In the last two weeks my dog has been attacked luckily not injured by a lab and airdale. Both times they were off lead and mine on lead has he has not recall and unless in a secure field has to stay on lead. He has now decided that he will get in first if a male comes towards him. Both times I have told the owners to put there dogs on lead as he is at a disadvantage and cannot get away if anything happens. Can anyone suggest a solution. One thing I am going to take on a friends advice is a pet correcter and will spray it at the other dog but my dog doesen't like the noise it makes and will also spook him.

Grisha Stewart has one possible solution. Keep some very high value treats with you. As you retreat from the offlead dog toss treats to it and behind it, all the while repeating in a loud but calm voice, "please call your dog to you".

If the other dog is in a very high state of arousal you can try standing infront of your dog and blocking by putting your hand out like a police stop sign, look very confident and in charge. Sometimes doing this and saying "no, no, off you go" can make the other dog think twice...you need to think Barbara Woodhouse (if you know who she was)- just seem very in charge. But I know if you are worried this is hard to do.

It is such a pain when people let their dogs bound up to another dog on lead. I always, always view another dog on lead as sacred space and I avoid or put my dog on a lead too.

I think it someone on here who suggested some time ago, to shout " call your dog please, mines infectious ! " lol, I've never tried it but I bet it would work.
You could try a good sturdy telescopic brolly, I got one that has a really powerful mechanism and it shoots out at a fair ole' rate, deters most dogs, even if they don't get a fright, you can use the brolly to block them.

Is it possible testosterone spike in your own dog is a factor?  He sounds young (not reliable recall yet) and it sounds like this has not happened before.  Not excusing the other dogs and owners but if this is a reason you may expect it to go on till his levels settle back down to normal adult levels.  Of course this is only a thing young intact males go through so I should have asked his age and sexual status first.

DArn, I'm sorry, I'd give you a link to this testosterone spike business but bing has taken over my search engine and I can't find it.

Anyone know how to get rid of bing?  Google worked better.

Older intact males can do this horrible thing of targeting young adolescent boys, it is literally a case of putting them in their place and is probably, as Jetstone suggests, triggered by a testosterone spike which will make your dog smell very male and be like a red rag to a bull to some other males. That may be one explanation- not very nice for your or your boy though. Can you remember if the dogs that went for him were intact males?

Actually it can happen with any other dog.  The spiking testosterone may be off putting to entire and spayed females and neutered dogs as well, though I agree intact males are probably the most threatened by it.  And, not to scare you or anything, but some neutered males are nasty to intact males at any stage.  The theory is they're jealous.  :) 

My boy is intact, unusual for a pet dog in N. America, and I do have problems with neutered males targetting him.  Oban won't fight back and will literally turn the other cheek, or flank, to them if he can't walk away.  One day we met three hitherto unknown dogs that tried to rough him up, much to their owners' surprise and dismay as they are not used to meeting intact males.

Yep, red flag to a bull.  :(  That's exactly how I've expressed it myself sometimes.

Regarding this testosterone spike, it's really incredible.  The source link I can't find right now says the level can spike to 7 times what it will be in adulthood.  SEVEN times, my gosh, it's a wonder we can't smell that, we feeble humans.  You'd think it would make their urine stink at least but I haven't noticed it.

I carry a dazer and also bite back spray with me since my dogs were attacked by a rottie when they were on the lead and also the rottie was on lead but his owner had no control. i will use both on any dog now that comes 'at' my dogs.

I would take your own dog to a good training class, that way he can be social with other dogs, and you can work on his recall and get the correct advice.
Dogs that are on lead often give signals to other dogs, and if he has been attacked previously he may be behaving in a threatning manner, which will set the other dogs off.
For the time being I would stick to areas where he is not going to meet dogs that are off lead. Then once he has been to training and is happier with other dogs, and you have a good recall in place, you can then begin to introduce him to other well mannered dogs preferably on a very loose lead, and then if there are no problems, off lead as well.
Did your dog have plenty of socialiastion with lots of different dogs as a puppy ?

He is 3yrs old but had no training for the 1st yr of his life when I got him, didn't know until afterwards. The Airdale was intact when the new owners got him but have now had him castrated. My dog usually loves all dogs and was this morning playing with a small castrated male and they were having a great time. He didn't  show any agression until this Airdale stood right up to him I tried to stop the other dog and also stood in front of him but he felt threatened the owner did nothing. It's possible because he was on the lead he felt he couldn't get away because when the met this other dog he was off lead in enclosed field. They had one previous and we had problems with that one.

Sometimes dogs react more when on lead than off, they are programmed for Fight or Flight. If they are not able to get away then the only option left is to fight.
Also when a dog is on lead even if you are not aware of it there may be tension on the lead when the owner sees another dog, or the owner gathers the lead up, this sends a message to the dog that something must be up, or that you are frightened. This can then trigger the dog to take a different stance, either because he thinks he is about to be attacked or that he feels that he has to protect you.
Very difficult to give any advice, or to say exactly what is going on, which is why I think you need to get the help of a good trainer, they should be able to help you find out the cause of why your dog is prone to attacks, help you with the recall and general obedience and how to take evasive action when necessary. This in turn will give you and your dog a lot more confidence when you find yourself in awkward situations.
Good Luck and let us know how you get on, if you let us know what area of the country you are in I am sure others on here will be able to recommend dog training classes in your area.