My family's experience at Changi Airport immigration on our return from our South Korea and Australia trips was a big letdown.

On our return from South Korea at Terminal 4 in March, my wife encountered difficulties with her fingerprint check at the manned all-passport counter. She was directed to a Singapore passport "satellite counter", where she had to queue all over again.

Again her fingerprint check ran into issues. After three tries, the staff wanted to direct her to yet another counter, but she objected and was finally allowed through.

My brother-in-law also failed the fingerprint check at the T4 auto-entry the first time, was redirected to the Singapore passport "satellite counter", and redirected once again when this also failed. On the fourth attempt, he finally cleared it.

His wife, my sister-in-law, also had a problem at the T4 auto-entry despite retries using both thumbs. A staff member eventually came and cleared her through after another two to three tries.

On our return from Melbourne in May, my brother-in-law's experience was frustratingly repeated at Terminal 2.

Interestingly, the four of us have been to Malaysia by coach twice in recent months without any issue.

I wonder how many Singaporeans have had similar experiences?

Why do such processing inconsistencies exist, especially at the relatively new T4?

More importantly, what impact could such inconsistencies have from a security perspective?

Given the nation's big investment in infrastructure and systems, such system hiccups need to be addressed.

Ng Chor Chye