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Advantage Of TO/GA Switch On Autopilot  
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Posted (9 years 1 month 3 weeks 4 days 19 hours ago) and read 14494 times:

Can a pilot answer what the advantage is of the TO/GA switch on both take off and go around? What does it do that a pilot can't do by just advancing the throttles and taking the aircraft into a climb? Is there some hidden benefit of its use?

Jules

15 replies: All unread, jump to last
 
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 1, posted (9 years 1 month 3 weeks 4 days 18 hours ago) and read 14491 times:

On the Airbus:

When the thrust levers are moved to the TOGA detent and flaps are at least position 1 and the aircraft is airborne or has been on the ground less than thirty seconds: It combines the SRS (Speed Reference System) vertical mode and the GA TRK (Go-Around Track) lateral mode of navigation for the command bars and/or autopilot.

That saves you a lot of button-pushing and knob twiddling at a time when you are apt to be rather busy. Not all missed approaches are just climb straight ahead. Some of them involve turns and intercepts and holds etc.

It also enables the thrust management system to operate the engine at any required power setting from just above an idle all the way up to Takeoff/Go-Around thrust.

For Boeing products it will do similar things but I've been away from them for a while.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineD5DBY From , joined Dec 1969, posts, RR:
Reply 2, posted (9 years 1 month 3 weeks 4 days 18 hours ago) and read 14484 times:

ive been thinking about this to..but cant you make a take-off with the AP if your AC if equipped with a TOGA function? and if you can...that I guess is nice for flight crew, to let the AP do the take-off....but im not sure the AP with TOGA function can do this....just speculation

User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 1 month 3 weeks 4 days 16 hours ago) and read 14451 times:

But I thought everything was so simple these days?!



User currently offlineJetlagged From United Kingdom, joined Jan 2005, 2577 posts, RR: 25
Reply 4, posted (9 years 1 month 3 weeks 4 days 16 hours ago) and read 14446 times:

Most modern autopilots could probably handle a takeoff, but they aren't certified for it and it can't be selected.

The importance of the TOGA buttons is to switch the autopilot/autothrottle system from approach mode to go-around mode. Yes, the pilot could manually reselect the AP pitch mode and adjust the throttles manually or change the AT mode. However if you have a go-around call just before touchdown there's not a lot of time to do all that. The TOGA button, in one selection, takes care of it all. While this is happening the crew still have to retract flaps and gear, call ATC, etc. so it's a busy time.

Even with AP disengaged TOGA will put the flight director into go-around mode to command the appropriate pitch up for the selected flap angle.

During takeoff, TOGA selects the AT to takeoff power (the flight director will already be in takeoff mode by default). It's a convenient means of selecting this mode. Back in the day, they were merely GA buttons, then FFRATS came along so a selection was needed to put the throttles in takeoff mode, and the GA button became the TOGA button.



The glass isn't half empty, or half full, it's twice as big as it needs to be.
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 5, posted (9 years 1 month 3 weeks 4 days 13 hours ago) and read 14397 times:

thanks for all the information , so is the TOGA switch used during take off a lot or is it really a Go Around function mainly?

User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
Reply 6, posted (9 years 1 month 3 weeks 4 days 11 hours ago) and read 14370 times:

In Boeings the thrust levers are advanced manually from idle and when the engines are stabilised at about 40% N1 the TOGA switch is usually selected and thrust levers would advance automatically to the selected takeoff N1/EPR.

But this procedure should vary from airline to airline.  

Cheers  Smile

[Edited 2005-10-29 03:32:02]


Boeing747 万岁!
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 1 month 4 days 18 hours ago) and read 14040 times:

Still got a few questons about this:

Quoting Mr.BA (Reply 6):
thrust levers would advance automatically to the selected takeoff N1/EPR.

1) How does it know what you want the N1/EPR to be on take off? How do you select it?

2) Will the TOGA switch automatically pitch you up when you reach take off speed or do you still have to manually pull back the stick to get the aircraft off the ground?

Thanks, J


User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
Reply 8, posted (9 years 1 month 4 days 8 hours ago) and read 13970 times:

Quoting Julesmusician (Reply 7):
How does it know what you want the N1/EPR to be on take off? How do you select it?

There is no fix N1/EPR for takeoff. The N1/EPR is determined by many factors, mainly runway length, weight, 2nd climb segment restrictions, flaps, runway conditions, OAT.. etc. After all these are taken into account, a certain N1/EPR would be determined by the pilot and the FMC for that particular takeoff and pushing of the TOGA switch would advance the throttles to this setting.

Quoting Julesmusician (Reply 7):
Will the TOGA switch automatically pitch you up when you reach take off speed or do you still have to manually pull back the stick to get the aircraft off the ground?

No. The TOGA switch is for throttle control purposes, it doesn't have anything in relation to any control columns.

Hope this helps  Smile



Boeing747 万岁!
User currently offlineNAV20 From Australia, joined Nov 2003, 9909 posts, RR: 35
Reply 9, posted (9 years 1 month 4 days 8 hours ago) and read 13952 times:

As I understand it, TOGA will apply and maintain 'maximum' power (that is, the required N1 level subject to not overstressing the engines etc.). It can also be relied on to advance all the throttles evenly.

Jet engines take some seconds to spool up and down. Doing the same job manually would presumably require the pilot (or more likely the second pilot) fiddling with the throttles and watching N1 until the aircraft was about halfway down the runway before he/she could be sure that all the settings on all the engines were right.



"Once you have flown, you will walk the earth with your eyes turned skywards.." - Leonardo da Vinci
User currently offlineHAWK21M From India, joined Jan 2001, 31712 posts, RR: 56
Reply 10, posted (9 years 1 month 3 days 23 hours ago) and read 13902 times:

When every second matters in a Go around,Its better to have one switch do your job,rather than multiple functions that'll cost those valuable seconds.
regds
MEL



Think of the brighter side!
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 11, posted (9 years 1 month 3 days 19 hours ago) and read 13878 times:

OK so there must be something wrong with Flight Sim then as when you hit the TOGA switch just before touchdown it places the aircraft into a pitch up attitude and advances the throttle fully forward, or maybe that is just for the go around part of it?

User currently onlineAAR90 From United States of America, joined Jan 2000, 3494 posts, RR: 46
Reply 12, posted (9 years 1 month 3 days 16 hours ago) and read 13850 times:

Quoting Julesmusician (Reply 11):
OK so there must be something wrong with Flight Sim then as when you hit the TOGA switch just before touchdown it places the aircraft into a pitch up attitude and advances the throttle fully forward, or maybe that is just for the go around part of it?

"Hit" the TOGA switch "just before touchdown" = Go-Around mode activated.  spin 



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineJulesmusician From , joined Dec 1969, posts, RR:
Reply 13, posted (9 years 1 month 3 days 16 hours ago) and read 13847 times:

Perhaps hit wasn't the right word - touch gently in a totally calm state - are right the GO mode is different from the TO mode...I think I am beginning to understand  Wink

User currently onlineAAR90 From United States of America, joined Jan 2000, 3494 posts, RR: 46
Reply 14, posted (9 years 1 month 3 days 9 hours ago) and read 13801 times:

Quoting Julesmusician (Reply 13):
right the GO mode is different from the TO mode...I think I am beginning to understand

First time I ever came across this feature it was named: "TO/GA"... meaning Take-Off and/or Go-Around switch. The "and" portion is the fact that the single switch has two functions. The "or" portion indicates you get either one or the other of the two functions, but never both at the same time. Even today I continue to use that particular spelling: "TO/GA." Keeps things simple for me.  old 



*NO CARRIER* -- A Naval Aviator's worst nightmare!
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17178 posts, RR: 66
Reply 15, posted (9 years 1 month 3 days 7 hours ago) and read 13782 times:

Quoting Julesmusician (Reply 11):
OK so there must be something wrong with Flight Sim then as when you hit the TOGA switch just before touchdown it places the aircraft into a pitch up attitude and advances the throttle fully forward, or maybe that is just for the go around part of it?

As I pointed out in the other thread, the "stock" 737-400 (and 747-400) in MSFS doesn't behave like the real plane, and the controls are MUCH simplified. Try Dreamfleets 737-400 for a more realistic experience. I believe something like 90%+ of the controls are in place, and the autopilot, FMC and so on actually work pretty much like in the real plane. For more detailed and realistic sims, you might also want to try http://www.phoenix-simulation.co.uk/

Note, though, that this is still not a "real" sim. It's just much more real than the watered down version in plain vanilla MSFS.


But I would also think that pushing the throttles on an aircraft with underslung engines such as the 737 to the stops would produce at least some some pitch up moment.



"There are no stupid questions, but there are a lot of inquisitive idiots."
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