I have the following array that is created by a form. I need to access the various parts of this and create an SQL insert into a relational dB linking table. The array looks like this:
$a_id= Array (  => Array (  => 1  => 2 )  => Array (  => 2  => 3 )  => Array (  => 1  => 3 )  => Array (  => 1  => 2  => 3 ) )
So what this represents is the key value is an id of an airport and the value of this key is another array, which represents up to three services available at each airport. So, for example, airport with the id of 1 has two services available with id's of 1 and 2. The airport with id number 8 has all three services available 1, 2 and 3.
However, I am having trouble accessing this array. I have tried to access for instance the first airport by using $a_id but no luck. Never mind accessing the associated array to airport 1. How would I access the various parts of this array?