PEP Airbus RTOW charts
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Joined: Nov 2025
Aviation Qualifications: ATPL
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From: Europe
PEP Airbus RTOW charts
Hello everyone, this is my first ever PPRuNe post!
I’m looking for some insight into the accuracy of PEP-generated RTOW charts. Has anyone ever come across values that they considered questionable or potentially problematic? A colleague of mine is skeptical of these charts, claiming they sometimes produce “erroneous” results. One example he mentions is Istanbul LTFM, RWY 17R, at 132 t, attached.
At first glance the numbers may look counterintuitive, but I find it hard to believe that PEP would generate unsafe speeds. Less precise than FlySmart or other advanced tools, yes, but not unsafe.
Here’s my reasoning: up to 122 t, the aircraft is not performance-limited, regardless of wind. My assumption is that PEP therefore calculates a set of speeds using a fixed V1/VR ratio and applies them across all wind components.
At 132 t with 10 kt tailwind, a 4-4 limitation appears. Normally we’d expect V1 to decrease with a tailwind, but at 132 t in zero wind, the aircraft is not performance-limited, so the baseline V1 is relatively high.
In addition, the chart shows an allowable exceedance of +1.6 t, meaning the software expects you to calculate using 133.6 t, and therefore bumps the V-speeds slightly to reflect that.
This leads to two questions:
LGR
I’m looking for some insight into the accuracy of PEP-generated RTOW charts. Has anyone ever come across values that they considered questionable or potentially problematic? A colleague of mine is skeptical of these charts, claiming they sometimes produce “erroneous” results. One example he mentions is Istanbul LTFM, RWY 17R, at 132 t, attached.
At first glance the numbers may look counterintuitive, but I find it hard to believe that PEP would generate unsafe speeds. Less precise than FlySmart or other advanced tools, yes, but not unsafe.
Here’s my reasoning: up to 122 t, the aircraft is not performance-limited, regardless of wind. My assumption is that PEP therefore calculates a set of speeds using a fixed V1/VR ratio and applies them across all wind components.
At 132 t with 10 kt tailwind, a 4-4 limitation appears. Normally we’d expect V1 to decrease with a tailwind, but at 132 t in zero wind, the aircraft is not performance-limited, so the baseline V1 is relatively high.
In addition, the chart shows an allowable exceedance of +1.6 t, meaning the software expects you to calculate using 133.6 t, and therefore bumps the V-speeds slightly to reflect that.
This leads to two questions:
- What exactly is the difference between a “4-4” limitation code and a single “4”?
- Why do the V-speeds at 135 t decrease with increasing headwind, instead of the usual trend?
LGR
