Definition
An older display device, typically a cathode ray tube (CRT), used in earlier electronic flight instrument systems to present flight information on the primary flight display or multifunction display. The picture tube uses an electron beam scanning a phosphor-coated screen to produce the image the pilot sees.
Plain English
The screen technology used in older glass cockpits to show flight information, similar to the bulky tube screens used in old televisions before flat panels.
Context Anchor
Seen in discussions of older electronic flight instrument systems and how their cockpit displays produce an image.
Derivation
The phrase comes from early television terminology, where a cathode ray tube produced the on-screen 'picture.' The same display technology was adapted for cockpit instruments, and the name carried over.
Why Pilots Care
Pilots flying older glass-cockpit aircraft may still encounter picture tube displays, which behave differently from modern flat-panel screens in terms of brightness, glare, and failure modes. Knowing the term helps when reading manuals or troubleshooting older systems.
Intuition Check
Do not read “picture tube” as a tube that carries pictures like a pipe. In this context, it means an older screen device that creates the picture you see on an instrument display.
Example Sentence 1
The older EFIS in this aircraft uses a picture tube, so the displays take a moment to warm up after power-on.
Example Sentence 2
Older aircraft still in service may have a picture tube that requires warm-up time before the instruments become visible.