I used to be working there then I did a jump. And drawing about 5.4k now. Still low compared to some of my new colleagues at my position (6k to 7k).

10 years getting 4.1k is actually normal in ST. Typical yearly increment is only 2 to 3%. Promotion is around 8 to 10%. Unless you are a "scolar" or Top Talent your chances for promotion is not high. You really need to excel (as a farmer), and outperforming scholars and TT. Even then promotion is not garanteed.

And ST being ST, SAF officers are parachuted into higher management posts. Chances of moving up is even smaller. In fact almost zero. You need to handle many high profile projects to move up.

Some of my ex-colleagues at M2 grade (12 to 15 years in ST, their first job) were only commanding 5k. And these people can really perform and manage vendors. Thats why ST engineers are in hot demand outside as ST is a good training ground. A check with IDA or DSTA you will find that their HR likes ST engineers as they can perform and stay the longest. Your friend might want to consider jumping.

I also believe your friend has been seeing new hires coming in at 5k to 6k with M1 and M2 grades, with lesser years of work experience.

When I went for my interview for my new job, my present supervisor was asking me

"10 years experience and you are getting 4.4k?"

AKA

"10 years already and your pay is so low? Why didnt you leave?"