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Olendirk
4th Jun 2006, 06:21
Hello,

does anyone of you guys have experience in a single engine taxi operation especially on the 737ng and the airbus? are the savings big? links appreciated!

Thanks!

OD

Gold Leader
4th Jun 2006, 09:00
Hi OD

Not really... we are flying the NGs and our company does not recomend it. aslo as far as the FCTM goes it also discourages it. (Refer to BOEING 737 FCTM Rev. 5 Page 2.14)

GL

TomConard
4th Jun 2006, 11:45
Dear Olendirk,

I humbly submit my opinion...and that's all it is. I have nothing to back it up.

None of the aircraft manufacturers, that I know of, is a proponent of single-engine taxi. They, however, provide guidance and procedures only because customers ask for (demand) them. Again, this is my opinion.

Years ago, I flew for an airline that was primarily a 737 operator. Single-engine taxi was considered 'normal' for them. That is, most flights did single-engine taxi. On the 727, we taxied with the number three shut down.

Later, my company was bought out by another airline. The new SOP, initially, prohibited single-engine taxi. Unfortunately, the combined airlines created a giant operation...over 2200 flights per day, and options to save even a dollar or two per flight quickly became the focus of the bean counters.

Maybe ten years or so ago, this same company bought a bunch of the single-aisle Airbus (like 125 or so on the initial order). While the 737s remained on the property still doing single-engine taxi, the Airbus drivers were prohibited from doing single-engine taxi. Airbus said 'No'.

Again, the bean counters soon intervened. Wouldn't you know it, but Airbus soon came out with an "NTO" (no technical objection) and provided my company with a procedure for single-engine taxi. The FAA was happy, the bean counters were happy...that's pretty much all who matter in today's American aviation.

Regarding savings...if you're operating a fleet of ten or 20 planes mostly in an out of relatively non-congested airports, single-engine taxi (again, in my opinion) is not worth the trouble. But, if you're operating 2200 flights a day with many in and out of New York, Boston, Washington, Philadelphia, Atlanta, Chicago (you get the idea), where taxi times frequently run 45 minutes to an hour or more, then single-engine taxi can make the difference between profit and loss. (No kidding!)

If you save only 50 pounds of fuel (22.5 Kg) per flight...at $1 USD per gallon...that's roughly $7.50 USD saved per flight. If you run 2000 flights a day, and are able (operationally) to do single-engine taxi only 25% of the time (500 flights)...that's $3750 USD saved per day, or $1.36M per year.

Once the bean counters see figures like these, operational procedures quickly change.

Can it be done safely? Well, that's another opinion. I feel that single-engine taxi degrades safety...for a number of reasons (I won't elaborate). But, if done properly....as per your company's SOP...and with good judgement, the level of safety is still acceptable. (Again, in my opinion)

There are a number of considerations...and the list that follows is certainly not exhaustive: aircraft weight, ambient temperature, taxiway surface type, taxiway surface slope, surface winds, surface contamination, proximity to buildings, vehicles, personnel, other aircraft, etc., MEL/CDLs, estimated taxi times, engine warm-up time requirements (first flight of the day on a cold morning...or a quick turn on a hot afternoon), pushback, taxi out procedures, local airport restrictions, taxi route, current union/management relations (couldn't resist adding that one!!!)...just to name a few.

Single-engine taxi in not feasible, allowable, or advisable in many cases. If you listen to the bean counters, 90% of the flights can be done with single-engine taxi. If you listen to seasoned captains, maybe less than 50%...or less than 25% of the flights can be done under single-engine taxi. (Again, my opinon.)

That's all I have to say about that...


Tom

TOGA Descent
6th Jun 2006, 01:21
Single-engine taxi in not feasible, allowable, or advisable in many cases. If you listen to the bean counters, 90% of the flights can be done with single-engine taxi. If you listen to seasoned captains, maybe less than 50%...or less than 25% of the flights can be done under single-engine taxi. (Again, my opinon.)


Tom



The most informative post I've seen on this subject. The final paragraph sums things up perfectly.