I would second Sailboat and ParrotGenie, and elaborate a bit more.
I grew up in horse arenas. Yes, it sounds like a good idea, but hold your horses first.
Donāt even think about flight outdoors until youāve done a few things first:
Recall Training
Recall in the safety of your home is complete different from recall in a new place. Parrots get distracted by new environments. Your bird will likely be hesitant to recall in a new place. Even if you bring them out to socialise in new environments all the time, you will need to train your bird to be able to recall in new settings (many default to a freeze or flight).
Bombproof Training
Now, no bird is going to be bomb proof, but you have to train for anything you can think of. Sure a horse arena sounds like a contained area, but what if someone opens the doors? And tbh, Iāve not encountered an air-tight horse arena before (but maybe thatās how because I grew up in a very real area); many of them have big open doors, at the very least.
And what about when it rains? The din of the rain patter on the roof can spook off horses and birds.
What about someone closing a door, or opening up a horse trailer just outside? Those sudden sounds can spook a horse and a bird. A sudden light streaming in can also trigger a bird to fly.
I jumped off a horse that bolted just from the sound of coyotes. And I know our little guy is alarmed when he hears crows and other birds of prey.
What if some idiot human starts distracting your bird? (Yes, I had a child throw a water bottle at Cairo before.)
These are all examples of sounds and distractions you need to train for.
Descent Training
Your bird is probably used to the height and safety of home. That means he might not know the basics of flight navigation - wind, steep descent, etc. You have to prepare him for the heights he might have to navigate from. Itās easy to go up, but itās another to go down. A bird who doesnāt know how to descend steeply is likely to get stuck in a tree/rafter for hours or even days (yes, Iāve seen this happen).
Stamina Training
This is contentious for some, but you have to read your birdās body language. A domesticated bird donāt have the stamina of wild birds because they just donāt get the flight time. And if they fly in the house, itās normally in short bursts (think a sprint versus a marathon). You need to train for a marathon. And tbh, itās easy to tell if a bird is new - they donāt glide worth a beep. But you also need to learn how to not push your bird too hard. Cairo often flies to me, checking if he can land; Iāll wave and ask him to ākeep goingā; if heās tired, he hovers like a helicopter and then I have it land immediately, but if heās got a tiny bit of energy left, heāll go for another loop around. Now, if you donāt establish this basic communication safely, your bird will land elsewhere.
Upkeep
You must never assume your bird is fully-trained and itās a done deal. You must keep practicing as if your bird is untrained. People who think āoh, heās fully-trained, weāve done so many good flightsā are also the most likely to lose their birds. You keep training the basics.
Other things to look up - boomerang, ascending, contact call, etc.
Disclaimer:
Do NOT attempt flight outside your home until you have established the basics of above. And when you step outside your home to conduct training, have your bird on a harness and start with recall that just requires your bird to HOP from training perch to your hand.
The free-flying community where I live also recommends never putting your bird on a perch other than the training perch or yourself. You do NOT want your bird to think that perching just randomly anywhere is safe - they do not have the instincts/experience of wild birds. They also recommend training your bird to recall to one person and one person ONLY. The more people your bird is trained to recall to, the higher the risk.
And most importantly:
The first thing the free-flying community tells anyone considering outdoor flying:
If you do want to attempt flight out of your home, you must accept the fact that your bird might get lost.
Full stop. Period. This is a risk you must be aware of and must be willing to take. No matter how well-trained your bird is, you cannot account for everything (Murphyās Law to live by).