The star - who played Heather Trott in the BBC soap - said airline staff probably know when somebody needs a seatbelt extender, and could organise it quietly so as not to embarrass passengers requiring them.
Sharing her thoughts in a video on Instagram, she said: "The staff seeing that someone might be a little bit larger, you should know your plane by now.
"And you should know whether somebody needs an extra thing (seatbelt extender) so they don't have to buzz for it or do those things that they sometimes feel a bit embarrassed about asking because it's drawing attention to themselves."
She went on: "When you see somebody who you know won't fit into your plane seats, give them the extra bit of belt as they come on.
"Help them out, it's not fair."
Fergison, 56, had shared another video a little earlier, saying that she was fed up of shops sticking plus-sized or curvy clothing at the back or in a corner as it made people feel "uncomfortable".
She also said it wasn't on that some women's clothes stores carry such a small collection of garments for larger ladies.
Wrapping up her video about airlines, she told her followers: "I'm on a right rant today.
"I just think that we are body shaming people so bad at the moment."
"Just help people out and stop flipping well doing this rubbish," she urged.
Fergison is best known for starring as Albert Square's Heather from 2007 until 2012.
Her other small screen credits include Middlemarch, Doctor Who, The IT Crowd and Big School.
In 2012 she was a contestant on reality show Celebrity Big Brother.
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