Originally Posted by
Master of FiFi
"The Book" says:
Using external conditioned ground air simultaneously with aircraft air conditioning packs is prohibited to prevent chattering of the non return valve.
I know we are mainly discussing the 737 here, but that is all the Airbus FM says about it. It may be worded differently in the guppy manuals, but if you can point out to me where it says I can't use the packs with with the external air turned off but the hose still connected, I will bow to your misguided efforts to be a company man.
You're reading too much into it. What xhooker said. Ground air "connected" means the air is on. Hose hooked up but air not on doesn't count. Hit the OFF button on the walkaround, then packs ON in the cockpit.