Operators with international routes are exposed to different standards in terms of:
• Altitude measurement, using different units (i.e., feet or meters);
• Altitude reference setting (i.e., baro setting), using different units (i.e., hectoPascal or inch-of-mercury);
• Altitude reference for departure and approach, using QNH or QFE; and,
• Environmental conditions (i.e., rapid atmospheric pressure changes and/or low OAT operation).
This Flight Operations Briefing Note provides a review and discussion of the following aspects, highlighting the lessons learned from incidents / accidents (particularly during approach-and-landing) :
• Barometric-altimeter reference (QNH or QFE);
• Use of different units for altitude measurement and reading (i.e., feet versus meters) and altimeter setting (i.e., In.Hg versus hPa);
• Setting of baro-altimeter bugs (as applicable) and radio-altimeter DH;
• Radio-altimeter callouts; and,
• Low-OAT operation.
Some contents are as follows:
QNH or QFE?, Altimeter-setting Units, Setting the Altimeter Reference, Use of Metric Altitudes, Changing the Altimeter Setting in Climb or Descent, Setting of Barometric-altimeter MDA / DA and Radio-altimeter DH, Radio-altimeter Callouts, Low OAT Operation, Operational and Human Factors Involved in Altimeter-setting Errors, Company Prevention Strategies and Personal Lines-of-Defense etc.