They tend to follow precise regulations based on what planes will use it, altitude, ambient temperature etc. https://www.faa.gov/regulations_policies/advisory_

They tend to follow precise regulations based on what planes will use it, altitude, ambient temperature etc. https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentid/22809 https://www.faa.gov/regulations_policies/advisory_circulars/...