Definition
The minimum altitudes published on an instrument approach chart for the segment in which a pilot reverses course to align with the final approach. In very cold conditions, the true altitude flown will be lower than the altimeter indicates, so corrections may be required to ensure the aircraft remains at or above the charted minimum during the procedure turn.
Plain English
The lowest altitudes you are allowed to fly while turning around to line up with the runway during an instrument approach. When it's very cold outside, your altimeter can read higher than you actually are, so you may need to add a correction to stay safely above terrain.
Context Anchor
Seen on instrument approach charts and in cold-weather altimeter-error discussions, especially when checking which published approach altitudes need temperature correction.
Derivation
A 'procedure turn' is a charted maneuver used to reverse course on an instrument approach. The 'altitudes' part refers to the minimum heights published for that segment of the approach.
Why Pilots Care
Failure to apply the cold-temperature correction can result in reduced terrain and obstacle clearance.
Grounding Statement
On a very cold day, the altimeter can make the airplane seem higher than it really is, so a published procedure turn altitude may need an added correction before it is flown.
Intuition Check
Do not read this as “any altitude used during any turn.” Here, procedure turn altitudes means the specific published altitudes for the charted course-reversal part of an instrument approach.
Example Sentence 1
With an outside air temperature well below freezing, the pilot added a cold weather correction to the procedure turn altitudes before beginning the approach.
Example Sentence 2
Because of the extreme cold the crew added 600 feet to all procedure turn altitudes on the approach.