Questions regarding an Aviation Project

[lvlann]

Hello guys, My partner and I are working on a project to reduce fuel cost through APU usage.
i have a few questions regarding that.
1) When is a good time to shut APU off
2) Is it necessary to operate APU during Takeoff?
3) What are some innovative ways one can help fuel reduction on ground?(taxi, one engine taxi, etc)

now for the third question you need this information.
The airlines we are working on are United, Delta, Southwest, Alaska, American and the plane we are working with is a Boeing 737.
The airports we are concentrating on are:

San Francisco International
San Jose International
Oakland International
San Diego International
LAX

now the question..

How long does it take for an airline given above to reach the start of a runway from their respective terminals? (For takeoff)

how long does it take for an airline given above to reach their respective terminal from the runway?(upon landing)

I know I might not get an exact time due to many uncontrollable factors, but I'd like it to be as close as it possibly can.

All your help will be greatly appreciated.

[99jolegg]

1) it depends on the airport (some are more noise sensitive than others), the location (hot locations on a turnaround with no air conditioning isn't pleasant), the aircraft and the company. On a medium sized jet in "average" temperatures we switch the APU off in the day when the ground power is in and the passengers are disembarking or at night, when all of the passengers are off. We start it either 5 minutes before departure, when all the pax are on or when it gets uncomfortably warm in the cabin.

2) Again, depends on the aircraft and the location. You can squeeze the last bits of performance out of an aircraft by operating the air conditioning via the APU so at some airports, the APU is used for landing / takeoff, such as INN but again it depends on the operator. By and large though, the APU isn't necessary for takeoff.

3) Single engine taxi arrival, single engine taxi departure, minimal use of the APU when possible and some airlines are looking at getting motors attached to the main landing gear to taxi without engines running.

Not based in America so can't answer the last part, but as you recognise, taxiing around international airports in terms of time can be hit and miss depending on how busy it is.

[sb_sfo]

Since the terminals are spread out and the runways generally used are at 90 degrees to each other, you will get wide differences in taxi times. For example, a UA or DL domestic will land on 28L, roll out on Tango or Echo, and be at the terminal in about 3 minutes. That same aircraft, departing, will have to taxi to 1L, and it will take 15-20 minutes, depending on traffic. DL is nearer the center of the airport. AS in off to the other end, so arrival will take longer, taxi out is shorter.

My outfit uses 20 minutes as a taxi time for departure from the International Terminal "A" side, so if we are using the 28s, that's about right. If we use the 1s, 5-7 minutes. Typical arrival taxi off the 28s is about 8 minutes.

However, with SFO, you have to account for afternoon winds. At about 1400 daily they pick up, and if they go to 20kts, we lose Runways 1. At that point, everybody uses the 28s, and you can easily be #12 for takeoff. With the landing traffic as well, 30 minutes is easy.

Most international carriers start all engines on pushback. Many will shut down one or more on arrival. I've seen Air France taxi a 747 on one engine, and they don't like to stop! Not recommended. On the other hand, JetBlue will taxi in on 2 engines, no APU, and keep both running at the gate until the jetway is set, and the GPU hooked up, which can take 3-5 minutes. Burns extra fuel, but saves on APU running? :ugh:

In my outfit, we encourage the crews to shut down one engine on a 777 on taxi in, though few crews do it, and we hook up GPU and AC within 3-4 minutes after arrival. Start APU about 10 minutes prior to departure.

Your mileage may vary...