Elaine Willis, 49, said she panicked after realising she had picked up 16-year-old son Jamie's passport by mistake for the round trip from Manchester to Edinburgh.
However, she was surprised to board the Flybe flight without incident, and also encountered no difficulties returning from the capital.
Mrs Willis, of Stockport, said: "I couldn't believe it when they let me through - none of us thought for a minute that I would get through on a young boy's passport. The checks were clearly very poor."
She added: "Mine was an entirely innocent mistake with no bad intent at all, but we all know that there are people out there who want to bring terror to the skies above Britain, Europe and the USA and they need to be caught before any more people die."
Passports are not required on domestic flights as passengers do not pass through border control, and security staff only check boarding passes.
Flybe asks passengers to carry photo ID, but this can also include a driving licence or travelcard.
A spokesman from Edinburgh Airport said: "There are no legal obligations for a passenger to carry their passport when flying within the UK.
"When flying domestically, each airline specifies its own ID requirements."