A319 Packs off for TKOF ?
Thread Starter
A319 Packs off for TKOF ?
Just doing a conversion course for the A319 for a UK operator that per SOP selects Packs off for TKOF. Is this standard for Airbus ??
Does anybody know why ??
Coming from the 737 (Scandinavian operator) Packs were selected off when needed performance wise.....
Rgds. OY
Does anybody know why ??
Coming from the 737 (Scandinavian operator) Packs were selected off when needed performance wise.....
Rgds. OY
Join Date: Jan 2001
Location: Around the world.
Age: 42
Posts: 606
Likes: 0
Received 0 Likes
on
0 Posts
I reckon: Packs off take-off = more fuel efficient and I would guess less engine wear due to decreased EGTS. (obviously not running APU).
At the airline I work for it is pretty much always packs on - if we require engine bleed off for performance we run the APU with APU bleed on for take-off.
At the airline I work for it is pretty much always packs on - if we require engine bleed off for performance we run the APU with APU bleed on for take-off.
Join Date: Jan 2005
Location: uk
Posts: 1,266
Likes: 0
Received 0 Likes
on
0 Posts
What variation in psi do you think there is in the bleed duct between engines idle and engines at CLB thrust? I'll have look today but I can't imagine it would be enough to worry about. Besides, engines are more expensive than Packs.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
Engine bleed air doesn't route directly to the packs; There's a pressure regulating valve in between so the pressure variation driving the packs is minimal.
Otherwise - think of the bleed pressure variation between SL takeoff compared to idle at top of descent.
Otherwise - think of the bleed pressure variation between SL takeoff compared to idle at top of descent.
Join Date: Jul 2000
Location: Germany
Posts: 91
Likes: 0
Received 0 Likes
on
0 Posts
Packs on Engines is standard unless T/O performance requires the Engine Bleeds to be selected off.
If the T Flex goes below 45°C we are recommended to switch Engine Bleeds Off to reduce Engine wear.
In these cases 'Packs on APU' or 'Packs Off' is crew discretion. If the flight is booked well and/or it's hot outside APU might be the better choice.
After De-Icing we normally use 'Packs Off' in order to avoid the run-up which was necessary to clear residiual fluid off the engines. If there is a longer delay between end of de-icing and take-off 'Packs on APU' is a lot more convieniet to the pax.
Regards, MAX reverse
If the T Flex goes below 45°C we are recommended to switch Engine Bleeds Off to reduce Engine wear.
In these cases 'Packs on APU' or 'Packs Off' is crew discretion. If the flight is booked well and/or it's hot outside APU might be the better choice.
After De-Icing we normally use 'Packs Off' in order to avoid the run-up which was necessary to clear residiual fluid off the engines. If there is a longer delay between end of de-icing and take-off 'Packs on APU' is a lot more convieniet to the pax.
Regards, MAX reverse
Join Date: Jan 2006
Location: on the Blue Planet
Posts: 255
Likes: 0
Received 0 Likes
on
0 Posts
OSCAR YANKEE
Also probably flying for the same company, the procedure as far as I know is to save wear and tear to the engine, as mentionned by tom775257.
We used to have the same procedure on the A310... whereby some other aircraft have some auto shutdown systems.
Also probably flying for the same company, the procedure as far as I know is to save wear and tear to the engine, as mentionned by tom775257.
We used to have the same procedure on the A310... whereby some other aircraft have some auto shutdown systems.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
More and more operators are changing to pack off tack-offs.
Join Date: Jan 2007
Location: in the mist
Posts: 563
Likes: 0
Received 0 Likes
on
0 Posts
The hardest part of taking off with them off is remembering to switch them on again. I struggle with off/on stuff so I'm lucky enough to work for an outfit that leaves them on unless performance requires otherwise. Has anyone done a PAX off take-off? That solves a few performance issues too. 
Join Date: Aug 2003
Location: Hampshire physically; Perthshire and Pembrokeshire mentally.
Posts: 1,611
Likes: 0
Received 0 Likes
on
0 Posts
Packs-Off Take-Off
The hardest part of taking off with them off is remembering to switch them on again.
In any event, once you have some time in the aircraft, you will become sensitive to environmental factors which will prompt you to switch them on before them ECAM gives you a caution - it's suddenly getting warmer in the flight deck, for example or the sound is subtly different because there is no pressurisation/air conditioning.
I've done a few PAX-off take-offs as well - it goes up like a dingbat!
OSCAR/YANKEE
The reason is that it enables a higher TFlex to be used so it reduces engine costs significantly over the long term.
Join Date: Sep 2004
Location: Virginia, USA
Posts: 74
Likes: 0
Received 0 Likes
on
0 Posts
Think we fly for the same opperator OY and I was wondering whether switching them on with the engines going amost full pelt does the packs any harm?
Why after flap retraction, I don't know? Perhaps that's just a convenient memory jog to do it, and it is long enough after the first pack on so to avoid a possible pressure surge which the system would experience if both were turned on at the same time.
Join Date: Jul 2000
Location: Germany
Posts: 71
Likes: 0
Received 0 Likes
on
0 Posts
KC Driver, you're correct, that's the reason.
If you have a high acceleration altitude (retracting flaps a lot later than usual) it's absolutely fine to switch the second pack on 30 sec after you have switched the first pack, although the flaps are still out.
If you have a high acceleration altitude (retracting flaps a lot later than usual) it's absolutely fine to switch the second pack on 30 sec after you have switched the first pack, although the flaps are still out.
Join Date: Nov 1999
Location: UK
Posts: 163
Likes: 0
Received 0 Likes
on
0 Posts
We always use packs off take-off, turning them off as we enter the RWY then reselecting (10 sec gap between) when CLB THR is set. There is no problem remembering to do it as it is normal ops and no damage or fluctuations have happened to my knowledge with the packs. Increases FLEX by significant margin thus extending engine life as the 'damage' in terms of wear is exponentional with temp at the higher temps.
Join Date: Jun 2005
Location: Citizen of the World
Posts: 174
Likes: 0
Received 0 Likes
on
0 Posts
The real reason in most cases is to get the maximum FLEX temp for the takeoff. Typically you'll get between 3 and 6 degrees higher flex with PACKS OFF. This equates to lower engine EGT thus lower wear and if the engines are leased (which many are nowadays) lower monthly lease costs.
Now if you take off with PAX off, the 320 thinks it's a Boeing!!
Now if you take off with PAX off, the 320 thinks it's a Boeing!!
