This is a little long (sorry) but maybe it will prevent someone doing to their sweet little bird what I did to mine - yes she still loves me.
Here it is:
This is a long post, but I think with some of the new people who have been posting and many more who read but don’t post who have new pet tiels, it may in the least save them frustration, and my prevent them from doing to their beloved pet what I did to mine:
Here it goes: I tried using the feather tether a few months back. She was about 5 months old when I purchased it. I thought I was starting slow (being new to the world of birds – now, slow has a new meaning to me); I would put it on her (yes she fought it) leave it on for a couple of minutes and then take it off. One of the mistakes I admittedly make was not doing it everyday. Timing was bad with work and blah blah blah. And I didn’t think of checking for a website for more info on it.
Then I got the idea of putting it on her but cuddling her the whole time so she would get used to the thing being on her but also having me for the reassurance and security.
Then the biggest blunder of all time happened. I got the harness on her and cuddled (no blunder yet) for about 15 minutes, maybe longer. I put her on my shoulder to see how she would be with it - not good. She started picking at it and moving her feet to get it off. Well, her foot got
stuck so I had to un-stick it. Then I tried to get it on her again, and my husband came over to help out...
Ok this is it... he was holding her and I was manipulating the blasted thing around her little body and under her wings to try and clip it around her chest – failing miserably. The clasp is a top and bottom type squeeze
instead of on the sides. So you have to put your finger between the clasp and the bird so you can put your other finger on top of the clasp to push it in the slot. So the 2 stupid humans who are more interested in getting it
clasped, I wasn't paying total attention to my beautiful feathered baby. This is a total of about 2-3 minutes this time around. I finally looked at her and not the stupid clasp and thought she was going to have a heart attack!!!
Oh my God!!!

Stop!! We have to get it off!! I tried to get it off as fast as I could without totally killing the poor thing, her neck was tretched out eyes popping and mouth wide open as if she was screaming with no sound coming out!!! This happened about 7pm on a Sunday, my husband threw the harness down on the floor and cursed it out and stomped on it, I held her close she was shaking and that was all she did.
We passed her back and forth between us to cuddle her and reassure her that we really do love her. We told her she was a good girl and we loved her. We tried giving her treats - wouldn't take it, wouldn't eat anything or drink, this went on for 5 hours - we were so upset about the whole thing. She finally started to eat a little about midnight
We wanted her to get used to it so we could take her outside to get some fresh air and sunshine. I thought of trying the flight suit so it could double as a diaper but we just aren’t sure if she is ready yet to try anything new.
Up till then we could put her just about anywhere and give her almost anything to play with and she was always accepting of new things. Now, she won’t even go near a wreath I picked up for her to play and swing on, and it’s been in her view for over a month.
I know I didn’t prepare myself well enough or work with her enough on being handled and touched on her body before trying the tether. The tether for tiels is very small and confusing to get on the bird, so I admit the mis-hap is my fault for not being well versed in putting it on her
before I tried to put it on her. I’m sure there are people out there who have had great success with it – I just wish I were one of them.
She still loves us to my surprise! I believe she truly loves us unconditionally. Please learn from my terrible mistake and make sure you know how to put it on before you try putting it on your pet. Take it slow and get her to feel comfortable with it before putting it on.
I hope this helps at least one person not to do what I did.
That happened last May - Memorial Day weekend. I was told to treat her like a "big bird" and not baby her after that so it won't reinforce the negative situation.
I started to do that by putting her on the wreath mentioned in the story and am happy to report that she has almost finished chewing it up

I did purchase a flight suit, have it haning in her cage, she hasa nibbled on it but everytime I bring it near her she avoids it like the plague. I just hope I didn't miss the window of opportunity to get her used to it.
If any of you are interested in training your tiel with some sort of flight suit/harnes do it while they are babies - you'll save yourself and your tiel alot of frustration. Also I can not reccommend the feather tether. To me it is to complicated and bulky for a tiel. For a cockatoo, amazon etc - they have a different type of harness - more like that of a dog harness, so it's easy on the larger birds.