Haha, I'd love to know where those numbers come from.
I'm quite significantly more than 5 years and my pay slip says:
Standard rate (for a captain): 12768
Experience pay (how long you've been there): 1062
Accommodation: 550
Per diem (it's called something else but we know what this means): 976
So, that's 15356
They'll doubtless argue about additions, so let's look at those.
I get a 1000 pension addition that then is deducted for a pension contribution.
There are additional hotel/accommodation allowances depending on exchange rates and the difference in what the hotel is charging and what they're paying. This is subjected to the most complicated formula known to man and nobody understands it. The main point being is that it is only an addition to make up for shoddy exchange rates and the fact that they don't pay you enough in the first place to pay your hotel bill.....so you're not getting any extra, just what should come under the accommodation part of your salary.
There are landing allowances paid only to captains. Basically it's $80 when you do a double landing in the crappy hours of the morning. It's supposed to make up for the $500/month they stole from the AJV captains when they combined the companies but it doesn't and is a complete farce. You might see an extra $240/month on a normal month.
They are probably factoring in the $2000 commuting allowance but if you use the C class option then that is removed entirely from your salary. If you slum it down the back of economy on standby and pocket an extra $1000/month after tax, then well done you and thanks for giving the company the idea that commuting long distances in that manner is acceptable.
If you use the C class option and get all the allowances above then your pay check will say closer to 16220 and that's > than a 5 year captain.
The basic answer to your query, though, is that the basic salary does increase after 5 years and you'll be able to be able to buy an extra $20/month of beer on that HUGE increase. Don't go spending it all at once and don't believe the obvious bu*#%^it that's being promulgated on the agency websites.