Definition
An altimeter whose indication is stuck at a fixed value because its static port is blocked, preventing the instrument from sensing changes in outside air pressure as the aircraft climbs or descends.
Plain English
The altimeter needle stops moving and keeps showing the same altitude, even though the aircraft is actually climbing or descending. It looks like it is working, but it is not.
Context Anchor
Encountered in pitot-static system discussions, especially when studying what happens after a blocked static port.
Derivation
Frozen' here is used in the sense of 'locked in place' or 'unable to move,' not necessarily caused by ice (though ice is one common cause). The instrument is figuratively frozen at a single reading.
Why Pilots Care
Provides false altitude information that can lead to terrain conflicts, airspace violations, or loss of situational awareness in instrument conditions.
Analogy
It is like a clock that stops at 3:15. The displayed time is still a real time, but it is no longer the current time.
Grounding Statement
If current outside air pressure cannot reach the altimeter, the instrument has no new information and keeps showing the last pressure-based altitude it sensed.
Intuition Check
Do not assume frozen means the altimeter itself is covered in ice. Here, frozen means the indication is stuck because the pressure signal to the instrument is blocked.
Example Sentence 1
When the static port iced over in the climb, the altimeter froze at 6,000 feet even though the aircraft continued climbing.
Example Sentence 2
After the static port was cleared of ice the frozen altimeter resumed normal operation and began to show the actual climb.