Corrie Mckeague, based at RAF Honington in Suffolk, disappeared after a night out in Bury St Edmunds on 23 September.
The gunner was last spotted on CCTV at 03:24 BST walking alone, but Nicola Urquhart said there was "not one image" of him leaving the town on foot.
She said: "I don't think Corrie is dead yet - I know people will be thinking 'something's happened' [but] I don't."
It was thought Mr Mckeague, 23, who was out with RAF colleagues on 23 September, stopped for a nap in a doorway before setting off to walk the nine miles (15km) back to his base early the following morning.
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Mrs Urquhart, of Dunfermline, Fife, said Suffolk Police has looked at "loads more CCTV" and "he is not seen leaving the area".
She said: "They are quite certain, on foot, that he can't be seen leaving. Somebody can't just disappear.
"He could have got into a vehicle, but not his own - his own was still parked up the road."
Mrs Urquhart said: "If somebody has hurt him, if something's happened accidentally, are they just going to keep on putting us through this turmoil?
"As a mother, I don't care if the police don't speak to you, but tell me where he is."
Police said they did not believe Mr Mckeague still had his mobile phone after data showed it moved to Barton Mills, matching the route of a bin lorry.
The phone has not been used since it was pinpointed to the location, which is about 10 miles (16km) from Bury.
Mrs Urquhart, who is a police family liaison officer, said her job could be both "a curse and a blessing" as she dealt with her son's disappearance.
"It's truly horrific some days, because I'm a police officer and I understand - and then other days it's such a help," she said.
The mother of an airman who went missing 13 days ago believes her son is still alive.