 hours ago) and read 9279 times:

I just flew on VX and we taxied about halfway to the runway before the captain turned on the #2 engine.

User currently offlineDL Widget Head From United States of America, joined Apr 2000, 2071 posts, RR: 5
Reply 8, posted (5 years 9 months 1 week 5 days 13 hours ago) and read 9264 times:



Quoting AS739X (Reply 1):
Very tough on the nose gear



Quoting PITrules (Reply 4):
Widebody aircraft at heavy weights being taxied with a single engine require a good bit of thrust to get rolling and to make turns into the operating engine. This causes a yawing force (the airplane wants to turn away from the operating engine), which can only be counteracted by the nose wheel.

Rubbish.

DL has been using the single engine taxi procedure for many, many years. After millions of aircraft movements, no problems have resulted by this procedure and no undue stress has ensued on the nose gear principally because of a wonderful little invention called a steering wheel. Perhaps the Europeans will soon adopt this procedure on their twins owing to oils upward mobility.


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2254 posts, RR: 16
Reply 9, posted (5 years 9 months 1 week 5 days 9 hours ago) and read 9134 times:

We've started using a 2-eng taxi (MD-11) both in and out but we shutdown #2 so there's no assymetrical loads.

User currently offlineAirbuster From Netherlands, joined Mar 2007, 423 posts, RR: 0
Reply 10, posted (5 years 9 months 1 week 5 days 5 hours ago) and read 9089 times:

KLM's policy AFAIK is to shut down an engine after landing, this is however SCD.


FLY FOKKER JET LINE!
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 11, posted (5 years 9 months 1 week 5 days 3 hours ago) and read 9057 times:



Quoting Airbuster (Reply 10):

KLM's policy AFAIK is to shut down an engine after landing, this is however SCD.

What about twins if there is a turn on the side of the inboard engine enroute to the gate.
regds
MEL



Think of the brighter side!
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 12, posted (5 years 9 months 1 week 4 days 20 hours ago) and read 8981 times:



Quoting DL Widget Head (Reply 8):
DL has been using the single engine taxi procedure for many, many years. After millions of aircraft movements, no problems have resulted by this procedure

Few problems...not "no problems."

Tom.


User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 13, posted (5 years 9 months 1 week 4 days 20 hours ago) and read 8977 times:



Quoting PITrules (Reply 4):
In addition, the heavier the aircraft, the more thrust required to start rolling. Jet blast might become a factor.

It does. On the 74 we almost always taxi out on all 4 due to the high breakaway thrust required. It can be quite destructive, as Top Gear and Mythbusters have shown. We also have a fuel sampling requirement to satisfy before takeoff. After landing however, we can almost always taxi comfortably on 3, and often on 2, after a cool down period.



Proud OOTSK member
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2254 posts, RR: 16
Reply 14, posted (5 years 9 months 1 week 4 days 18 hours ago) and read 8961 times:



Quoting Lowrider (Reply 13):
On the 74 we almost always taxi out on all 4 due to the high breakaway thrust required.

Just the other day I started all 3, MD-11, because of a heavy weight and congested ramp but once on the long way to the runway I shutdown #2, taxied 12 min to the runway and restarted #2.


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5638 posts, RR: 11
Reply 15, posted (5 years 9 months 1 week 3 days 9 hours ago) and read 8836 times:

It is mechanically complex to taxi a 747 on two engines.
First off, it must be the outboard engines that stay running- they do the brakes... kinda important.
Secondly, if shut down both 2 and 3, then you must run the ADP to provide more hydraulic power.
JAL will often taxi with #3 shutdown after landing, but will only shutdown both #2 and 3 if they expect a real traffic jam on the way to the gate.

As far as other carriers, I can't speculate.


User currently offlineVTBDflyer From Thailand, joined Aug 2006, 374 posts, RR: 0
Reply 16, posted (5 years 9 months 1 week 3 days 9 hours ago) and read 8832 times:



Quoting AA737-823 (Reply 15):
It is mechanically complex to taxi a 747 on two engines.
First off, it must be the outboard engines that stay running- they do the brakes... kinda important.
Secondly, if shut down both 2 and 3, then you must run the ADP to provide more hydraulic power.
JAL will often taxi with #3 shutdown after landing, but will only shutdown both #2 and 3 if they expect a real traffic jam on the way to the gate.

As far as other carriers, I can't speculate.

On my TG flight the other day (TR coming soon), we shut down the #3 engine (747-400) on taxi in. It was just a quick taxi and it was shut down about a minute after landing and runway turn off.

VTBD



Fly Thai
User currently offlineCX flyboy From Hong Kong, joined Dec 1999, 6533 posts, RR: 55
Reply 17, posted (5 years 9 months 1 week 3 days 8 hours ago) and read 8822 times:

On the 777 on a single engine only a little bit of tiller is required to keep straight....no more than you would be applying on a day where there is a 20kt wind trying to blow your tail into wind anyway. It is no big deal at all, but having said that it is not something we do (Although our SOPs allow it).

User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 18, posted (5 years 9 months 1 week 3 days 1 hour ago) and read 8764 times:



Quoting AA737-823 (Reply 15):
First off, it must be the outboard engines that stay running- they do the brakes... kinda important.
Secondly, if shut down both 2 and 3, then you must run the ADP to provide more hydraulic power.

That is how we do it. Although the only reason to keep #2 hydraulics going is so you have reserve braking. The on ground demands on #2 and #3 are so low there is no issue using the ADP. With less idle thrust at lighter weights, we are better able to control the taxi speed with the throttles, which results in lower brake temps, always a concern with the steel binders.



Proud OOTSK member
User currently offlineA342 From Germany, joined Jul 2005, 4675 posts, RR: 3
Reply 19, posted (5 years 9 months 1 week 3 days ago) and read 8748 times:



Quoting CosmicCruiser (Reply 9):
We've started using a 2-eng taxi (MD-11) both in and out but we shutdown #2 so there's no assymetrical loads.

Can you do a taxi on #2 alone? Being placed that high, jet blast shouldn't be that much of an issue (at least that's what I assume), and there's no asymetrical thrust.



Exceptions confirm the rule.
User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2254 posts, RR: 16
Reply 20, posted (5 years 9 months 1 week 2 days 23 hours ago) and read 8732 times:



Quoting A342 (Reply 19):
Can you do a taxi on #2 alone? Being placed that high, jet blast shouldn't be that much of an issue (at least that's what I assume

We all practiced it in the sim at various weights and it isn't a problem unless you're heavy and in a congested ramp. We always stay below 40% N1 for norm ops.
Believe it or not the No.2 eng has the biggest jet blast footprint because it's actually tilted up in front so does present a real problem for jet blast.
here's a quote from the CFM:

The #1 and #3 engines are subject to FOD ingestion
and create a jet blast hazard at power settings greater
than 40% N1.
The #2 engine subjects the area to a longer jet blast
damage footprint at power settings greater than 40%
N1.


User currently offlineTWAL1011727 From United States of America, joined Mar 2006, 619 posts, RR: 0
Reply 21, posted (5 years 9 months 1 week 22 hours ago) and read 8596 times:



Quoting NZ1 (Reply 6):
Wouldn't look good if you had just started up prior to lining up when you found there was a problem.

Take the very good with the rarely occasional bad and it adds up.

Quoting Airbuster (Reply 10):
this is however SCD

TWA also had "SCD"....a long time ago I asked my dad what this was and he said it was the
most important acronym in the flight manual.

SCD - Subject Captains Discretion

KD


User currently offlineA342 From Germany, joined Jul 2005, 4675 posts, RR: 3
Reply 22, posted (5 years 9 months 1 week 4 hours ago) and read 8517 times:



Quoting TWAL1011727 (Reply 21):
TWA also had "SCD"....a long time ago I asked my dad what this was and he said it was the
most important acronym in the flight manual.

SCD - Subject Captains Discretion

Hogwash. It means Side Cargo Door, of course.  Wink



Exceptions confirm the rule.
User currently offlineJAGflyer From Canada, joined Aug 2004, 3460 posts, RR: 4
Reply 23, posted (5 years 9 months 6 days 5 hours ago) and read 8442 times:

I regularly see Dash 8s using only 1 prop. Sometimes the other one is spinning slowly or not at all.


Support the beer and soda can industry, recycle old airplanes!
User currently offline777WT From United States of America, joined Jan 2005, 874 posts, RR: 1
Reply 24, posted (5 years 9 months 6 days 4 hours ago) and read 8415 times:



Quoting Boeing727 (Thread starter):
why none of the international airlines (Lufthansa, KLM, British Airways or Emirates) taxi single engine (B777)

Not approved nor recomended by Boeing due to the way the hyd system is set up with the brakes on the 777.


25 EssentialPowr : The nose gear is certainly robust enough on an airliner for single engine or asymetrice taxis, as thousands are done every day. Nose gear tires do sh
26 LimaNiner : I wonder if it wouldn't make sense to have a "double-wide" taxiway/"staging area", where planes taxi from the gate to the staging area, then shut down
27 CosmicCruiser : With the exception of your "double wide" taxiways that for the most part happens anyway. If you can't just stay at the gate, as we do, you push, taxi
28 HercPPMX : It could be possible that its taxing on one engine and the other engine is simply "windmilling"
29 Hypersonic : Given that this is a standard practice? Would you 'alternate' which engine you shut down, so as to ensure an even number of running hours overall? I'
30 Theginge : BA on their A320's shut down one engine on taxi in and also on the 747-400 normally shut down the number 3 after landing. Not sure about the rest of t
31 Airbuster : The #2 engine on the MD11 is slightly angled with the rear downwards and thus the jet blast will also be angled downwards. Actually increasing the ch
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