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Why Do Planes Stall?  
User currently offlineNaimas From , joined Dec 1969, posts, RR:
Posted (14 years 10 months 4 weeks 10 hours ago) and read 1559 times:

I have noticed that several flights I have had (especially from SEA for some reason) that when we are beginning to back away from the terminal suddenly everything goes dead, lights, air, everything, then they pop back on and then you will get to feel all comfortable and boom it happens again and sometimes again when you are taxiing.

It seems like everything stops and the sound of sudden silence just destroys any peace in the cabin and people start going Oh no. I HATE that. Is it just a switch of power or something that shouldnt be?


Thanks

6 replies: All unread, jump to last
 
User currently offlineAC_A340 From Canada, joined Sep 1999, 2251 posts, RR: 1
Reply 1, posted (14 years 10 months 4 weeks 10 hours ago) and read 1475 times:

Because they plane uses something called bleed air from the enginges to power all of this. And at the gate itis hooked up to the terminal. On pushback there disconnected, hence the power. The need the power to start the enginges so thats another answer. I'm not sure about taxining though, anyone?

User currently offlineDaniel From Sweden, joined May 2005, 0 posts, RR: 0
Reply 2, posted (14 years 10 months 4 weeks 9 hours ago) and read 1466 times:

I dont think that the bleed air from the engines has anything to do with the electrical power on the aircraft.

User currently offlineJETPILOT From United States of America, joined May 1999, 3130 posts, RR: 29
Reply 3, posted (14 years 10 months 4 weeks 8 hours ago) and read 1465 times:

When switching from an external power source to ships power, such as from APU power, the relays that allow engine generators to come on line need to sense a loss of external power before closing. Hence the loss of lighting.

An APU even though it is inside the plane is treated as an external power source by the aircrafts electrical system.

On pushbackbefore starting engines you will also notice your eyeball sockets providing air conditioning aren't working. The bleed air from the APU is being used for engine start, and the AC packs have been turned off.


User currently offlineJETPILOT From United States of America, joined May 1999, 3130 posts, RR: 29
Reply 4, posted (14 years 10 months 4 weeks 8 hours ago) and read 1468 times:

When switching from an external power source to ships power, such as from APU power, the relays that allow engine generators to come on line need to sense a loss of external power before closing. Hence the loss of lighting.

An APU even though it is inside the plane is treated as an external power source by the aircrafts electrical system.

On push back before starting engines you will also notice your eyeball sockets providing air conditioning aren't working. The bleed air from the APU is being used for engine start, and the AC packs have been turned off.


User currently offlineNaimas From , joined Dec 1969, posts, RR:
Reply 5, posted (14 years 10 months 4 weeks 7 hours ago) and read 1463 times:

Thanks for the info.

I wasnt scared, but I do feel better.

Perhaps its bad timing when they switch power but my USAirways 757 had the video monitors pop off then on then off then on again during instructions.

Since it was the switch over like you said-perhaps USAirways should wait until disconnected to start their video since the site of a half a dozen monitors going dead doesnt exactly improve ones first impression of a flight!  


User currently offlineUS521 From , joined Dec 1969, posts, RR:
Reply 6, posted (14 years 10 months 3 weeks 6 days 22 hours ago) and read 1443 times:

No LIft!!!!!!!!!
US521


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