Narrative:

The 1;000 ft and 500 ft callouts from barometric to radar altimeter (RA) present some challenges for situational awareness and stable approach criteria at some airports in the theater of operations of central and south america. Arriving under visual meteorological conditions to mroc (san jose; cr) the barometric marker at 1;000 ft equaled nearly 1;600 RA; and the corresponding 500 ft to almost 800 ft RA. We experienced a similar situation in mggt (guatemala city). First; when we go every 9 months to the simulator; we get to practice a non-electronic assisted visual approach for the exception of the fix page information to correlate altitude with distance. This allows for a stable approach to maintain an approximate 3 degree path. Secondly; the stable approach criteria is based on an aircraft configuration and energy state consistent with the first set of gates (1;000 ft then 500 ft) to preclude an undesired aircraft state. If we were to use the last 500 ft RA as a final gate; we would be much lower and closer to the ground than what the criteria requires and not be in violation of sops. Is this safe and logical? Then; what is the purpose to utilize an RA if is to provide inaccurate information? In seqm (quito) we would make more than one 1;000 ft callout when in fact we are 2;000 ft above the field. Again; for a stabilized approach; if I find myself at 1;000 ft and 6 miles out; I am going to level off; which is the wrong thing to do in this case. I can use similar arguments for many other airport.

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Original NASA ASRS Text

Title: Air Carrier Captain reported that Company SOPs of using Radar Altimeters for altitude callouts can provide inaccurate information when operating in Central American and South American airports.

Narrative: The 1;000 ft and 500 ft callouts from barometric to Radar Altimeter (RA) present some challenges for Situational Awareness and Stable Approach criteria at some airports in the theater of operations of Central and South America. Arriving under visual meteorological conditions to MROC (San Jose; CR) the barometric marker at 1;000 ft equaled nearly 1;600 RA; and the corresponding 500 ft to almost 800 ft RA. We experienced a similar situation in MGGT (Guatemala City). First; when we go every 9 months to the simulator; we get to practice a non-electronic assisted visual approach for the exception of the fix page information to correlate altitude with distance. This allows for a Stable Approach to maintain an approximate 3 degree path. Secondly; the Stable Approach criteria is based on an aircraft configuration and energy state consistent with the first set of gates (1;000 ft then 500 ft) to preclude an undesired aircraft state. If we were to use the last 500 ft RA as a final gate; we would be much lower and closer to the ground than what the criteria requires and not be in violation of SOPs. Is this safe and logical? Then; what is the purpose to utilize an RA if is to provide inaccurate information? In SEQM (Quito) we would make more than one 1;000 ft callout when in fact we are 2;000 ft above the field. Again; for a Stabilized Approach; if I find myself at 1;000 ft and 6 miles out; I am going to level off; which is the wrong thing to do in this case. I can use similar arguments for many other airport.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.