Air Gapped

Your twenty years in IT just got called legacy.
There is a control room where that word means keep it running.

You have sent the applications. You have rewritten the resume four times, taken the graduation year off, and watched the same polite rejection arrive from roles you could do in your sleep. Somewhere around the two-hundredth one, a quieter thought arrived: it is not the resume, it is the year on it. You are not imagining that. AARP's 2025 research found that about 64 percent of workers over 50 have seen or experienced age discrimination at work, and the single most common form is the assumption that older employees are not tech-savvy.

Here is what almost nobody tells you next. You have been aiming at the one market where your experience is priced as a liability, and ignoring the one twenty minutes down the road where it is priced as judgement. Water authorities, electric utilities, councils, food plants and factories all run technology - networks, servers, remote access, backups, accounts, patching - sitting underneath machines that move water and voltage and steam. Those systems are being connected and secured right now. The people who know how to do that work are not in the building.

This field guide is the crossing. Twelve chapters take you from the language to the offer: what operational technology actually is, and why the plant floor thinks differently from the data centre; the Purdue model that every OT conversation is secretly built on; how to translate what you already did in IT into sentences a plant manager recognises; the four real doors in - OT networks and systems, SCADA and historian support, controls integration, and OT security; which free standards and public material to learn from, and which expensive courses you can safely skip for now; how to find and approach the employers in your own region who never advertise where you are looking; and how to answer the interview question about why availability and safety outrank everything you were trained to protect first.

It is a field guide, not a pep talk. Every figure in it is attributed to a named organisation with a date - AARP, the SANS Institute's ICS and OT surveys, the American Water Works Association - and where the evidence does not exist, the book says so instead of inventing it. It leans on material that costs you nothing: the ISA and IEC 62443 standards family, CISA's published resources, NIST's operational-technology guidance. It will not sell you a certification, quote you a salary, or promise you an outcome. It tells you what the work is, what gets you read, and what to do about it.

You finish something on the first night. Chapter one ends with a one-page crosswalk sheet: every skill you actually have in the left column, its plant-floor equivalent and its Purdue level in the right, three rewritten resume lines at the bottom, and a named list of the critical-infrastructure employers within an hour of your front door. No purchase, no course, no login. One evening - and for the first time in months you are looking at a door that opens toward you.

You are not obsolete. You have been standing on the wrong side of the wire.