Definition
Published temperature thresholds, typically printed on instrument approach charts, that restrict the use of an approach procedure when the outside air temperature is outside the stated range. Above the high-temperature limit, the procedure may not be flown because aircraft true airspeed and turn radius increase to the point that obstacle protection on the procedure cannot be guaranteed. Below the low-temperature limit, barometric altimeters indicate higher than the aircraft's actual altitude, so a cold-temperature altitude correction must be applied to one or more published segment altitudes (or the procedure cannot be flown without that correction).
Plain English
Some approaches list a hottest and coldest temperature at which they are safe to fly. If it is hotter than the top limit, the approach is not allowed. If it is colder than the bottom limit, you must add a correction to the published altitudes because the altimeter will read higher than you actually are.
Context Anchor
Seen in instrument approach procedure notes, often near RNAV approaches with LNAV/VNAV minimums.
Why Pilots Care
Prevents altimeter errors that can lead to flying lower than indicated, ensuring safe obstacle clearance on approaches.
Grounding Statement
On a very cold or very hot day, a barometric system can make the airplane follow a vertical path that is not where the published approach designer intended it to be.
Intuition Check
Do not read these as comfort limits or general weather advice. In this FAA context, they are authorization limits for using specific instrument approach guidance or minimums.
Example Sentence 1
Before briefing the approach, the crew checked the chart and saw the procedure had a cold temperature limitation of -20 degrees C, so they applied the required altitude correction to the intermediate segment.
Example Sentence 2
Hot temperature limitations reduced our climb gradient, so we waited until cooler evening conditions before departure.