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Reading this article regarding an Alaska Airlines 737 Flight that had to turn around back to the gate. There was a following statement:

At the gate, passengers were unloaded five rows at a time, to minimize the risk that the plane would tip under extra weight of fuel.

My general understanding is that the fuel tanks are usually placed near the COG (wings, cargo tanks). Assuming the tanks are still full, why would unloading of passengers all at one time possibly cause the plane to tip? Or is this bad reporting?

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  • $\begingroup$ I dont know about fuel or this aircraft type in particular. But i have seen occasions where smaller aircraft (most recently a metroliner) tip backwards onto its tail because the baggage was loaded before the passengers boarded so i wouldnt be suprised if this was theoretically possible. $\endgroup$ – Minnie Oct 15 '15 at 9:12
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    $\begingroup$ Totally off topic, but that article speaks volumes for Alaska Air! My son will be stationed in Fairbanks, AK in about a year, and they just moved to the top of the list of choices! $\endgroup$ – FreeMan Oct 15 '15 at 12:51
  • $\begingroup$ @FreeMan I've always heard great about Alaska Air, wish I could take them more but unfortunately SFO is a United / VA hub $\endgroup$ – chickenricekid Oct 15 '15 at 16:31
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The 737-900ER has (two) axillary fuel tanks in the aft cargo compartment, behind the wing (and center of gravity) with ~3400l capacity for increasing range (from 2800nm to 3,200nm).

In usual conditions, unloading of passengers wouldn't be a problem as the fuel would've been used up; However, as this was an overweight landing with full fuel tanks (the auxiliary fuel tanks weigh ~ 3t), the crew are just being cautious to prevent any incidents.

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  • $\begingroup$ I see. Just as a followup, at what point do they fill the fuel tanks? I was always assuming the pumping started prior to passenger boarding, which would lead to a similar risk $\endgroup$ – chickenricekid Oct 15 '15 at 16:32
  • $\begingroup$ I don't know what the procedures are on a 737 but some aircraft have their front gear tethered to the ground so it can withstand a certain amount of cog shift without tipping. That was done when loading cargo containers into a FedEx DC-10 since it would be tall heavy while the first several cans are loaded. $\endgroup$ – TomMcW Oct 15 '15 at 18:40
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The 737 had a tendency to tail tip as can be seen here and here. They were just being diligent and of loading people in a timely and organized manner to avoid that. You can read up on it here as well.

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  • $\begingroup$ Sounds like the second link you provided of the Magala incident wasn't due weight distribution, but actually due to the airbridge moving up while the L1 door was open! pprune.org/rumours-news/… $\endgroup$ – chickenricekid Oct 15 '15 at 16:37

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