// Global Variable
new ChangeInterior_Timer[ MAX_PLAYERS ];

// Timer
ChangeInterior_Timer[ playerid ] = SetTimerEx( "ChangeInterior", 10000, true, "i", playerid );

// Callback
forward ChangeInterior( playerid );
public ChangeInterior( playerid )
{
    new _P[ MAX_PLAYERS ] = 0;
    
    switch( _P[ playerid ] )
    {
        case 0:
        {
            // Do your code for the Plane Interior
        }
        case 1:
        {
            // Do your code for the Airport Interior
        }
        // And so on...
        // PS: At the last case, in this case, '1', use 'KillTimer( ChangeInterior_Timer[ playerid ] );' and '_P[ playerid ] = 0;'.
    }
    _P[ playerid ] ++;

    return 1;
}

// Making a command to start the timer
public OnPlayerCommandText(playerid, cmdtext[])
{
    if(strcmp("/start", cmdtext, true) == 1)
    {
            /*
                Here you should set them to the plane interior 
            */
            SetTimerEx("MyCallback", 10000, false, "i", playerid); // Calling the timer (10 seconds)
            return 1;
    }
    return 0;
}

// forwarding MyCallback
forward MyCallback(playerid);

public MyCallback(playerid)
{
    // When 10 seconds passed
    /* 
        Here set them to the airport interior 
    */
    return 1;
}