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Tidalforce
1st Apr 2010, 12:31
Hi,

Do any A320 operators have a packs off SOP for all take offs? If so does anyone with a medical background have any insight as to the potential adverse affects on the innocent ears of crews on a long term basis....?? Cheers ! Safe flying,

fredgrav
1st Apr 2010, 21:08
Hi Tidalforce,
as far as I know every takeoff is allowed either with PACKS OFF, or APU ON + PACKS ON ... honestly can't see a good reason for an airline to inhibit the use of packs. Anyway for any PACKS OFF takeoff, the first PACK ON selection comes upon reaching Thrust Reduction Altitude, while the second at FLAPS UP/CLEAN CONF: as the two events never happen together, PACKS are always turned on individually, and consequentially passenger/crew comfort on pressurizing the aircraft is significantly improved.

Happy Takeoffs and indeed ... Unpressurized Landings ! :ok:
fredgrav

gusting_45
1st Apr 2010, 23:30
In our company every T/O is PACKS OFF. It's not a problem and I can't recall anbody mentioning any medical concerns! One Pack ON at thrust reduction, second one ON after 10 second interval. Not an issue.

Flew for several years up to FL100 on light turbo-props as have many others with no presurisation at all. I really fail to see that there is an issue with this at all.

Dan Winterland
2nd Apr 2010, 04:25
Mine does.

The packs off T/O allows a degree or two higher on the flex which saves on engine wear.

greenslopes
2nd Apr 2010, 04:32
On the 737 the bleedfrom the engines can be selected off for takeoff and is quite routine, in this instance the apu will provide the necassary bleed air for the one pack. Takeoff with the packs off is quite unusual as their will be something of a noticeable pressure change upon introduction of bleed air and pressurisation. So in answer to your query, Takeoff with packs off is unusual, however takeoff with bleeds off is quite routine.

Tidalforce
2nd Apr 2010, 23:46
Cheers for that folks,
Seems alot of airbus operators use the no packs take off and all the boeing folk keep the packs on. Keeping them on is alot better for you ears on a long term basis! There all counting pennies these days tho...

Denti
3rd Apr 2010, 08:35
We have both fleets, and yes, on the boeing we usually do bleeds on packs on departures. On the airbus fleet it is usually a packs off departure. However i never noticed any pressure bump during the airbus departures at all. On a boeing it can be a pretty strong thing, on the airbus it simply doesn't happen.

Can't really see any danger for your ears there. Much more dangerous is flying with an undetected cold, that can really harm your ears.

tom775257
3rd Apr 2010, 10:25
I've worked for two airlines flying the airbus 320, the first one (a European flag carrier) SOP packs on take off, second airline (UK charter/sched) SOP packs off take off.

waren9
3rd Apr 2010, 10:37
Keeping them on is alot better for you ears on a long term basis!


Why do you think that?

People have been flying around unpressurised for decades with no problems. So long as you dont fly with a cold or blocked sinuses then theres no problem.

:confused:

Field In Sight
3rd Apr 2010, 18:53
On a packs off take off, the pressurisation system is still working and will try to maintain the pressure at take-off during the initial part of the climbout.

Once the packs are switched on, the outflow valve will automatically compensate by opening. i.e. no major changes to the cabin pressure.

I've never felt any pressure differences, that's on the airbus though.

FIS.

demomonkey
3rd Apr 2010, 19:05
In discussing this same point today, it was pointed out by someone much wiser and cleverererer than myself, that;

On the 320, if performing an APU->Pack Take-Off due performance restrictions and the APU developed a fire the APU bleed would be automatically closed, the engine bleeds would then open and in the middle of trying to fight a fire you might inadvertently find that obstacles in the take-off cone would look larger and closer than is health.

However on the 737 Classic which isn't blessed with such intelligence the problem wouldn't occur.

Therefore maybe SOPs for 320 APU->Pack Take-Off should be to also switch off both engine bleeds as a 'belt and braces' measure?

fredgrav
3rd Apr 2010, 20:49
Therefore maybe SOPs for 320 APU->Pack Take-Off should be to also switch off both engine bleeds as a 'belt and braces' measure

Hi Demo,
as for SOP's, APU bleed is not allowed if wing anti-ice is to be used: that's the only restriction you must adhere to for every PACKS ON takeoff ... but no engine bleeds off policy !

fredgrav